Cognitive consequences of multiple lacunes and leukoaraiosis as vascular cognitive impairment in community-dwelling elderly individuals.

The aim of our study was to investigate the effects of silent brain lesions on cognitive function of community-dwelling elderly individuals. Brain magnetic resonance imaging and other medical examinations were performed on 350 nondemented elderly individuals (121 male and 229 female, average age 72.4 years) who resided in the rural community of Sefuri Village, Saga, Japan. The mini mental state examination and modified Stroop test (MST) were used to identify cognitive impairment. White matter lesions (WMLs) and cerebral atrophy on magnetic resonance imaging were measured quantitatively. Multivariate analyses were done using a logistic regression model with a software package. Cognitive impairment defined by mini mental state examination score less than 24 was present in 55 individuals (15.7%). They had a lower educational level, significantly larger quantity of WMLs, and more remarkable cerebral atrophy. Frontal lobe dysfunction was detected in 52 individuals (14.9%) through prolonged MST score (>36 seconds). Impaired frontal lobe function was related to number of silent lacunar infarcts, larger WMLs, and more prominent cerebral atrophy. MST score in individuals with two or more infarcts was significantly more prolonged compared with MST score in those without infarction. These results suggest that WMLs may cause rather diffuse cognitive decline, whereas multiple lacunar infarcts are specifically involved in frontal lobe dysfunction. Silent ischemic lesions in apparently healthy elderly individuals seem to form a distinctive group of people with vascular cognitive impairment without dementia. This group should be the primary target of prevention of vascular dementia.