Determinants of functional status in Alzheimer's disease and vascular dementia

Functional decline is a core feature of dementia, but its relationship with cognitive impairment is not always predictable. In the present study, we l ooked for the cognitive and non-cognitive determinants of the functional st atus in subjects with Alzheimer's disease (AD) and vascular dementia (VD). We studied 85 patients referred to our outpatient clinic: 44 affected by AD and 41 by VD (NINCDS-ADRDA, and NINDS-AIREN criteria, respectively). Cogni tive impairment was measured with mini mental state examination (MMSE) and with an extended neuropsychological battery; functional impairment with Bar thel index (BI), basic activities of daily living (BADL) and instrumental a ctivities of daily living (IADL); comorbidity with index of disease severit y (IDS). Depressive symptoms were evaluated by the geriatric depression sca le (GDS), behavioral disorders by the UCLA neuropsychiatric inventory (NPI) . The two groups were matched for gender, age, educational level, MMSE, GDS and NPI. VD patients compared to AD showed a lower BI, a greater comorbidi ty, a more frequent presence of neurological gait disorders at the physical examination and a lower score at the tasks assessing selective attention a nd verbal fluency. In the multivariate analysis, measures of selective atte ntion and of picture naming, together with the presence of neurological gai t disorders, were independently related to BI. In our case-mix, VD patients were more disabled than those with AD, in spite of the same MMSE score, an d showed more severe attentional defects.