screening for alzheimer’s disease general principles

Screening for Alzheimer’s DiseaseGeneral Principles

J.W. Ashford,

University of Kentucky

Veterans Affairs Medical Center

Lexington

AAGP – 3/3/03

Early Recognition of AD: Consensus Statement

(AAGP, AGS, Alzheimer’s Association)

AD continues to be missed as diagnosis

AD is unrecognized and under-reportedpatients do not realized families tend to compensate

Effective treatment and management techniques are available

Small et al., JAMA, 1997

Why Diagnose AD Early?Safety (driving, compliance, cooking, etc.)Family stress and misunderstanding (blame, denial) Early education of caregivers of how to handle patient (choices, getting started)Advance planning while patient is competent (will, proxy, power of attorney, advance directives)Patient’s and Family’s right to knowSpecific treatments now available May slow underlying disease process May delay nursing home placement longer if started

earlier

Importance of screening for Alzheimer’s disease

Early treatments may: Slow the course of the disease Delay nursing home placement Decrease the cost of the disease

Very early treatments may prevent dementia

What is the cost of testing versus the cost of not testing?

At what age is testing cost-effective?

U.S. Census 2000 by age

0

250,000

500,000

750,000

1,000,000

1,250,000

1,500,000

1,750,000

2,000,000

2,250,000

2,500,000

0 10 20 30 40 50 60 70 80 90 100

Age

# p

eo

ple

Males,138,053,563Females,143,368,343

Total = 281,421,906>60 = 45,809,291>65 = 35,003,844>85 = 4,251,678>100= 62,545

U.S. mortality by age - 1999

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

0 10 20 30 40 50 60 70 80 90 100

Age

Nu

mb

er

of

pe

op

le

Males, 1,175,460

Females, 1,215,939

U.S. mortality rate by age1999 CDC / 2000 census

0.0001

0.0010

0.0100

0.1000

1.0000

0 10 20 30 40 50 60 70 80 90 100

Age

prob

abi

lity

MalesFemalesdementia incidence

U.S. mortality rate by age1999 CDC / 2000 census

y = 9E-05e 0. 0848x

R 2 = 0.9974y = 3E-05e 0. 0926x

R 2 = 0.9973

0.0001

0.0010

0.0100

0.1000

1.0000

30 40 50 60 70 80 90 100

Age

pro

bability

Males, Td = 8.2 yrs

Females, Td = 7.5 yrs

Expon. (Males, Td =8.2 yrs)Expon. (Females, Td =7.5 yrs)

U.S. Dementia Incidence (4 million / 8yr)

02000400060008000

10000120001400016000

50 60 70 80 90 100

Age

# /

yr

male=170,603

female=329,115

Dementia incidence by individual

00.0020.0040.0060.0080.01

0.0120.0140.016

50 60 70 80 90 100

Age

Pro

po

rtio

na

l ris

k /

yr

male=34%

female=66%

Age Specific Dementia Rate

0.0001

0.001

0.01

0.1

1

50 60 70 80 90 100

Age (years)

Pro

ba

bili

ty /

yr

Factors Influencing Variation in Age of Onset

Genetics (especially APOE), family historyNeurological factors Stroke Brain injury

Medical factors Vascular disease Medications: NSAIDS, statins, female HRT

EducationGenderAgeism (more concern for younger individuals)

Age-Associated Memory Impairment(loss of memory without loss of social function)

vs

Mild Cognitive Impairment / Early Alzheimer

Memory declines with age At what point is memory abnormal?

Heisenbergian uncertainty – the earlier problem is, the less clearly defined it is.

How does age affect consideration of abnormality? Memory problems are more tolerated in older individuals

Older individuals remember more complex items and relationships

Older individuals are slower to respond

Estimate MMSE as a function of time

0

5

10

15

20

25

30

-10 -8 -6 -4 -2 0 2 4 6 8 10

Estimated years into illness

MM

SE

scor

e

AAMI / MCI DEMENTIA

ALZHEIMER’S DISEASE

Ashford et al., 1995

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Age

Perc

enta

ge AD

MCI

Non-Affected

Yesavage et al., 2002

BLT/Ashford Memory Test(to detect AD onset)

New test to screen patients for Alzheimer’s disease using the World-Wide Web – based testing

Test only takes 1-minute

Test can be repeated often (quarterly)

Any change over time can be detected

Test is at: www.ibaglobal.com/BLT

For info, see: www.medafile.com