Adverse Lipid Profiles Are Associated with Lower Dementia Risk in Older People.

ABSTRACT

OBJECTIVE: Midlife dyslipidemia is associated with higher risk of dementia in late-life dementia, but the impact of late-life dyslipidemia on dementia risk is uncertain. This may be due to the large heterogeneity in cholesterol measures and study designs employed. We used detailed data from a large prospective cohort of older persons to comprehensively assess the relation between a broad range of cholesterol measures and incident dementia, addressing potential biases, confounders, and modifiers. DESIGN: Post hoc observational analysis based on data from a dementia prevention trial (PreDIVA). SETTING AND PARTICIPANTS: 3392 community-dwelling individuals, without dementia, aged 70-78 years at baseline (recruited between June 2006 and March 2009). METHODS: Total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, and apolipoprotein A1 and B were assessed. Over a median of 6.7 years' follow-up, dementia was established by clinical diagnosis confirmed by independent outcome adjudication. Hazard ratios (HRs) for dementia and mortality were calculated using Cox regression. RESULTS: Dementia occurred in 231 (7%) participants. One-SD increase in LDL/HDL conveyed a 19% (P = .01) lower dementia risk and a 10% (P = .02) lower risk of dementia/mortality combined. This was independent of age, cardiovascular risk factors, cognitive function, apolipoprotein E genotype, and cholesterol-lowering drugs (CLD). This association was not influenced by the competing risk of mortality. Consistent and significant interactions suggested these associations were predominant in individuals with low body mass index (BMI) and higher education. CONCLUSIONS AND IMPLICATIONS Dyslipidemia in older individuals was associated with a lower risk of dementia. Low BMI and higher education level mitigate poor outcomes associated with dyslipidemia. These findings suggest that a different approach may be appropriate for interpreting lipid profiles that are conventionally considered adverse in older adults. Such an approach may aid predicting dementia risk and designing intervention studies aimed at reducing dementia risk in older populations.