hyperphagia in dementia: 1. the use of an objective and reliable method for measuring hyperphagia in...

Appetite, 1997, 28, 151–165

Hyperphagia in Dementia: 1. The use of an Objective and

Reliable Method for Measuring Hyperphagia in People with

Dementia

JANET M. KEENEUniversity of Oxford, Department of Psychiatry

TONY HOPEPractice Skills Project, John Radcliffe Hospital, Oxford

Up to one third of dementia sufferers eat an increased quantity of food, comparedwith their premorbid intake, at some stage during the dementia. A proportion ofthese eat extraordinarily large quantities if food intake is not restricted. In orderto investigate this phenomenon in detail, a reliable and standardized method ofquantifying the degree of hyperphagia is required. We report the development ofsuch a method. Twenty-six people with dementia, who were reported by theircarers to be hyperphagic, were compared with 14 matched non-hyperphagiccontrols with dementia and 14 matched normal elderly. Subjects were offered twostandardized meals, under specified conditions, ad libitum. One meal consisted ofa single food, the other of a mixture of foods. The total energy intake provideda reliable measure of the degree of hyperphagia. The single food meal was morereliable but the mixed meal was a more sensitive measure of the hyperphagia.

1997 Academic Press Limited

I

Although cognitive impairment is a diagnostic feature of dementia it is often thebehavioural problems which cause difficulties, both for the people themselves andtheir carers, and lead to their admission into institutional care (Haupt & Kurz,1993). Many of the behaviour changes involve “excess” behaviour. One of thesechanges is increased food intake (hyperphagia).

Hyperphagia can be clinically significant for a number of reasons. It can lead toa dramatic increase in weight which may create problems for carers, who are oftenelderly themselves, particularly in helping with intimate care. Increased weight mayalso lead to decreased mobility, as well as adding to health problems, for example

The authors gratefully acknowledge the help of John Blundell, Sandra Cooper, Christopher Fairburn,Kathy Gedling, Paul Griffiths, Robin Jacoby, the Oxford Project to Investigate Memory and Ageing aswell as the subjects and their carers who generously gave their time to help with our research. JanetKeene was a Medical Research Council research student and member of St Cross College, University ofOxford during the period when this research was carried out.

Address correspondence to: Janet M. Keene, University of Oxford, Department of Psychiatry,Warneford Hospital, Oxford OX3 7JX, U.K.

0195–6663/97/020151+15 $25.00/0/ap960061 1997 Academic Press Limited

152 J. M. KEENE AND T. HOPE

by leading to pressure sores. The restriction of food intake imposed by carers inresponse to the hyperphagia, can become a focus of aggressive behaviour. Finally,some hyperphagic subjects raid rubbish bins or attempt to eat noxious substances.A round-the-clock watch may need to be maintained to avoid the danger of poisoningand choking.

Previous studies have been either anecdotal or derived from interviews withcarers. Although many studies have noted profound changes in eating behaviourand the problems these can pose for carers, little is known about how commoneating problems are, or about their natural history. Morris, Hope and Fairburn(1989) and Hope and Allman (1991) found that 26% of a community sample ofsubjects with dementia had eaten more than premorbidly at some stage during theirillness. Burns, Jacoby and Levy (1990) reported that 10% of people with dementiawere binge-eating at any one time and Teri, Boroson, Kiyak and Yamagishi (1989)reported binging behaviour and altered food choice at some stage during the courseof the illness in 20% of Alzheimer’s disease patients.

Of a cohort of 85 subjects with dementia followed for up to five years, 28 (33%)ate more than premorbidly, at some stage in their illness (Keene & Hope, inpreparation). Of the 28 rated as eating more, 7 (8% of total cohort) were said to eatat least 150% of their premorbid intake. When sweet food was accessible, at least20 (24%) would continue to eat until it was finished and 9 (11%) were reported tocontinue eating any non-sweet food available until there was no more left.

There are reports of overeating in Pick’s disease (Hope & Allman, 1991),Huntington’s disease (Janati, 1985), dementia of the frontal lobe type (Neary,Snowden, Northen & Goulding, 1988), familial dementia of a non-specific nature(Kim, Collins, Parisi, Wright & Chu, 1981) and progressive subcortical gliosis, arare form of presenile dementia (Neumann & Cohn, 1967).

Hyperphagia can also be a feature of conditions not associated with dementia,for example bulimia nervosa, hypothalamic tumours (Celesia, Archer & Chung,1981; Bray, 1984), Kleine-Levin syndrome, Sanfilippo syndrome, fragile X syndrome,Parkinson’s disease and some cases of head injury (Morris & Hope, 1990). Theconditions which show the greatest parallels with hyperphagia in dementia arePrader-Willi syndrome (Zipf & Berntson, 1987) and Kluver-Bucy syndrome (Kluver& Bucy, 1938).

There is a wide spectrum in the degree of hyperphagia reported by carers. Somepeople eat such large quantities that major disruption of the physiological controlsof food intake is a highly probable cause. If this phenomenon is to be studied indetail then an objective and reliable way of quantifying the hyperphagia is needed.The method of giving test meals, either of a single food or of several foods, hasbeen used by many experimenters to investigate eating behaviour. A single food mealhas the advantage of simplicity, and the uniform texture allows the microstructure ofeating (e.g. changes in loading rate, chewing rate and intra-meal pauses) to bemonitored during the course of the meal (Walsh, Kissileff, Cassidy & Dantzic, 1989;LaChaussee, Kissileff, Walsh & Hadigan, 1992). The data on microstructure of eatingin dementia are reported elsewhere (Keene and Hope, 1996). Much work has beencarried out on normal young adults, for example investigating the satiating efficiencyof foods (Kissileff, Gruss, Thornton & Jordan, et al., 1984) or the effect of sweetnessand calories (Rogers & Blundell, 1989). Other studies have investigated eatingbehaviour in people with bulimia nervosa (Walsh et al., 1989; LaChaussee et al.,1992), obese men (Spiegel et al., 1987) and obese and underweight women (Speigel

153MEASURING HYPERPHAGIA IN DEMENTIA

& Stellar, 1990). Recently eating in normal elderly has been investigated (Rolls,Dimeo & Shide, 1995). The main aim of the studies reported here was to adapt sucha method in order to quantify hyperphagia in people with dementia.

M

Definition of Hyperphagia

Hyperphagia can be defined as the consumption of an abnormally large quantityof food. However, this leaves a number of issues open, in particular: what level ofintake should be regarded as hyperphagic and, under what conditions should theintake be measured? With regard to the first issue, it would be helpful to knowwhether hyperphagia in dementia is a distinct category of eating behaviour or anextreme of a continuum. In other words whether there is a range of food intakeamongst those with dementia, with marked hyperphagia at one end, normal intakeat the other end and no “point of rarity” in between. There are no data on thispoint. With regard to the second issue, a wide range of eating patterns are observed.For example, some people eat excessive quantities but of only one particular typeof food; some eat excess food only when it is easily accessible; some eat relativelysmall amounts but at frequent intervals whereas others eat large quantities at a time.This raises the question of whether the behaviour should be judged by a single mealor over a more sustained period of time?

We decided that the most promising approach to developing a standardizedobjective method for quantifying hyperphagia was to adapt methods previously usedin other clinical populations (e.g. obesity and bulimia nervosa). One or morestandardized single “meals” were given, with food available ad libitum, and theamount eaten (measured in kilojoules) was used as the measure of quantity. Becausethis study is the starting point for a series of experiments to investigate clear-cuthyperphagia we wished to include subjects who showed hyperphagia to a markeddegree. We also wished to derive a standardized measure which could be used toquantify the extraordinary overeating of severe hyperphagia.

We therefore chose to study three groups of subjects: Group A—People withdementia classified as “hyperphagic” on the basis of carer’s reports (“hyperphagicsubjects”). Group B—People with dementia classified as “not hyperphagic” on thebasis of carer’s reports (“non-hyperphagic demented controls”). Group C—Normalelderly control subjects (“normal elderly controls”).

Recruitment of subjectsSubjects for groups A and B were recruited through general practitioners,

community psychiatric nurses, ward nursing staff and hospital consultants. Subjectsfor group C were recruited mainly amongst the carers of people with dementiaalready known to the authors through other studies and the carers of subjectsincluded in this study.

The criteria for referral were as follows: Group A (hyperphagic subjects): patientswho had been diagnosed as suffering from dementia and for whom the main carerreported evidence of the person persistently overeating or wanting more food.Group B (non-hyperphagic demented controls): subjects diagnosed as suffering fromdementia but for whom there was no known evidence for hyperphagia.


Assessment of Subject Prior to Inclusion into the Study

Assessment of dementiaThe CAMDEX interview (Roth et al., 1986) was administered to potential

subjects for Groups A and B and their carers. Medical and psychiatric notes, whenavailable, were examined. On the basis of these sources of information the diagnosisof dementia was confirmed, the degree of dementia ascertained, using the Mini-Mental State Examination—MMSE (Folstein, Folstein & McHugh, 1975) which iscontained within CAMDEX, and the best diagnosis made for the cause of dementiausing the NINCDS-ADRDA criteria (McKhan, Drachman, Folstein, Katzman,Price & Stadlan, 1984).

Assessment of hyperphagia from carers’ reportsThe eating behaviour of all potential subjects with dementia was assessed through

semi-structured interview with the carers. This interview was a combination of theeating section of the Present Behavioural Examination (PBE—Hope & Fairburn,1992) which assesses current eating behaviour and the eating section of the PastBehavioural History Examination (PBHI) which was developed from the PBE andcovers behaviour since the onset of dementia.

Inclusion and Exclusion Criteria for the Three Groups

Group A—hyperphagic subjects

Inclusion criteria: (a) Diagnosis of dementia. (b) Probable cause of dementia:Alzheimer’s Disease, vascular dementia or both. (c) The carer reported that at leastone of the following obtained: (i) The subject was currently eating more than beforethe onset of dementia. (ii) The subject frequently showed signs of wanting morefood, either by searching or asking for more. (iii) The subject ate distinctly morethan normal when extra food was available.

Exclusion criteria: (a) A diagnosis of diabetes mellitus. (b) A premorbid history ofheavy alcohol intake, i.e. regularly exceeding 30 units a week for a period of morethan two years. (c) A serious head injury which might have contributed to thedementia. (d) The subject is incapable of feeding him/herself.

Group B—non-hyperphagic controls

Inclusion criteria: (a) and (b) as for experimental group. (c) The carer reported thatthe subject did not show signs of hyperphagia, i.e. the carer’s answers to PBEquestions confirmed that there were no signs of an excessively large appetite or ofan abnormally large food consumption. (d) The subject is capable of feeding him/herself. (e) The subject’s body mass index (BMI) is between 15 and 35 (so that thegroup matched group A).

Exclusion criteria: As for group A.

Group C—normal elderly controls

Inclusion criteria: (a) Normal appetite and eating habits. (b) Body mass index (BMI)between 15 and 35 (so that group matched group A).


Exclusion criteria: (a) Signs of dementia (MMSEΖ24). (b) Currently dieting to loseweight.

Matching of three groupsThe purpose of specifically recruiting hyperphagic subjects (group A) was to

ensure that we had a sufficient number of subjects who ate substantially more thannormal. In order to examine the relationship between reported hyperphagia andobserved food intake under standardized conditions, subjects in Group A wereindividually matched with subjects reported not to be hyperphagic (group B).

Subjects were matched for: age—within 3·5 years; sex; type of dementia—bothcontrol and subject had the same clinical diagnosis of either AD, vascular dementiaor probable mixed cause of AD and vascular dementia; and degree of dementia—MMSE score within 4 points.

Each normal elderly control was individually matched for age (within 3·5 years)and sex with a member of the hyperphagic group.

Standardized objective measurement of eatingAs a result of pilot work, two standardized situations were examined. Both

involved the subjects in a situation where a virtually unlimited supply of food wasavailable: a single food meal and a mixed ‘buffet’ meal consisting of many foodtypes.

Single food meal. Low-sugar digestive biscuits (approximate mass 9·1 g and energyvalue 175 kJ or 42 kcals, 6·1% protein, 23·1% fat, 69·1% carbohydrate) were chosenfor the single food meal. These were palatable but avoided the problem of intakebeing driven by sweetness. Small biscuits were used as people tend to finish any itemof food which they select, therefore with smaller food units the endpoint could bemore finely judged.

Ten biscuits were placed on a plain white plate with a similar empty plate directlyin front of the subject. A glass of water was placed on the table. When only two orthree biscuits were left, the plate was replenished, as unobtrusively as possible.Similarly, the glass of water was refilled when necessary.

Mixed meal. The purpose of the mixed meal was to assess total energy consumptionusing a more natural meal and giving a choice of familiar foods. The aim was togive a virtually unlimited supply of a variety of foods of different macronutrientcontent, satiating efficiency, taste, texture, appearance and energy value. The mixedmeal also allows food preferences and macronutrient choice to be examined. Thedata on food preferences and macronutrient choice are reported in the second paper.

Eight food types were given (Table 1). Apart from pear and cucumber, the foodswere cut into portions of similar energy value, approximately 175 kJ (42 kcals). Eachtype of food was placed separately on a similar plain plate so that it could be seenand picked up easily.

The plates were arranged in a semicircle, equidistant from the subject. Plateswere “topped up”, as unobtrusively as possible, during the course of the meal sothat a virtually unlimited quantity of any food could be eaten if desired.

Setting in which meals were given. To make conditions as normal as possible allmeals were given in the subject’s own home or in a familiar room if in an institution.


T 1Macronutrient content of foods for main study

Number of Approximate Macronutrient content (%)units total mass

Food item given initially given initially (g) Protein Fat Carbohydrate

Ham 4 108 20·5 5·6 0·7Cheese 8 136 29·0 14·0 0·2Bread and margarine 8 60 7·6 9·6 43·6Biscuit 8 73 5·7 23·9 69·0Cheese and butter

sandwich 8 80 7·5 33·3 23·3Sausage 8 107 13·4 31·2 10·7Pear 8 60 0·3 0·0 10·6Cucumber 8 60 0·6 0·1 1·8

Subjects were given their normal breakfast at the usual time and the conditionsin the room were kept constant on each occasion. To enable the mealtime behaviourto be analysed later all meals were videorecorded. During meals with people withdementia, it was essential for reasons of safety to keep constant watch. The observersat to one side, as far away as possible and was apparently ignored by the subject,as was the presence of the camera. For meals with the normal elderly, the observerwithdrew to another room in the house, unless otherwise requested, in order tominimize the observer effect, but returned at 5-minute intervals to check all was welland replenish food if necessary. Latency and ending of the meal were measured fromvideo recordings.

The following general rules were followed for all experimental meals: each testmeal was given with standardized instructions at the time when subjects usually hadtheir midday meal; subjects could not see other people eating as it might affect meal-size (Meyer, Pudel & Huszarik-Felgendreher, 1980) and be a distraction; before themeal, subjects were asked to regard this as their midday meal and to eat until theywere comfortably full. For subjects with dementia once food was put on the tableno further instructions were given. If the subject did not start to eat after twominutes, a standardized prompt was given. After a pause of two minutes followingthe last mouthful subjects were asked if they had finished. For reasons of safety themeal was stopped if the maximum intake of 12 000 kJ (approximately 3000 kcals)was reached or if subjects showed signs of being uncomfortably full. Otherwise themeal was considered to be finished five minutes after the last mouthful.

Relationship of timing between two meals. All subjects were given both the singlefood and mixed meal. The single food meal was given first and the mixed meal wasgiven at least a week later (range 1–10 weeks, median 1 week).

R S M

To establish the reliability of each type of meal, both types were repeated witha sample from each group. Ten people from the reported hyperphagic group and


10

047

Subject number

En

ergy

inta

ke (

MJ)

8

6

4

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45 21 29 58 50 53 65 41 51 68 31 19 42 67 24 49 59 66 52 07 36 55 02 37 09

Mean intake of normal elderly

F 1. Energy intake during biscuit test meal—all reported hyperphagics.

five from each of the demented non-hyperphagic control group and the normalelderly control group were given an identical repeat meal of each type, at least twoweeks after the first meal (range 2–21 weeks, median 4 weeks). The time intervalwas chosen in order to avoid the possibility that the memory of the previous mealwould affect intake. The position of foods in the mixed meal was altered on thesecond occasion to eliminate any position effect in the choice of food.

Reliability was measured by the degree of agreement in the amount consumedby individuals on the two separate occasions using the Pearson correlation coefficient.Student t-tests were used to examine whether there was any significant differencebetween the mean consumption for each subject group. This research was approvedby the local psychiatric ethics committee. Prior consent for videorecording wasobtained from all participants (where they were able to understand) and from allrelevant carers.

R

Subjects

Twenty-six subjects (7 were male) met the criteria for “reported hyperphagics”and they were given test meals (Figs 1 and 2).

As is seen from these figures, whilst many of the subjects ate very large quantitiesof food under these conditions, a number did not. Some possible reasons for thiswide range are taken up in the discussion. Because, for further studies, we wishedto compare a group of definitely hyperphagic subjects with both demented and


10

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Subject number

En

ergy

inta

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MJ)

8

6

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50 41 55 53 51 58 29 68 21 65 49 24 47 59 42 66 31 07 19 52 67 36 09 37

Mean intakeof normal elderly

F 2. Energy intake during mixed food test meal—all reported hyperphagics.

T 2Characteristics of the three groups

Observed hyper- Non-hyperphagic Normal elderlyphagic group demented controls controls

(5 men, 13 women) (5 men, 9 women) (5 men, 9 women)

Mean SD Range Mean SD Range Mean SD Range

Age (years) 75·3 8·0 54–91 77·6 6·3 67–89 76·2 8·4 55–87MMSEa 3·7 5·3 0–20 4·6 5·5 0–17 28·1 1·1 26–30Energy intakeBiscuit meal (MJ) 4·2 2·9 0·2–9·5 1·3 1·1 0·1–3·6 1·2 0·5 0·5–2·1Mixed meal (MJ) 5·5 2·7 1·9–9·8 2·0 1·2; 0·0–4·0 1·8 0·5 1·1–2·9

aMini-Mental State Examination score for degree of dementia.

non-demented controls, we needed to define a group of “observed hyperphagicsubjects”—i.e. a subset of “reported hyperphagic subjects” who also ate an abnormallylarge amount under these standardized conditions. We chose a rather stringentthreshold to define hyperphagia, viz the mean intake+ 3 standard errors of thenormal elderly group (Table 2). This gave a threshold of 2824 kJ for the biscuit mealand 3337 kJ for the mixed meal. Thus the “observed hyperphagic group” wasidentified as consisting of those individuals who were reported as hyperphagic andate more than the threshold during at least one of the first three test meals. Using


12

12

Biscuit meal 1 (MJ)

Mix

ed m

eal 1

(M

J)

10

10

8

6

4

2

2 4 6 80

F 3. Relationship between energy intake during the two types of test meal—biscuitmeal and mixed meal.ΦΦ , Hyperphagic group;+, Non-hyperphagic group; ∗, Normal elderlycontrols.

these criteria 18 of the original 26 reported hyperphagic subjects were included inthe observed hyperphagic group.

The mean intake of all three groups was much greater for the mixed meal t(44)=3·5, p= 0·001. There was a high correlation between intake at the single food mealand intake at the mixed meal (Pearson correlation 0·72, p<0·0005), this correlation wasgreatest in the hyperphagic group (0·56, p= 0·019). Figure 3 shows the relationship.

Effect of neuroleptic drugsThe only types of medication taken by these subjects which might have affectedappetite were neuroleptics. At the mixed meal 10 out of 25 (40%) of the reportedhyperphagics were taking medications in this category and 3 out 14 (21%) of thedemented control group were also taking such drugs. This was not a significantdifference. For the reported hyperphagic group, the mean food intake at the mixedmeal for those taking neuroleptics was 5771 kJ. However, in the non-hyperphagic


demented control group those on neuroleptics ate significantly more, 3298 kJ com-pared with 1629 kJ for those not on neuroleptics t(5)= 3·29, p= 0·025.

Other contributory factorsThere was no evidence that the hyperphagic group were more active than the

two control groups or that they were ex-dieters who had lost their former restraint.

Reliability

Biscuit meal 1 and 2For the biscuit meal, when all the three sub-groups, who were retested, were

combined, test-retest reliability was high (Pearson correlation 0·956, p<0·0005). Therewas good correlation between the intake at the two meals within the hyperphagicgroup (correlation 0·947; p<0·0005) and the normal group (correlation 0·963; p=0·008). Individuals showed high intra-subject reliability, each person eating a verysimilar amount at the two meals. The non-hyperphagic group was the most variable(correlation 0·611; p= 0·273), both in the amount eaten by different individuals andbetween how much each individual ate on the two occasions, i.e. the reliability forthis group was poor. The amount they ate seemed to depend on their mood, theirconcentration and their level of activity that day. The difference between the meanconsumption at the two test-meals for each of the individual groups was notsignificant.

Mixed meal 1 and 2Overall the test-retest reliability was high (for the total group—Pearson cor-

relation: 0·87; p<0·0005). For the hyperphagic demented group the correlation was:0·803; p= 0·005); for the non-hyperphagic demented group the correlation was:0·344; p= 0·571) and for the normal elderly the correlation was: 0·700; p= 0·188).The non-hyperphagic demented group (i.e. group B) was again the least reliable,both in the amount eaten by different individuals and in the amount eaten by thesame individual on different occasions. Individuals ate very similar amounts at thefirst and the second meal.

Comparison of Energy Intake at the Two Types of Meal

A comparison was made between the intake at the first digestive biscuit mealand at the first mixed meal. The results for all three groups (reported hyperphagics,non-hyperphagic and normal elderly) are shown as a scatter graph for the energyintake at the two meals (Fig. 3). The Pearson correlation for the hyperphagic groupwas 0·56, p= 0·019; for the non-hyperphagic demented group 0·301, p= 0·296 andfor the normal elderly 0·200, p= 0·493. The amount eaten at the mixed meal wasgenerally greater. The ratios of mean intake (measured in kJ) for the first biscuitmeal compared with the first mixed meal were: hyperphagic demented group (GroupA) 1 : 1·3; non-hyperphagic demented group (Group B) 1 : 1·6; normal elderlycontrols (Group C) 1 : 1·5.

D

In this paper, we report on the adaptation of methods, previously developed inother contexts, to investigate eating behaviour in people with dementia. We used


two standardized test meals to measure hyperphagia in dementia using directobservation as other methods are not suitable for this group.

Hyperphagia in dementia is a well-recognized phenomenon which is of clinicalimportance and theoretical interest. In order to be able to study this phenomenonin detail it is necessary to develop a standardized and objective method for definingand measuring the hyperphagia. This is particularly important for this group ofsubjects as it was not possible to assess hunger in someone with dementia, using theother methods such as visual analogue scales. Furthermore, systematically collecteddata from carers concerning subjects’ eating behaviour are unreliable, and can bemisleading because carers usually control the subjects’ access to food.

In both types of test meal subjects were provided with food ad libitum understandardized conditions. In the first setting, a single food was available (low-sugardigestive biscuits); in the second setting a variety of foods was available (e.g.sandwiches and fruit). Total energy intake was used as the measure of hyperphagia.The results show that these methods are reliable. The results also demonstrate thatsome people with dementia eat enormous amounts of food under these standardconditions.

The purpose of developing the standardized settings was for measuring anddefining hyperphagia in dementia.

Definition of hyperphagia

With regard to definition, a fundamental question is whether hyperphagia is acategory or whether it is a continuum. No reliable data concerning this point areavailable. The ideal study to answer this question would involve giving standardizedmeals, as developed in this paper, to a very large number of people with dementiaselected at random. In this paper we did not select subjects at random but studiedthree groups of subjects: those with dementia reported to be hyperphagic; those withdementia reported not to be hyperphagic and normal elderly controls. However,despite the fact that subjects were not selected at random the results do tend tosupport the view that there is a continuum of hyperphagia. As is shown in Fig. 1and 2, even amongst the group of reported hyperphagics there was a continuousspectrum of food intake without any obvious “point of rarity”.

If there is no point of rarity then it is to some extent arbitrary as to what shouldcount as a threshold of intake which defines hyperphagia. It is perhaps more accurateto talk of degree of hyperphagia rather than to use the term hyperphagia as acategory. However, for some purposes it is useful to be able to define a groupof hyperphagic subjects—for example for experiments aimed at comparing themechanisms of food intake in hyperphagic subjects with those in non-hyperphagicsubjects. We have suggested that the threshold of hyperphagia should be the meanplus three standard errors of the intake in the group of normal elderly.

In this sample only two more of the reported hyperphagic subjects would beincluded in the observed hyperphagic group by reducing the threshold from meanplus three standard errors to mean plus two standard errors. It might be asked whyit was decided to base the threshold on the normal elderly and not on subjects withdementia. The reason for this was that the epidemiological data suggest thathyperphagia is quite common in dementia. Therefore, if one were to define thethreshold based on the mean and standard error of people with dementia, the levelmight be unduly high. More profoundly, the point is that the concept hyperphagia


should be a concept based on normal functioning. Thus, it should be possiblelogically that all people with dementia are hyperphagic. This would be ruled out,even as a logical possibility, if the threshold for hyperphagia were based on a groupof people with dementia.

The main weakness in the criterion adopted is the small number of normal elderlyon which it was possible to base the mean and standard error. Ideally a larger sampleof normal elderly would be studied but the constraints of time made this impossiblewithin the present study.

The Effect of Being Observed

There is asymmetry in that an observer was present with the people with dementiabut not with the normal elderly. This was chosen to reduce observer interference asthis is more of a problem with normal people. The people with dementia appearedto be unaware of either the observer or the camera although it is also possible thatthe presence of a video camera may have acted as a deterrent to normal people.However, the results show that there was little difference between the intake of thenormal elderly who were aware of the conditions and the matched non-hyperphagiccontrols, who appeared to forget or be unaware of the presence of an observer anda camera. It is possible that people in Group A were not “hyperphagic” but unawareof being observed, whereas people with dementia who were in the “non-hyperphagic”group and the normal controls were inhibited when being observed. There are severalreasons for believing that this is an unlikely explanation. First, the non-hyperphagicdementia group were closely matched for cognitive ability and were therefore likelyto have a similar level of awareness to the hyperphagia group. Indeed, this was oneof the reasons for the inclusion of the non-hyperphagic dementia group. Second,the carers’ reports of subjects’ normal eating behaviour, under conditions where theywere unlikely to have been closely observed showed that the non-hyperphagic andnon-demented controls did not eat the enormous quantities eaten by the hyperphagicgroup. Third, some of the hyperphagic group ate so much food during the courseof one test meal that it seems unlikely this was simply the consequence of lack ofawareness of being observed. Fourth, analysis of the microstructure of eating duringthe course of the test meals (Keene & Hope; 1996) shows that the hyperphagic grouphad a significantly higher initial eating rate than the non-hyperphagic dementiacontrols. Indeed, some people ate so rapidly they needed to be restrained to preventthem from choking.

Comparison Between the Two Meals

All three groups of subjects and controls, in general, ate more during the mixedmeal and they ate for longer. Some people, in both groups with dementia, ate verylittle during the biscuit meal. Most of those who ate little were socially aware andappeared to be restraining their food intake, as if they thought it inappropriate toeat a large number of biscuits, at least when being observed. A probable reason forthe larger intake of the mixed meal is that people eat more when a variety of foodsis offered (Rolls, Rowe, Rolls, Kingston, Megson & Gunary, 1981; LaChaussee etal., 1992).


Reliability of the Standardized Meals

The results of both the biscuit meal and the mixed meal show first, that therewas a high degree of test-retest reliability: subjects consumed a similar amount whengiven the same meal on two separate occasions. This suggests that, if an objectivemeasure of hyperphagia can be made using standardized meals then a single mealis sufficient, at least for most purposes.

Reliability can also be looked at from the point-of-view of using both typesof standardized meal to classify subjects as hyperphagic or non-hyperphagic. Theclassification of all ten people in the normal elderly and non-hyperphagic controlgroups, who were retested, was reliable as all ten were classified as non-hyperphagic on both types of meal. Of the ten people in the hyperphagic groupwho were retested for each meal the same six people were classified as hyperphagicby each of the biscuit meals whereas all ten exceeded the threshold during oneor both of the mixed meals. Classification by the biscuit meal proved to be morereliable but the mixed meal was a more sensitive measure of hyperphagia asmore of the reported hyperphagic group overate when a variety of foods wereoffered.

The Relationships between Reported Hyperphagia and Observed Hyperphagia

The most striking result was that many reported hyperphagics did not comeup to the criteria for observed hyperphagics. This was not because the thresholdof intake for observed hyperphagics was set too high. Many of those who werereported to be hyperphagic ate merely normal or less than normal quantities offood in the standardized situations. There are several possible reasons why thosereported to be hyperphagic may not appear to be so under standardized conditions.(i) The standardized meal is treated as a mid-morning snack rather than a meal.This appeared true only of the biscuit meal. (ii) Some subjects may have foundthe single food (digestive biscuits) unattractive or unpalatable and this limitedthe amount they ate under experimental conditions. It was not possible to getsubjects with this degree of dementia to make palatability ratings. (iii) In thecase of one subject, the carer reported that the subject overate only on chocolates.This subject did not eat a large amount at the standardized meals. Whetherovereating only on chocolates should count as hyperphagia or not is unclear.(iv) A few subjects appeared to be sufficiently socially aware to be self-consciousof overeating when being observed. (v) Food intake prior to the standard mealmight have an effect. Although people were given their normal breakfast, oneperson was known to have helped herself to a substantial snack during the courseof the morning and shortly before the experimental meal. (vi) One subject wastoo restless to settle to eat. (vii) One subject lacked sufficient coordination tofeed himself efficiently.

All these are reasons why a genuinely hyperphagic subject might fail to eatenough to be classified as hyperphagic at a test meal. It is likely that there are alsosubjects who are reported to be hyperphagic but who are not genuinely hyperphagic,i.e. subjects who are correctly classified by the test meal as not hyperphagic. Somecarers may misreport behaviour and overestimate the amount eaten. In some casesthe subjects may once have been hyperphagic, causing the carer to restrict food, buthave ceased to be so.


Conclusion

The marked hyperphagia, seen in some subjects with dementia, can be reliablyquantified under standardized conditions. The standardized conditions which wereport in this paper provide a method for the further study of these subjects.

R

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Received 12 December 1995, revision 9 September 1996

hyperphagia in dementia: 1. the use of an objective and reliable method for measuring hyperphagia in...

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