['To determine the relation between concomitant small cerebral infarction and clinical progression of Alzheimer disease (AD).', 'A retrospective clinicopathologic study of patients with AD.', "We searched the databases of the University of California, San Diego, Alzheimer's Disease Research Center, La Jolla, for patients with an autopsy diagnosis of definite AD with or without a concomitant small cerebral infarction. Clinical and neuropsychologic data obtained during longitudinal follow-up were available for 201 subjects with AD neuropathologic features and 36 with AD and concomitant cerebral infarcts (volume, < 10 cm(3)). The rates of cognitive decline on the Mini-Mental State Examination and the Dementia Rating Scale were each calculated and compared between the 2 groups.", 'The age at death was significantly (P = .05) higher and the Braak stage was lower in patients with mixed AD and infarct pathological features compared with those with AD pathological features only. The rate of cognitive decline over time was not significantly (P > or = .20 for all) different between the 2 groups. There was a trend for the presence of a cerebral infarct to be associated with more severe clinical dementia (P =.08) as measured by the Dementia Rating Scale, but no such trend for the Mini-Mental State Examination.'] Do small concomitant vascular lesions influence rates of cognitive decline in patients with Alzheimer disease?