The impact of behavioral impairment of functional ability in Alzheimer's disease

This study sought to determine the relationship between behavioral disturba nce and functional status in a longitudinally studied sample of patients wi th Alzheimer's disease (AD). One hundred and forty-nine patients meeting NI NCDS-ADRDA criteria for probable AD were followed for an average of 37.3 mo nths, with follow-up assessments every 6 months. Subjects were seen at the Alzheimer's Disease Research Center clinics at the Mt Sinai Medical Center, New York, and the Veterans Affairs Medical Center, Bronx, New York. Measur es included the Physical and Self-Maintenance Scale (PSMS) and Instrumental Activities of Daily Living Scale (IADLS) of Lawton and Brody and the cogni tive and non-cognitive subscales of the Alzheimer's Disease Assessment Scal e (ADAS). For each patient the assessment at which they had their most seve re non-cognitive symptoms as measured by the non-cognitive part of the ADAS (ADAS-NC) was determined. ADAS-NC scores at that assessment were correlate d with IADLS and PSMS scores at the same assessment and at the next assessm ent 6 months later. While there was some modest association of ADAS-NC scor es with functional impairment using pairwise correlation coefficients, none of the correlations remained significant when the severity of cognitive im pairment was controlled statistically. Findings were not significantly chan ged when drug status was controlled. These results suggest that behavioral disturbance, while very troubling to caregivers and patients, does not subs tantially worsen functional ability beyond the contribution of cognitive im pairment in AD. Together with previous results indicating that non-cognitiv e symptoms in AD are episodic and fluctuating rather than progressive, the present data suggest that interventions for non-cognitive disturbances in A D should be viewed as ways to increase patient comfort, safety and ease of care and not as ways to improve functional autonomy. The latter can be achi eved only by improving the progressive cognitive deficits of AD. Copyright (C) 1999 John Wiley & Sons, Ltd.