Fifty-four patients with Alzheimer's disease (AD) were examined for white-matter lesions (WMLs) using computerized tomography. WMLs were more frequent in late-onset AD (LAD) (26/34-76%) than in early-onset AD (EAD) (5/20-25%) (p less than 0.0001), in AD without parietal predominance (10/11-91%) (p less than 0.005) than in AD with parietal predominance (5/15-33%), and in AD with confusional symptoms (11/12-92%) than in AD without confusional symptoms (4/14-29%) (p less than 0.001). The supine systolic blood pressure was higher in AD with WMLs (151 +/- 20) than in AD without WML (139 +/- 22) (p less than 0.05). AD patients with WMLs, but not those without WMLs, had a higher mean albumin ratio (7.5 +/- 2.7) than healthy controls (5.7 +/- 2.1) (p +/- 0.005). The finding of less focal (= less parietal) symptomatology in AD with WMLs than without WMLs suggests clinical significance of WMLs in AD, while the relations between blood pressure, BBB function and WMLs support the hypothesis of a vascular pathogenesis.