Functional decline in Alzheimer's disease: a longitudinal study.

OBJECTIVE: To assess the reliability of activities of daily living (ADL) measures and determine the rate and pattern of longitudinal ADL change in patients with Alzheimer's disease (AD).
DESIGN: Longitudinal study with evaluations every 6 months.
SETTING: Alzheimer's Disease Research Center Clinics at Mount Sinai Medical Center, New York, and the Veterans Affairs Medical Center, Bronx, New York. PATIENTS: 104 patients meeting NINCDS-ADRDA criteria for probable AD were followed an average of 31 months. MEASUREMENTS: Physical Self-Maintenance Scale (PSMS) and Instrumental Activities of Daily Living Scale (IADLS) of Lawton and Brody and the Blessed Test of Information, Memory, and Concentration.
RESULTS: For men there was inconsistency over time in the decision about whether or not some IADLS items such as "Laundry" were appropriate for a given patient. Test-retest and inter-rater reliabilities were high for all PSMS items and for IADLS items that were judged to be appropriate. IADLS scores changed an average of 2.06 (+/- 3.27) points annually, and change scores were smaller for patients with severe dementia. PSMS scores changed an average of 2.44 (+/- 3.87) points annually with virtually all change occurring in severely demented patients. There was a marked ceiling effect for the IADLS and a curvilinear relationship of PSMS annual change with PSMS baseline.
CONCLUSIONS: Both PSMS and IADLS measures can be reliable in AD patients, but better IADLS items for males need to be developed. IADLS scores are sensitive to change in mild and moderately demented AD patients, while PSMS scores are sensitive to change in more severely demented patients.