comparison of the recovery patterns of language and cognitive functions in patients with...

Comparison of the recovery patterns of language

and cognitive functions in patients with

post-traumatic language processing deficits

and in patients with aphasia following a stroke

Mile Vukovic a,*, Jasmina Vuksanovic b, Irena Vukovic c

a Faculty of Special Education and Rehabilitation of the University of Belgrade, 11000 Belgrade, Serbiab Health Center - Zemun, 11000 Belgrade, Serbia

c Center for Multidisciplinary Studies, University of Belgrade, 11000 Belgrade, Serbia

Received 28 March 2006; received in revised form 3 April 2008; accepted 28 April 2008

Abstract

In this study we investigated the recovery patterns of language and cognitive functions in patients

with post-traumatic language processing deficits and in patients with aphasia following a stroke. The

correlation of specific language functions and cognitive functions was analyzed in the acute phase

and 6 months later.

Significant recovery of the tested functions was observed in both groups. However, in patients

with post-traumatic language processing deficits the degree of recovery of most language functions

and some cognitive functions was higher. A significantly greater correlation was revealed within

language and cognitive functions, as well as between language functions and other aspects of

cognition in patients with post-traumatic language processing deficits than in patients with aphasia

following a stroke.

Our results show that patients with post-traumatic language processing deficits have a different

recovery pattern and a different pattern of correlation between language and cognitive functions

compared to patients with aphasia following a stroke.

Learning outcomes: (1) Better understanding of the differences in recovery of language and

cognitive functions in patients who have suffered strokes and those who have experienced traumatic

brain injury. (2) Better understanding of the relationship between language and cognitive functions in

Available online at www.sciencedirect.com

Journal of Communication Disorders 41 (2008) 531–552

* Corresponding author.

E-mail address: [email protected] (M. Vukovic).

0021-9924/$ – see front matter # 2008 Elsevier Inc. All rights reserved.

doi:10.1016/j.jcomdis.2008.04.001

mailto:[email protected]

http://dx.doi.org/10.1016/j.jcomdis.2008.04.001

patients with post-traumatic language processing deficits and in patients with aphasia following a

stroke. (3) Better understanding of the factors influencing recovery.

# 2008 Elsevier Inc. All rights reserved.

1. Introduction

Considerable agreement exists about the pattern of recovery over time in aphasia.

Dramatic changes are observed during the first 2 or 3 weeks after a stroke (Kohlmeyer,

1976). Significant recovery is made during the first 2 months, but its progress will slow

down considerably after 6 months (Basso, Capitani, & Vignolo, 1979; Kertesz & McCabe,

1977; Vignolo, 1964). Etiology is frequently emphasized as the essential prognostic factor

of aphasia. Previous studies revealed differences in recovery from language processing

deficits caused by traumatic brain injury and from aphasia following a stroke. The

published studies indicate that language processing deficits after brain trauma have a better

prognosis than aphasia following a stroke (Basso, Capitani, & Moraschini, 1982; Kertesz &

McCabe, 1977; Luria, 1970; Marks, Taylor, & Rusk, 1957; Vukovic, 1998). For example,

Levin, Benton, & Grossman (1982) documented the full recovery of language functions in

some aphasic patients within the first 1–4 months post onset. Vukovic (1998) revealed that

patients with post-traumatic language processing deficits recovered faster and better than

patients with aphasia following a stroke, i.e. 40% of patients with post-traumatic language

disorders recovered completely during the first 6 months post onset. During the same

period, the full recovery of patients with aphasia following a stroke was recorded in 13.63%

of cases. The data provided by Laska, Hellblom, Murray, Kahan, & Von Arbin (2001) also

reveal a poorer recovery from aphasia following a stroke, i.e. only 24% of stroke patients

recovered completely, while 43% were still aphasic 18 months post onset.

Many studies revealed that, apart from the impairment of language abilities, aphasic

patients also have disorders in other aspects of cognition. Researchers are not unanimous,

however, on whether language impairment can be attributed to the impairment of other

cognitive functions or not. Caspari, Parkinson, LaPointe, & Katz (1998) point to a

correlation between working memory capacity, written language comprehension and

language function. The results of other researches also suggest that deficits in syntactic

comprehension in conduction aphasia can be attributed to a reduction in short-term verbal

memory rather than to a global deficit in language comprehension (Bartha & Benke, 2003;

Bartha, Marien, Poewe, & Benke, 2004; Caramazza, Basili, Koler, & Berndt, 1981).

Moreover, Bartha et al. (2004) state that patients in whom short-term verbal memory

function is preserved, perform syntactic comprehension tasks normally. This correlation

between short-term verbal memory and a deficit in word processing was also revealed by

Martin and Ayala (2004). Several earlier studies pointed to a correlation between language

and problem solving in aphasic patients (Archibald, Wepman, & Jones, 1967; Borod,

Carper, & Goodglass, 1982; Basso, De Renzi, Faglioni, Scotti, & Spinnler, 1973;

Hjelmquist, 1989). Kertesz and McCabe (1975) found that cognitive impairment was more

pronounced in patients with severe deficits in comprehension, such as patients with

Wernicke’s aphasia. Baldo et al. (2005) revealed a correlation between performance on

M. Vukovic et al. / Journal of Communication Disorders 41 (2008) 531–552532

language tests and problem-solving tests (Wisconsin Card Sorting Test and Raven’s

Coloured Progressive Matrices).

In contrast to these results, which imply that language and cognition are interrelated,

other researchers present opposite views. For example, Basso et al. (1973) and Hamsher

(1991) emphasize that cognitive deficits in aphasic patients are caused by a lesion in the

adjacent brain areas essential for cognition. These findings implicitly suggest that the

disorders of other aspects of cognition are not caused by a lesion in the brain areas essential

for language, and that the cognitive deficits observed in aphasic patients are not correlated

to language impairment. Similarly, Helm-Estabrooks (2002) did not discover a significant

correlation between linguistic and non-linguistic test scores, including visual attention,

memory, executive functions and visual-spatial skills.

In contrast to the opposite views with respect to a correlation between language and

cognitive disorders in aphasic patients following a stroke, language processing deficits in

patients with traumatic brain injury are often attributed to the impairment of cognition

(Hagan, 1984; Prigatano, Roueche, & Fordyce, 1986). The observation of language deficits

in the context of cognitive impairments resulted in the introduction of the term ‘‘cognitive-

communication disorder’’ (Hartley, 1995), which points out that language deficits in

patients with traumatic brain injury are secondary to, or at least occur in the context of,

cognitive impairments.

The above-mentioned data suggest differences in the outcome relative to etiology, i.e. the

recovery of language functions in patients with post-traumatic language processing deficits

and in patients with aphasia following a stroke. However, the recovery patterns of language

and cognitive functions in these two groups of patients are still not known with certainty.

The aims of this study were: (1) to analyze and compare the recovery patterns of

language and cognitive functions in post trauma patients with language processing deficits

and patients with aphasia following a stroke, (2) to investigate the relationship between

language functions (verbal fluency, auditory comprehension, naming and repetition) and

cognitive functions (short- and long-term verbal and visual memory and reasoning ability)

and, finally, (3) to find out whether there was a change in the correlation patterns of the

investigated functions during the course of recovery in order to investigate the recovery

patterns of language and cognitive functions in patients with post-traumatic language

processing deficits and in patients with aphasia following a stroke.

2. Methodology

2.1. Participants

A total of 71 patients, aged 18–61 participated in this study. The native language of all

subjects was Serbian and all subjects were right-handed. The subjects were divided into

two groups according to the etiology of their brain damage: the first group comprised 37

post trauma patients (PT) with language processing deficits and the second group

comprised 34 patients with aphasia following a stroke (SA).

The general characteristics of the tested groups are given in Table 1. The PT subjects are

significantly younger than the subjects with SA (t = �5.753; d.f. = 69, p < 0.001). The

M. Vukovic et al. / Journal of Communication Disorders 41 (2008) 531–552 533

groups also differ according to sex. In the group of PT patients there is a considerably

greater number of men than women as compared to the group of subjects with SA

(x2 = 6.005; d.f. = 1, p < 0.05). These data show that traumatic brain injuries are more

frequent in younger persons and that men are more frequent brain trauma victims than

women, which is also evidenced by the data from the relevant literature (Granacher, 2003).

On average, the level of education of patients with SA was considerably higher than that of

PT patients (t = 2.316; d.f. = 69; p < 0.05).

The type and localization of the brain lesions were obtained by computerized

tomography (CT) or magnetic resonance (MRI) scans at least 1 month post onset. All

patients with SA had a single left-hemisphere cerebrovascular accident (CVA), while 37

PT patients had a brain contusion or hematoma in the left hemisphere. Therefore, the

sample included only patients with unilateral left-hemisphere lesions and those with right-

hemisphere involvement were excluded. Prior to CVA or brain injury, the subjects had no

neurological or mental disorders.

Aphasia was assessed using the Boston Diagnostic Aphasia Examination (BDAE)

(Goodglass & Kaplan, 1983). The sample included patients with classic aphasic

syndromes: global aphasia, Broca’s aphasia, Wernicke’s aphasia, conduction aphasia,

transcortical mixed aphasia, transcortical motor aphasia, transcortical sensory aphasia and

anomic aphasia. Aphasia classification was based on the profile of language characteristics

obtained by analyzing the BDAE results. The diagnosis of mixed transcortical aphasia was

made on the basis of the nature and characteristics of language disorders in this aphasic

syndrome (Gonzalez Rothi, 1997). Although the type of aphasic syndrome was determined

mostly by assessing the modalities of spoken language (spontaneous speech,

comprehension, naming, repetition), this study included patients who, in addition to

the impairment of spoken language, had deficits in written language (reading and writing)

as well.

When determining the presence of language processing deficits in brain-injured

patients, in addition to their poor performance in the above-mentioned modalities of

spoken and written language, the presence of specific aphasic symptoms, such as

paraphasia, word-finding difficulties accompanied by breaks in speech and circumlocution,

syntactic deficits and production of meaningless words, was required for inclusion in the

sample. In other words, the sample only included patients with the symptoms of language


Table 1

General characteristics of the tested groups

PT (n = 37) SA (n = 34) t/x2-Test

Age (years) M (S.D.) 32.92 (10.91) 47.32 (10.12) t = 5.753**

Minimal age 17 18

Maximal age 61 61

Gender

Female 2 9 x2 = 6.005*

Male 35 25

Years of education M (S.D.) 10.49 (2.52) 11.85 (2.44) t = �2.316*

* p < 0.05.** p < 0.001.

impairment which are also observed in vascular aphasias. The sample did not include

patients whose profile of language impairments did not correspond to any classical aphasic

syndrome, i.e. unclassifiable patients were not included.

Patients with visual deficits and/or dementia, and subjects with severe apraxia were

excluded from the sample. Patients with severe right hemiparesis, who were unable to use

their left hand to write, and patients with constructional apraxia were also excluded from

the sample.1

2.2. Instruments and procedure

2.2.1. Language functions

Verbal fluency—there are several types of verbal fluency test, among which

phonological and semantic fluency tests are most frequently used. In this study the

subtest of naming animals (the Animal Naming Test) from the BDAE (Goodglass &

Kaplan, 1983), i.e. the semantic fluency test was used to assess naming ability, i.e.

generative naming. This is a verbal fluency test which can also be used in assessing

executive functions, while performance on this task is compromised not only in aphasia,

but also in other neurobehavioral syndromes (Spreen & Risser, 2003). Since the semantic

fluency test is highly correlated with visual confrontation naming and responsive naming

(Goodglass & Kaplan, 1983), we wished to assess naming ability under controlled

conditions. This is a very simple test and can easily be applied to aphasic patients. The

person administering the test instructs the patient to list as many animals as possible and

think about all animal species, and finally gives him/her support by producing the initial

word ‘‘dog’’. This instruction has a twofold significance: first, it ensures the preliminary

set, i.e. the naming framework and strategy, which can help the subject in switching from

one subcategory to the other; second, this instruction sets the clearly defined starting point

for timing, since many aphasic patients have difficulties in beginning a series of

associations, although their fluency level is acceptable when they begin to perform the task.

The subjects are given 90 s to list as many animals as possible. The score consists of the

number of different words named during the most productive consecutive 60-s period. The

score of the patients being unable to name any animal is 0.

Auditory comprehension was tested by the subtest commands from BDAE. In this

subtest, the capacity to process increasingly more concentrated auditory information was

tested with commands ranging from one to five significant informational units (Goodglass

& Kaplan, 1983). The patient is given commands one after the other, whereby each

command can be repeated only once, but in full. For each successfully executed command,

the patient receives a certain number of points, depending on the complexity of the verbal

command. The range of scores on this subtest is 0–15.

Repetition was measured by repeating the phrases and sentences from BDAE. We used

the set of ‘‘high-probability’’ sentences. The patients were asked to repeat the sentence

after the person administering the test. They received one point for each correctly repeated

sentence, so that the range of scores on this task is 0–8.


1 Institutional approval for human investigation was received prior to the subjects’ participation as stipulated by

the Helsinki Declaration. All subjects recruited for study participation were volunteers.

Confrontation naming was assessed using the Boston Naming Test (Kaplan, Goodglass,

& Weintraub, 1983). The Boston Naming Test has a shorter and a longer form. We used the

standard form of the test consisting of 60 drawings, which were ranked according to word-

usage frequency in everyday speech. The subjects are presented with drawings one after the

other and then asked to name each item. If the subject cannot retrieve the target word, or

recognize the given item, he/she is given semantic support. If he/she still cannot name the

presented item, he/she is given phonemic support. During the test, all answers to the visual

stimulus were recorded. For each correctly named item, the patient receives one point, so

that the range of scores on this test is 0–60. The total naming score is the sum of the

spontaneously given correct answers and the correct answers given after semantic support.

2.2.2. Cognitive functions

Reasoning ability was assessed by using the Raven Progressive Matrices Test—RPM

(Raven, 1960). This is a standardized test which can be administered to most individuals

with aphasia regardless of their language deficits. The test consists of a series of visual

pattern matching and analogy problems pictured in nonrepresentational designs. It requires

the subject to conceptualize spatial, design, and numerical relationships ranging from the

very obvious and concrete to the very complex and abstract. It consists of sixty items

grouped into five series. Each item contains a pattern problem with one part removed and

from four to eight pictured inserts of which one contains the correct pattern. The subject

points to the pattern piece he selects as correct or writes its number on an answer sheet.

Because the sample of subjects included aphasic patients, the person administering the test

recorded the answers of each patient on the appropriate form, rather than the subject

themselves. The total score for each subject was the number of the successfully solved

tasks. The patient can achieve 0–60 points on this test.

The first (Rey 1) and the sixth (Rey 6) part of the Auditory–Verbal Learning Test (Rey,

1964) assessed short- and long-term verbal memory. The Auditory–Verbal Learning Test

consists of a list of 15 words that is verbally presented to the subject five times and each time,

after the list of words is read, the subject is asked to repeat all the words that he/she remembers

(including those he/she repeated on the previous attempt), without paying attention to their

sequence. After the fifth repetition of the list of words, the subject is given some other task

and, after 20 min, he/she is asked again to repeat all thewords that he/she remembers from the

list which has previously been presented five times. The test was not analyzed in full; instead,

only the first and the sixth section assessing short- and long-term verbal memory were

analyzed. The patient’s total score is the number of successfully reproduced words.

Accordingly, the patient can receive 0–15 points after trying to repeat the list of words.

For the assessment of short- and long-term visual memory the Rey–Osterrieth Complex

Figure was used (Osterrieth, 1944). The test consists of two parts. In the first part, the

patient is asked to draw a horizontally placed figure on a blank piece of paper as precisely

as possible. At the same time, he/she is told to remember the figure. While drawing, the

patient uses different colours obtained from the person administering the test. The latter

monitors the drawing process and, each time the subject finishes a specified entity, gives

him/her a different colour, whereby he/she records the sequence of the colours used. In this

way, the strategy of drawing the figure is recorded. The testing period is not limited. After

the completion of this task, the model of the figure and the patient’s drawing are removed.


The other part of the test requires that the patient draw the figure from memory. The patient

is first asked to draw the complex figure from memory immediately after copying this

figure, which allows his/her short-term visual memory to be assessed. This procedure was

repeated 45 min after the copying of the figure so as to assess the long-term visual memory.

Scoring was done according to the procedure for the assessment of the results in this test

(Lezak, 1976).

Since the native language of all subjects was Serbian, all the tests were performed in

Serbian.

Each subject was individually tested. All tests were administered by the same

neuropsychologist twice: (1) within a median time of 20 days (range 10–30) post onset and

6 months later. Each patient was tested only after clinical assessment revealed that he/she

was able to perform the tests included in this study.

2.2.3. Statistical analyses

The data analysis included:

1. a comparison of the groups of subjects by variable and by group of variables;

2. a comparison of their scores on the first test and the retest;

3. assessment of the correlation between independent and dependent variables, as well as

the correlation between dependent variables in accordance with the set aims.

The analysis anticipated the use of parametric and nonparametric statistical procedures,

depending on the specific aims of the analysis and the nature of crossed variables (t-test, chi-

square, Mann–Whitney Z Test, Wilcoxon Z Test and Kendall’s correlation). The Mann–

Whitney Z Test was used to assess independent samples and the Wicoxon Z Test to examine

the results of the same groups in the acute phase and 6 months post onset. Differences in the

degree of recovery of language and cognitive functions in the tested groups were determined

by investigating the differences in the different scores using the t-test.

3. Results

3.1. Analysis of clinical data

An analysis of the data obtained by exploring the distribution of lesion sites in the tested

groups revealed no significant differences between PT patients and patients with SA

(x2 = 8.503, d.f. = 7, p > 0.05). However, the qualitative analysis shows that some

differences still exist, which can be of practical significance. Consequently, in PT patients a

significantly greater number of lesions are localized in the temporo-parietal regions than in

patients with SA. On the other hand, patients with SA had somewhat more frequent,

isolated lesions in the temporal and frontal regions than PT patients (Table 2).

The distribution of patients according to aphasia type in the acute phase revealed a

significant difference between the tested groups (x2 = 15.153; d.f. = 7; p < 0.05). In the

group of PT patients, fluent aphasias are dominant, while in the group of patients with SA

non-fluent aphasias are more frequent. Six months post onset, PT patients and patients with

SA also differed significantly with respect to the distribution of aphasic syndromes

(x2 = 35.663; d.f. = 7; p < 0.01). It is evident that in this period fluent aphasias are also


dominant in PT subjects, while in the group of subjects with SA, non-fluent aphasias are

more frequent. It should also be noted that a significant restitution of language functions

was observed in 12 PT patients, resulting in the full normalization of language functions,

meaning they no longer exhibited symptoms of aphasia or other symptoms of language

deficits. Such an effect, i.e. the full restitution of language functions was observed in only

two patients with SA. More detailed data on the types of aphasia in PT patients and in

patients with SA are shown in Table 3. It must be noted that Table 3 serves to approximate/

compare the language processing difficulties of patients in both groups with reference to

the standard aphasia types and that the language processing difficulties observed in the

post-traumatic group are classified according to the standard aphasia types for the purpose

of comparison in the paper.

3.2. Performance on the tested functions in the acute phase and 6 months post onset

An analysis of the results obtained by investigating language and cognitive functions

showed significant differences between PT patients and SA patients in the acute phase.


Table 2

Distribution of aphasia patients and post trauma patients with language processing deficits according to the site of

lesion

Site of lesion PT SA

Temporal 7 9

Temporo-parietal 13 6

Parietal 2 3

Fronto-temporal 4 3

Fronto-parietal 2 3

Fronto-temporo-parietal 3 4

Frontal 4 6

Diffuse contusion foci 2 0

Total 37 34

Table 3

Distribution of aphasia patients and post trauma patients with language processing deficits according to the

standard aphasia type in the acute phase and 6 months later

Aphasia type Acute phase Six months later

PT SA PT SA

Global aphasia 2 4 0 0

Broca’s aphasia 5 14 1 10

Wernicke’s aphasia 10 9 2 9

Conduction aphasia 3 2 2 1

Transcortical sensory aphasia 9 3 1 3

Transcortical motor aphasia 1 0 5 7

Mixed transcortical aphasia 2 2 4 0

Anomic aphasia 5 0 10 2

Recovery 0 0 12 2

Total 37 34 37 34

According to our data, PT patients displayed a significantly higher ability in sentence

repetition (Mann–Whitney Z Test = 3.609, p < 0.01) and higher verbal fluency (Mann–

Whitney Z Test = 2.609, p < 0.01) compared to patients with SA. Significant differences

were also revealed in favour of PT patients by assessing short-term (Mann–Whitney Z

Test = 2.660, p < 0.01) and long-term verbal memory (Mann–Whitney Z Test = 1.993,

p < 0.05). However, the investigation of short- and long-term visual memory and

reasoning ability did not reveal any significant differences between the tested groups of

patients. The results are shown in Tables 4 and 5.

An analysis of the results obtained through language function tests revealed 6 months later

that the performance of PT patients was significantly better when compared to patients with

SA on the assessment of the following linguistic functions: auditory comprehension (Mann–

Whitney Z Test = 2.519, p < 0.01) sentence repetition ((Mann–Whitney Z Test = 4.105,

p < 0.01) and verbal fluency (Mann–Whitney Z Test = 3.347, p < 0.01). Significant

differences were not only apparent in the naming test. As for cognitive functions, significant

differences were revealed in the reasoning ability (Mann–Whitney Z Test = 2.541, p < 0.01),

long-term verbal memory (Mann–Whitney Z Test = 2.086, p < 0.05) short-term visual

(Mann–Whitney Z Test = 3.020, p < 0.01) and long-term visual memory (Mann–Whitney Z

Test = 2.993, p < 0.01) in favour of PT patients.

The comparison of the results in the acute phase and 6 months later revealed a

significant recovery of language and cognitive functions in both groups of subjects, which

is shown in Tables 4 and 5. Our data reveal a significant recovery of language and cognitive

functions both in PT patients and in patients with SA during a 6-month interval. However,

by investigating the differences in recovery, i.e. differences in the scores obtained in the

acute phase and 6 months later, significant differences between the tested groups were

revealed. Namely, in the group of PT patients a significantly higher degree of recovery of

auditory understanding (t = 2.36, d.f. = 69, p < 0.05), naming (t = 2.15, d.f. = 69,

p < 0.05) and verbal fluency (t = 2.47, d.f. = 69, p < 0.05) was revealed when compared

to SA patients. As for cognitive functions, a significantly higher degree of recovery of

reasoning ability (t = 2.43, d.f. = 69, p < 0.05), short-term visual memory (t = 2.64,

d.f. = 69, p < 0.05) and long-term visual memory (t = 2.29, d.f. = 69, p < 0.05) was

revealed in PT patients than in patients with SA. The difference in the degree of recovery of

short-term (t = 1.21, d.f. = 69, p > 0.05) and long-term verbal memory (t = 0.26, d.f. = 69,

p > 0.05) is not statistically significant.

3.3. Correlation analysis

3.3.1. Correlation of language and cognitive functions

The correlation analysis of the investigated language functions in the group of PT

patients pointed to a significant inter-correlation of all investigated language functions,

both in the acute phase and 6 months later. It was also revealed that all investigated

cognitive functions were significantly correlated with auditory comprehension, verbal

fluency and naming, both in the acute phase and 6 months later. However, the repetition of

sentences was correlated with short-term verbal memory only in the acute phase and both

with short- and long-term verbal memory 6 months later. The results of the correlation

analysis of the investigated functions in PT patients are shown in Table 6.


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Table 4

The mean score on the assessment of language functions in the acute phase and 6 months later for PT patients and patients with SA

Acute phase Six months later Mann–Whitney Z Test/Wilcoxon Z Test

PT (n = 37) SA (n = 34) PT (n = 37) SA (n = 34) (1)(2) (3)(4) (1)(3) (2)(4)

Mean (S.D.) Mean (S.D.) Mean (S.D.) Mean (S.D.)

(1) (2) (3) (4)

Auditory comprehension 6.22 (5.10) 6.62 (4.81) 13.35 (2.76) 11.65 (3.87) 0.416 2.159* 5.091** 5.105**

Verbal fluency 4.24 (3.45) 2.18 (2.56) 12.95 (4.79) 8.91 (4.13) 2.609* 3.347** 5.310** 5.095**

Naming 14.46 (13.66) 14.88 (13.45) 39.14 (12.45) 34.03 (13.66) 0.39 1.342 5.304** 5.007**

Repetition of sentences 4.49 (3.18) 1.71 (2.26) 7.41 (1.76) 4.88 (2.66) 3.609** 4.105** 4.384** 4.808**

* p < 0.05; ** p < 0.01.

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Table 5

The mean score on the assessment of cognitive functions in the acute phase and 6 months later for PT patients and patients with SA

Acute phase Six months later Mann–Whitney Z Test/Wilcoxon Z Test

PT (n = 37) SA (n = 34) PT (n = 37) SA (n = 34) (1)(2) (3)(4) (1)(3) (2)(4)

Mean (S.D.) Mean (S.D.) Mean (S.D.) Mean (S.D.)

(1) (2) (3) (4)

Reasoning ability 29.54 (13.56) 25.38 (8.66) 34.73 (10.30) 29.24 (8.20) 1.660 2.541* 4.062** 4.871**

Short-term verbal memory 2.70 (1.97) 1.50 (1.62) 5.70 (2.63) 5.09 (2.39) 2.660* 0.901 5.105** 5.114**

Long-term verbal memory 4.11 (4.27) 2.18 (3.47) 10.08 (4.76) 7.91 (4.22) 1.993* 2.086* 5.238** 5.100**

Short-term visual memory 10.23 (8.28) 9.34 (6.82) 21.49 (8.05) 16.66 (5.63) 0.208 3.020* 5.231** 5.094**

Long-term visual memory 10.19 (8.89) 9.21 (7.05) 21.12 (7.53) 16.59 (5.86) 0.058 2.993* 5.088** 5.019**

* p < 0.05.** p < 0.01.

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Table 6

The results of the correlation analysis of the investigated functions in PT patients

Acute phase Six months later

Auditory comprehension Verbal

fluency

Naming Repetition

of sentences

Auditory comprehension Verbal

fluency

Naming Repetition

of sentences

Auditory comprehension – 0.622** 0.635** 0.362* – 0.448** 0.614** 0.441**

Verbal fluency – – 0.798** 0.566** – – 0.700** 0.485**

Naming – – – 0.605** – – – 0.584**

Reasoning ability 0.497** 0.351* 0.352* 0.094 0.513** 0.625** 0.590** 0.003

Short-term verbal memory 0.684** 0.726** 0.761** 0.499** 0.580** 0.611** 0.711** 0.423**

Long-term verbal memory 0.694** 0.770** 0.676** 0.320* 0.705** 0.789** 0.803** 0.461**

Short-term visual memory 0.517** 0.281* 0.344* 0.066 0.391* 0.283* 0.277* 0.048

Long-term visual memory 0.543** 0.300* 0.375* 0.057 0.367* 0.301* 0.284* 0.097

* p < 0.05.** p < 0.01.

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fC

om

mu

nica

tion

Diso

rders

41

(20

08

)5

31

–5

52

54

3

Table 7

The results of the correlation analysis of the investigated functions in SA patients


Auditory

comprehension

Verbal

fluency

Naming Repetition

of sentences

Auditory comprehension Verbal fluency Naming Repetition

of sentences

Auditory comprehension – 0.539** 0.722** 0.104 – 0.448** 0.614** 0.441**

Verbal fluency – – 0.628** 0.113 – – 0.700** 0.485**

Naming – – – 0.395* – – – 0.584**

Reasoning ability 0.160 0.092 0.150 0.040 0.188 0.148 0.121 0.357*

Short-term verbal memory 0.462** 0.628** 0.566** 0.628** 0.554** 0.651** 0.610** 0.692**

Long-term verbal memory 0.495** 0.593** 0.377* 0.165 0.543** 0.644** 0.473** 0.447**

Short-term visual memory 0.434** 0.143 0.362* 0.362* 0.372* 0.264* 0.276* 0.297*

Long-term visual memory 0.389* 0.118 0.347* 0.361* 0.417** 0.294* 0.262* 0.292*

* p < 0.05.** p < 0.01.

The correlation analysis of the investigated language functions in the group of patients

with SA shows that in the acute phase the correlation between the tested language functions

is not complete, auditory comprehension and verbal fluency do not correlate with repetition

of sentences. Six months later however, all the investigated language functions were

significantly correlated with each other. One can also observe a globally weaker correlation

between cognitive and language functions in the acute phase, while 6 months later all

investigated cognitive abilities, except reasoning ability, were significantly correlated with

the investigated language functions. The results of the correlation analysis of the

investigated language functions in patients with SA are shown in Table 7.

3.3.2. Correlation of the investigated cognitive functions

As for the inter-correlation of cognitive functions, it was observed that the correlation

matrix in PT patients differs from that in patients with SA.

The results of the analysis show that all investigated cognitive functions in PT patients

are significantly interrelated both in the acute phase and after a certain degree of recovery,

i.e. 6 months later. On the other hand, in patients with SA a weak correlation of cognitive

functions was revealed both in the acute phase and 6 months later, a higher degree of

correlation being observed after a period of 6 months.

The results of the correlation analysis of the investigated cognitive functions in PT

patients and in patients with SA are shown in Tables 8 and 9.

4. Discussion

The aims of this study were: (1) to analyze and compare the recovery patterns of

language and cognitive functions in post trauma patients with language processing deficits

and with patients who had aphasia following a stroke, (2) to investigate the relationship

between language functions (verbal fluency, auditory comprehension, naming and

repetition) and cognitive functions (short- and long-term verbal and visual memory and

reasoning ability) and finally, (3) to find out whether there was a change in the correlation

patterns of the investigated functions during the course of recovery in order to investigate


Table 8

Correlation analysis of cognitive functions in the acute phase and 6 months later in PT patients

PT patients


Reasoning

ability

Short-term

verbal

memory

Long-term

verbal

memory

Reasoning

ability

Short-term

verbal

memory

Long-term

verbal

memory

Reasoning ability – 0.456** 0.393* – 0.665** 0.667**

Short-term verbal memory – – 0.804** – – 0.797**

Short-term visual memory 0.506** 0.376* 0.405** 0.358* 0.373* 0.424**

Long-term visual memory 0.465** 0.357* 0.416** 0.309* 0.333* 0.403**

* p < 0.05.** p < 0.01.

the recovery patterns of language and cognitive functions in patients with post-traumatic

language processing deficits and in patients with aphasia following a stroke.

Analysis of the data obtained by tests in the acute phase revealed that patients with post-

traumatic language processing deficits have better preserved repetition abilities (repetitive

speech) and better performance on the verbal fluency test, i.e. better naming ability

according to the semantic category, than patients with SA. Therefore, on the basis of our

results, it can be stated that performance on the semantic verbal fluency test and sentence

repetition test can have differential diagnostic significance in the assessment of language

impairment in patients with traumatic brain injury and in patients with aphasia following a

stroke. Better repetition ability in patients with post-traumatic language processing deficits

is the result of a higher frequency of types of aphasia with preserved repetitive speech, i.e.

transcortical sensory aphasia and anomic aphasia in this population relative to patients with

aphasia following a stoke. The frequency of anomic aphasia in patients with traumatic

brain injury is also described by other authors (Levin, Grossman, & Kelly, 1976; Thomsen,

1975). Heilman, Safran, & Geschwind (1971) also reported that brain-injured patients

often had anomic as well as Wernicke’s aphasia. Apart from these types of aphasic

syndromes, some authors point to the frequency of transcortical sensory aphasia in the

population of patients with traumatic brain injury (Vukovic, 1998). Accordingly, the

previous studies point to a higher frequency of fluent aphasias relative to non-fluent aphasic

syndromes in brain-injured patients (Heilman et al., 1971; Levin et al., 1976; Sarno, 1980,

1991; Sarno, Buonaguro, & Levita, 1986; Vukovic, 1998). Naming deficits are

characteristic of both fluent and non-fluent aphasia, but the better performance on the

semantic verbal fluency test in patients with post-traumatic language processing deficits

indicates that fluent aphasia, as category, tends to be less severe than non-fluent aphasia.

Since language deficits in patients with traumatic brain injury are often related to the

impairment of cognitive functions (Hagan, 1982, 1984; Prigatano et al., 1986), and the

relevant studies show that semantic fluency relies to a lesser degree on verbal ability than

on strategic search processes (Bryan & Luszcz, 2000), it is possible that better performance

on the semantic verbal fluency test in patients with post-traumatic language processing

deficits in the acute phase reflects better preserved language and cognitive functions in this

group of patients relative to patients with aphasia following a stroke.


Table 9

Correlation analysis of cognitive functions in the acute phase and 6 months post onset in patients with SA

SA patients


Reasoning

ability

Short-term

verbal

memory

Long-term

verbal

memory

Reasoning

ability

Short-term

verbal

memory

Long-term

verbal

memory

Reasoning ability – 0.018 0.012 – 0.101 0.141

Short-term verbal memory – – 0.783** – – 0.688**

Short-term visual memory 0.144 0.136 0.264* 0.351* 0.277* 0.301*

Long-term visual memory 0.257** 0.109 0.153 0.348* 0.305* 0.321*

* p < 0.05.** p < 0.01.

In view of the fact that the verbal fluency test is used, apart from the assessment of

aphasia (Spreen & Risser, 2003), for the assessment of executive functions, which are

attributed to the function of the frontal regions (Sohlberg & Mateer, 2001), this test is

regarded as especially sensitive in patients with anterior pathology (Baldo, Shimamura,

Delis, Kramer, & Kapla, 2001). Although our data did not reveal statistically significant

differences in the lesion sites between patients with post-traumatic language processing

deficits and patients with aphasia following a stroke, it can be said that the lesion sites in

the group of patients with aphasia following a stroke were somewhat more frequently

in frontal regions compared to patients with post-traumatic language processing deficits.

In view of this fact, the better performance on the semantic verbal fluency task in patients

with post-traumatic language processing deficits may also be partly explained by

differences in the anatomic and physiological basis of post-traumatic language processing

deficits and vascular aphasias. To confirm this, however, additional research will be

necessary.

The results of the tests performed 6 months later revealed a significant restitution of the

investigated language and cognitive functions in both groups of patients. When comparing

their performance, it was observed that patients with post-traumatic language processing

deficits demonstrated significantly higher abilities in semantic verbal fluency and

repetition, as in the acute phase, but also in auditory language comprehension abilities,

which was not apparent in the first test. By testing differences in the degree of recovery

between the two groups of patients, a significantly higher restitution of comprehension,

naming and verbal fluency was revealed in patients with post-traumatic language

processing deficits compared to the group of patients with aphasia following a stroke. A

more significant restitution in patients with post-traumatic language processing deficits

was also observed in respect of reasoning ability and short-term visual memory. Therefore,

it could be said that patients with post-traumatic language processing deficits recover better

than patients with aphasia following a stroke, which would support the earlier findings that

etiology is a significant prognostic factor of aphasia (Basso et al., 1982; Butfield &

Zangwill, 1946; Kertesz & McCabe, 1977; Luria, 1970; Marks et al., 1957; Vukovic, 1998;

Wepman, 1951). However, better recovery can also be partly explained by the severity of

the language disorder; the impairment of verbal fluency and sentence repetition in patients

with post-traumatic language processing deficits was milder in the acute phase relative to

patients with aphasia following a stroke. Furthermore, there were more cases of milder

forms of aphasia, such as anomic aphasia, and fewer cases of global aphasia in this group,

which also suggests that the impairment of language functions in patients with post-

traumatic language processing deficits was milder. Consequently, our findings support

some earlier studies which indicated that the initial severity of aphasia could be of

prognostic value (Basso et al., 1979; Kertesz & McCabe, 1977). It must be noted, however,

that the patients with traumatic brain injury included in this study were significantly

younger relative to stroke patients which also poses the question of the effect of age on

recovery. Although aphasiologists generally consider age as an important variable,

evaluations of the effects of age on recovery are not consistent. While some authors

consider age as an important factor, emphasizing that fewer older patients recover than

younger ones (Marshall, Tompkins, & Philips, 1982), others reported that age had no effect

on recovery (Sarno, 1980). Similarly more recent investigations have not demonstrated that


personal factors, including age, sex, handedness and educational level, have an important

role in recovery (Basso, 2003; Cappa, 1998).

It is evident that in the group of patients with post-traumatic language processing

deficits the observed recovery patterns of most language and some cognitive functions

were better relative to patients with aphasia following a stroke. These differences in

recovery cannot be explained simply by the fact that they were better at the very beginning.

In the acute phase, some of the language functions and most of the cognitive functions of

patients with post-traumatic language processing deficits were not significantly better than

those of patients with aphasia following a stroke, while 6 months later they achieved

significantly better results. We should note in particular the significantly better recovery in

reasoning ability, together with auditory comprehension, and naming, because patients

with post-traumatic language processing deficits had somewhat lower scores on these

language functions relative to patients with aphasia following a stroke. Such a finding

could be in favour of the cognitive-communication disorder profile, that is, the view that a

correlation exists between cognitive and language functions. During the 1980s and 1990s,

there was an increased interest in investigating the relationship between communication

abilities and cognitive disorders. Some authors, who confined themselves to the

investigation of patients with traumatic brain injury, related the observed language deficits

to cognitive impairments. So, for example, Hagan (1984) points out that common cognitive

impairments after traumatic brain injury affecting attention, memory and associative

abilities result in a reduction in the organization of one’s thoughts and concomitant

disorganization of language processes, including irrelevant utterances, word-finding

problems, and impaired sequencing of language output, as well as the impaired

comprehension capacity of complex auditory or written information. Prigatano et al.

(1986) also report some language deficits, such as poor word selection in patients with

traumatic brain injury, for example, to the impairment of cognitive processes.

Correlation analysis provides additional data. In the group of patients with post-

traumatic language processing deficits all language functions are significantly correlated,

most of them to a high degree, both in the acute phase and 6 months later. In addition, in this

group of patients, language functions are significantly moderately or highly correlated with

all tested cognitive functions except for repetition (which is not correlated with reasoning

and visual memory). On the other hand, patients with aphasia following a stroke display a

different correlation pattern of the tested functions. In the acute phase not all language

functions are inter-correlated and language functions are not tightly correlated with the

tested cognitive functions. These differences in a correlation between language and

cognitive functions also support the thesis that patients with traumatic brain injury have the

cognitive-communication disorder profile.

The existence of a correlation between specific language functions (auditory

comprehension, naming and verbal fluency) and reasoning ability in the acute phase

and 6 months later in patients with post-traumatic language processing deficits, on one side,

and the absence of a correlation between the investigated language functions and reasoning

in the group of patients with aphasia following a stroke, on the other, deserve special

comment. This finding is all the more significant if one bears in mind that this discrepancy

in the correlation between language and cognitive functions in our study is related to the

etiological factor of brain damage, i.e. the etiology of language disorders. Namely, the


revealed correlation between the mentioned language functions and reasoning in the group

of patients with post-traumatic language processing deficits supports the findings of some

authors that language impairment is manifested as the impairment of cognition (Baldo

et al., 2005). On the other hand, the absence of correlation between the investigated

language functions and reasoning ability in the group of patients with aphasia following a

stroke suggests the opposite conclusion. From that aspect, our findings in patients

following a stroke are consistent with the findings of Basso et al. (1973) and Basso,

Capitani, Luzzatti, & Spinnler (1981), who also failed to detect a correlation between the

performance on the RPM test and language scores. Therefore, it can be stated that

cognition in patients with aphasia following a stroke is impaired and that language

disorders are not so strongly related to cognitive deficits as in patients with post-traumatic

language processing deficits. The finding that aphasic patients performed more poorly on

the RPM test compared to the non-aphasic group of subjects, suggests that such

performance could be attributed to a lesion in the adjoining brain areas essential for

cognition (Basso et al., 1981, 1973).

It is important to note that this study revealed the inter-correlation of the investigated

language functions and short-term verbal memory in both groups of patients, in the acute

phase and 6 months later. In the acute phase, patients with post-traumatic language

processing deficits had significantly better short- and long-term verbal memory compared

to patients with aphasia following a stroke. Six months later, however, there was no

difference in the performance on the test of short-term verbal memory between these two

groups of patients. These findings suggest that the improvement of language functions in

stroke patients can partly be explained by the inter-correlation of short-term verbal

memory and language functions, on one side, and a significant restitution of short-term

verbal memory, on the other. It is possible that in a certain phase of recovery, while

performing some language tasks, stroke patients rely to a greater extent on the system of

short-term verbal memory, which leads to the lessening of the aphasic syndrome and, in

some cases, to the normalization of language functions.

There is no doubt that the inter-correlation of the investigated language functions and

short-term verbal memory in aphasic patients, both in the acute phase and 6 months later, as

well as the significant recovery of language functions and short-term verbal memory

support the thesis that the system of short-term verbal memory and the linguistic system

function together on the tasks requiring the processing and temporary retention of

linguistic representations, which is consistent with the results of earlier studies (Berndt &

Mitchum, 1990; Martin & Ayala, 2004; Martin & Saffran, 1997). Such a correlation was

also revealed in healthy persons (Hulme, Maughan, & Brown, 1991). The fact that on the

second test, i.e. 6 months later, patients with post-traumatic language processing deficits

performed significantly better on most memory ability tests relative to patients with

aphasia following a stroke, shows that memory may have a specific role in the restitution of

language functions in aphasic patients. Significant differences in the degree of recovery of

all the investigated language functions, with the exception of sentence repetition, and in the

recovery of short-term visual memory in patients with post-traumatic language processing

deficits, also point to the role of memory in recovery from aphasia. Although it is difficult

to determine precisely whether in the case of aphasia the recovery of language functions

precedes that of verbal and visual memory or not, our results and the work of other authors


(see: Martin, Saffran, & Dell, 1996) reveal simultaneous language and memory

improvement during the course of recovery from aphasia. A significantly better

performance on long-term verbal memory tests, as well as short- and long-term visual

memory tests, 6 months later, on one side, and a higher degree of recovery of specific

aspects of memory together with a better recovery of language functions in patients with

post-traumatic language processing deficits, on the other, show that the status of memory in

aphasic patients can represent a significant prognostic factor of aphasia. In addition, a

significant correlation between verbal and visual memory in patients with post-traumatic

language processing deficits, on both tests, and the absence of a significant inter-correlation

of these two memory modalities in post-stroke aphasic patients in the acute phase, on one

side, and their correlation after a certain degree of recovery, on the other, also support the

assumption that the status of memory is correlated with recovery from aphasia.

Appendix A. Continuing education

1. Which language functions improved significantly better in patients with post-traumatic

language processing deficits compared to the patients with aphasia following a stroke?

a. Auditory comprehension and repetition.

b. Repetition and naming.

c. Repetition and verbal fluency.

d. Naming, auditory comprehension and verbal fluency.

e. None of the above.

2. Which cognitive functions improved significantly better in patients with post-traumatic

language processing deficits compared to the patients with aphasia following a stroke?

a. Reasoning ability and short-term verbal memory.

b. Short-term visual and long-term verbal memory.

c. Reasoning ability, short-term visual and long-term visual memory.

d. None of the above.

3. In the present study what was the pattern of correlation between language and cognitive

functions in patients with post-traumatic language processing deficits?

a. All language functions were significantly correlated with examined cognitive

functions.

b. Repetition only was significantly correlated to reasoning.

c. Auditory comprehension was only correlated with memory.

d. No significant correlation was established between the tested language and

cognitive.

4. What was the pattern of correlation between language and cognitive functions in

patients with aphasia following stroke?

a. All examined language functions were significantly correlated with cognitive

functions.

b. There is a weak correlation between some cognitive and language functions.

c. Only reasoning is significantly correlated with language functions.

d. No significant correlation was established between the tested language and cognitive

functions.


5. What cognitive domain is connected with the process of recovery of language functions

in post trauma patients and stroke patients?

a. Reasoning ability.

b. Visual Memory.

c. Verbal and visual memory.

d. None of the above.

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