Risk profiles of subtypes of mild cognitive impairment: The Sydney memory and ageing study

Objectives To compare the risk profiles of mild cognitive impairment (MCI) subtypes in a population-based elderly sample. Design Cross-sectional study. Setting The population-based Sydney Memory and Ageing Study. Participants Seven hundred fifty-seven English-speaking, community-dwelling individuals without dementia aged 70 to 90. Measurements Comprehensive neuropsychological assessments were used to diagnose MCI and its subtypes, categorized as amnestic (aMCI) or nonamnestic (naMCI) and as single- (sdMCI) or multiple- (mdMCI) domain. Risk profiles were derived from sociodemographic; lifestyle; and cardiac, physical, mental, and general health data. Whole-sample and sex-specific comparisons between aMCI and naMCI and between mdMCI and sdMCI were made using age- (and sex-) adjusted multiple regressions comprising initially significant univariate factors. Results Risk factors for MCI were presence of the apolipoprotein E (APOE) ε4 allele, heart disease, high homocysteine, poor odor identification ability, low visual acuity, and lower mental activity. The odds of having naMCI rather than aMCI were lower with greater levels of social activity and greater if taking antihypertensives, the latter particularly in men. The odds of naMCI were greater in men taking antidepressants or with a longer 6-meter walk time and in women with hypertension. The odds of having mdMCI rather than sdMCI were greater in participants with a history of depression or having the APOE ε4 allele. Greater odds of mdMCI were also associated with lower mental activity, particularly for women. For men, the odds of mdMCI were greater with the APOE ε4 allele and lower if diagnosed with high cholesterol. Conclusion MCI subtypes exhibit distinctive, sex-dependent risk profiles. This is consistent with MCI subtypes having different etiologies and outcomes and supports the idea that subtyping MCI may offer predictive validity and clinical application.