Arteriolosclerotic leucoencephalopathy in the elderly and its relation to white matter lesions in Binswanger's disease, multi-infarct encephalopathy and Alzheimer's disease.

Arteriolosclerotic leucoencephalopathy in the elderly (ALE) is characterized by white matter lesions associated with atherosclerosis and arteriolosclerosis. Mild lesions are focal and probably represent early status cribosus or incomplete lacunar infarcts. Moderate and severe lesions are diffuse areas of demyelination in the centrum semiovale in which lacunar infarcts are seldom observed. The incidence of ALE in a consecutive necropsy series of 50 cases (mean age 62.6 +/- 13.1 years) was 52%, it was rare in the fourth and fifth decades but increased thereafter to reach a prevalence of 100% at the age of 80 years. Mild lesions occurred in 19 patients and lesions were moderate or severe in 7 (14%). The mean age was higher in this group (74.7 +/- 7.6 years) than in patients with white matter changes as a whole. Dementia occurred only in 3 patients with moderate or severe ALE. These data suggest that (a) ALE is common in old age and is probably the cause of leuko-araiosis in most CT scans in the elderly; (b) ALE may be asymptomatic; (c) the severity of white matter changes may be not related to the severity of neurological deficits; and (d) multiple lacunar infarcts or associated degenerative diseases (i.e., Alzheimer's disease) may be the main cause of dementia in patients with ALE. White matter lesions in ALE, Binswanger's disease, transition areas in multi-infarct encephalopathy (MIE) and Alzheimer's disease (AD) are similar in morphology and are probably the result of a subacute hypoperfusion/hypoxic process. Increased arterial blood pressure is a frequent risk factor in ALE, Binswanger's disease and MIE, whereas congophilic angiopathy of the meningeal and cortical vessels, in addition to mild or moderate arteriolar hyalinosis in the white matter, may play a role in the pathogenesis of incomplete infarctation of the white matter in patients with AD.