Relationship of leukoaraiosis to cognitive decline and cognitive aging

Leukoaraiosis (LA) is a common finding on MRI scans of the elderly. However, its exact relationship to cognitive decline and dementia is in dispute. Because LA involves the paracallosal white matter, we sought to determine if LA, uncomplicated by ischemic lesions or complaints of cognitive impairment, is associated with cognitive loss or difficulties with interhemispheric integration of behavioral functions.

Two hundred fifty-seven MRI scans with deep white matter changes were screened. After a chart review, 38 patients had uncomplicated LA, and 31 gave informed consent to undergo cognitive and behavioral testing.

LA severity was not related to any of the cognitive or behavioral assessments. However, some dependent measures showed medium effect sizes that were in keeping with published findings, indicating that LA has a marginal impact on cognition. In comparison, robust relationships with age were found for certain tasks, suggesting that our cohort size was sufficient to detect meaningful clinical relationships.

Based on statistical interpretations using effect sizes, LA severity may be better viewed as a biomarker for physiological brain aging that is in advance of chronological age, leaving the elderly individual at greater risk for developing dementia.