Cerebral white matter lesions and cognitive function: The Rotterdam Scan Study

Cerebral white matter lesions (WMLs) have been associated with cognitive dy sfunction. Whether periventricular or subcortical WMLs relate differently t o cognitive function is still uncertain. In addition, it is unclear whether WMLs are related to specific cognitive domains such as memory or psychomot or speed. We examined the relationship between periventricular and subcorti cal WMLs and cognitive functioning in 1,077 elderly subjects randomly sampl ed from the general population. Quantification of WMLs was assessed by mean s of an extensive rating scale on 1.5-T magnetic resonance imaging scans. C ognitive function was assessed by using multiple neuropsychological tests f rom which we constructed compound scores for psychomotor speed, memory perf ormance, and global cognitive function. When analyzed separately, both peri ventricular and subcortical WMLs were related to all neuropsychological mea sures. When periventricular WMLs were analyzed conditional on subcortical W MLs and vice versa, the relationship between periventricular WMLs and globa l cognitive function remained unaltered whereas the relationship with subco rtical WMLs disappeared. Subjects with most severe periventricular WMLs per formed nearly 1 SD below average on tasks involving psychomotor speed, and more than 0.5 SD below average for global cognitive function. Tasks that in volve speed of cognitive processes appear to be more affected by WMLs than memory tasks.