White matter lesions on brain magnetic resonance imaging scan and 5-year cognitive decline: the Honolulu-Asia aging study.

OBJECTIVES

To study white matter lesions (WMLs) and 5-year cognitive decline in elderly Japanese-American men.

DESIGN

Longitudinal cohort study.

SETTING

Population-based study in Honolulu, Hawaii.

PARTICIPANTS

Japanese-American men aged 74 to 95 from the Honolulu-Asia Aging Study (HAAS) who were free of prevalent dementia, underwent a protocol brain MRI scan at the fifth HAAS examination (1994-1996), and returned for cognitive testing 5 years later (N=267).

MEASUREMENTS: WMLs were dichotomized as present (grade 3-9, 38.2%) or absent (grade 1-2, 61.8%). Cognitive function was measured using the Cognitive Abilities Screening Instrument (CASI), and 5-year cognitive decline was defined as a drop in CASI score of 12 points or more (1 standard deviation).

RESULTS

Men with WMLs on MRI at baseline were significantly more likely to experience cognitive decline at 5 years than those without (22.4% vs 34.4%, P=.03). Using multiple logistic regression, adjusting for age, education, apolipoprotein (Apo)E4 allele, large or small infarcts on MRI, baseline CASI score, and hypertension, those with WMLs were significantly more likely to develop 5-year cognitive decline (odds ratio=2.00, 95% confidence interval=1.10-3.65, P=.02). This association was stronger in men who were cognitively intact and free of the ApoE4 genotype and clinical stroke at baseline.

CONCLUSION

Presence of WMLs on MRI was significantly associated with higher odds of 5-year cognitive decline in older Japanese-American men. Presence of WMLs may help identify people at risk for developing dementia, who may benefit from early intervention.