Low Body Mass Index in demented outpatients.

In order to determine the association between dementia and low body weight in outpatients, Body Mass Index (BMI) was evaluated prospectively in 346 frail elderly outpatients presenting for comprehensive geriatric assessment. Patients were categorized into four groups (cognitively intact, dementia of the Alzheimer's type (DAT), other dementia, and patients with depressive symptoms). Patients were assessed for severity of dementia by the Clinical Dementia Rating scale. Differences between groups for various clinical parameters were evaluated using an analysis of variance and Duncan's Multiple Range Test. Patients with dementia, regardless of etiologic type or severity, and patients with depressive symptoms had BMI's greater than or equal to 10% lower than the cognitively intact patients. BMI was positively correlated with Instrumental Activities of Daily Living (IADL) but not Activities of Daily Living (ADL) or Mini-Mental State Exam (MMSE) score. Low BMI was not associated with increased physical illness. In fact, in the subset of patients with DAT, lower BMI correlated with significantly lesser amounts of comorbid physical illness. Finally, compared to cognitively intact outpatients, patients with DAT appeared to be physically healthier despite their having a lower BMI. These results suggest an association between dementia and low BMI. On the other hand, the presence of comorbid physical illness, a common focus of evaluation in these patients, was not more common in those patients with lower BMI's.