The purpose of this study was to assess the cross-sectional prevalence and characteristics of anxiety among patients with Alzheimer's disease (AD), as compared with patients with frontotemporal dementia (FTD), patients with vascular dementia (VaD), and normal control subjects. The authors used the anxiety subscale of the Neuropsychiatric Inventory (NPI), an instrument with established reliability and validity, to compare patients. Patients were identified in a query of the UCLA Alzheimer's Disease Center database and included 115 patients with probable AD, 43 patients with VaD, 33 patients with FTD, and 40 normal, elderly control subjects. Descriptive statistics were generated, and partial correlations, controlling for Mini-Mental State Examination (MMSE) score, were performed between the anxiety subscale and other behavioral features as measured by the NPI and the Functional Activities Questionnaire (FAQ). Relationships between cognitive status (as indicated by MMSE score) and anxiety were explored. Anxiety was reported more commonly in patients with VaD and FTD than in patients with AD. These differences remained significant (P<0.01) in an analysis of variance (ANOVA) after adjusting for age, age at onset, educational level, and MMSE score. In AD, anxiety was inversely related to MMSE score (i.e., worse with more severe dementia), was more prevalent among patients with a younger age at onset (under age 65), and correlated with disability as measured by the FAQ score. These data suggest that anxiety is common among patients with diverse forms of dementia. In AD, anxiety is most common in those with more severe cognitive deterioration and an earlier age at onset.