Do Instrumental Activities of Daily Living Predict Dementia at 1- and 2- Year Follow-Up? Findings from the Development of Screening Guidelines

and Diagnostic Criteria for Predementia Alzheimer’s Disease Study

Sietske A. M. Sikkes, PhD, Pieter Jelle Visser, MD, PhD, Dirk L. Knol, PhD, et al.

JAGS; December 2011, vol 59, No. 12

Payal PatelMercer University, College of Pharmacy and Health Sciences

RTR Medical Group1/31/2012

Background & study purpose

• Dementia is the most common disease in later life• Diagnosis is based on decline in scales that assess

disabilities in activities of daily living (ADLs)• ADL refers to basic activity of daily living (BADL)

and instrumental activities of daily living (IADL)• Complex activities are more sensitive to cognitive

decline in early stages of dementia • IADL assessment can play an important role in

screening/diagnosing dementia

Background & study purpose• Several studies have investigated the use of

IADL scales in diagnosing dementia• Previous studies showed variable results from

no correlation to strong association• Difficult to compare because the selection of

items and participants vary• This study investigates whether interference in

IADLs can predict dementia at 1 and 2 year follow-up in a memory clinic setting

Study Design and Population• Prospective cohort study

• Participants selected from DESCRIPA study which was done by the European Alzheimer’s Disease Consortium

• Participants recruited from 20 memory clinics across Europe between January 2003 and June 2005

Study Design and Population

• Inclusion Criteria: Age 55 and older with a new referral due to cognitive complaints

• Exclusion Criteria: patients with cognitive impairment due to somatic, psychiatric or neurological disorder

Outcome Measures

• Instrumental Activities of Daily Living• Different IADL scales were used between the

study centers: 16 centers used an IADL scale• 9 used Lawton IADL scale• 3 used Blessed Dementia scale and Bayer ADL

scale• 1 used Alzheimer’s Disease Cooperative study ADL

scale• 1 used Bristol ADL scale

Primary outcome

• All questionnaires completed by informant of the participant

• Items related to IADLs were chosen from the questionnaires

• Item content that overlapped between the different tests was selected to pool IADLs

• Responses were dichotomized to ‘no problems’ or ‘slight to severe problems’

Outcome Measures

• Cognitive Examination– MMSE– Memory tests –• Varied between the centers • Primarily Rey Auditory Verbal Learning Test

– Depression• Different scales between the centers• Scores dichotomized for clinically significant depressive

symptoms in each of the scales

Statistical method

• Statistical analysis were performed using M-Plus version 6.1 and SPSS

• Differences between participants with and without dementia were analyzed with independent t tests or chi square

Statistical methods

• Item response theory was used to model the dimensional structure of IADLs

• The relationship between IADL and the diagnosis of dementia, depression, and memory were modeled using SEM

• P<0.05 was considered statistically significant

Results• sample size = 616 participants • 1st year = 531 • 2nd year = 481

• Nine items were chosen: shopping, telephone use, housekeeping, transport, finances, medication, food/drink preparation, laundry, handling money

• 13 % developed dementia in 1 year with most common cause being Alzheimer’s

• 20.8 % patients had developed dementia in 2 years

Results

• Participants with at least one IADL problem had a higher rate of having dementia after 1 year (15.9%) compared to participants without IADL problems (P = 0.04)

• Participants with IADL disabilities at baseline also had a higher rate of dementia at 2 years (24.4%) compared to participants who did not have IADL problems (P = 0.04)

Results

• Participants who developed dementia were mostly older (p = 0.02) with lower MMSE scores ( p < 0.001) and greater memory impairments (p < = 0.001) at baseline

• Depression was not found to be a risk factor for developing dementia

ResultsCharacteristic N = 531 Dementia (n =

69) at 1 yearNo Dementia (n = 462) at 1 year

P value

Age, mean +/- SD 69.6 +/- 7.5 71.5 +/- 7.8 69.3 +/- 7.4 0.02Female, n (%) 315 (59.3) 46 (66.7) 269 (58.2) 0.18Education, n Primary 201 27 174 0.95 Secondary 201 25 176 >Secondary 129 17 112MMSE score, median (range)

28 (26-29) 27 (25-28) 28 (27-29) < 0.001

MemoryZ –score, mean +/- SD

-1.08 +/- 1.34 -2.04 +/- 1.08 -0.94 +/- 1.32 <0.001

Depressed, n (%) 50 (10.0) 3 (4.4) 47 (10.8) 0.10

Conclusion• IADL disability can be a useful tool in predicting

dementia at 1 and 2 year follow-up along with other commonly used clinical measures such as MMSE and memory

• IADL problems are the border between the preclinical stages of dementia and dementia

• Depression is not a risk factor for developing dementia

Comments• Strengths:– Sample size– Prospective design

• Weaknesses:– Pooled IADL items from different questionnaires

• Items might not be closely comparable– Difficult to say which IADL questionnaire should be used – Many patients did not complete the questionnaires

completely• Limited use in clinical practice

– Most of the scales were developed to evaluate patients over time and not for diagnostic purposes • Underestimation of the true diagnostic value of IADL problems

– In some countries or regions, people may visit a memory clinic later in the disease course compared to others