Association of Blood Lipoprotein Levels With Incident Alzheimer Disease in Community-Dwelling Individuals

BACKGROUND AND OBJECTIVES: Cardiovascular risk factors are important contributors to the risk of Alzheimer disease (AD). To further explore the physiologic links between cardiovascular health and AD risk, we studied the associations between various blood lipoprotein levels and AD risk in community-dwelling older adults. METHODS: This longitudinal analysis included participants aged 60 years or older without prevalent dementia and with available cognitive follow-up and lipoprotein marker data from the Framingham Heart Study. Levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), small dense LDL-C (sdLDL-C), lipoprotein a (Lp(a)), apolipoprotein B (ApoB), and the ApoB isoform ApoB48 were measured in blood samples obtained from 1985 to 1988. Participants were under surveillance for incident AD until 2020. AD diagnosis was based on standard clinical criteria. The relationships between blood lipoprotein levels (expressed as both continuous variables and quartiles) and AD incidence were examined using Cox proportional hazard models adjusted for baseline age and sex. RESULTS: A total of 822 participants (mean [SD] age 72.5 [3.7] years, 538 [65.5%] women) were followed for a median (interquartile range) of 12.55 (7.34-15) years, during which 128 participants developed incident AD. An increase of 1 standard deviation unit (SDU) in ln(sdLDL-C) concentration was associated with a 21% increase in the risk of incident AD (hazard ratio [HR] 1.21, 95% CI 1.01-1.45), whereas a 1-SDU increase in ln(ApoB48) concentration was associated with a 22% decrease in the risk of incident AD (HR 0.78, 95% CI 0.66-0.93). Participants in the first HDL-C quartile were 44% less likely to develop AD compared with those in the second, third, and fourth HDL-C quartiles (HR 0.56, 95% CI 0.33-0.95). Participants with sdLDL-C concentrations below the median were 38% less likely to develop AD compared with those with sdLDL-C concentrations above the median (HR 0.62, 95% CI 0.44-0.86). DISCUSSION: Lower sdLDL-C and higher ApoB48 concentrations were associated with a lower AD risk. In addition, individuals with the lowest HDL-C concentrations were less likely to develop AD compared with the remaining sample. These findings underscore links between lipoprotein metabolism pathways and AD risk, emphasizing the potential role of blood lipoprotein markers in AD risk stratification and of lipid modification strategies in dementia prevention.