Hypertension, dyslipidemia, and those combinations are very common in older adults. However, the association between cognitive decline and the combination of hypertension and dyslipidemia in older adults is still controversial. Therefore, we investigate the association between cognitive decline and hypertension, dyslipidemia, and their combination in community-dwelling older people in their 70 s, 80 s, and 90 s in the long-term observational Septuagenarians, Octogenarians, Nonagenarians, Investigation with Centenarians (SONIC) study.
We conducted the Montreal Cognitive Assessment Japanese version (MoCA-J) by trained psychologists and blood testing by medical staff in 1188 participants in their 70 s, 80 s, and 90 s who participated in the SONIC study. Multiple regression analysis was performed in each age cohort to assess these associations at 3-year follow-up after adjusting for covariate factors; sex, BMI, smoking history, Moca-J score at baseline, anti-dyslipidemia medications, anti-hypertensive medications, and diabetes mellitus. After that, we selected individuals with hypertension and then performed the analysis of the association between lipid levels and cognitive function.
At baseline, the percentages of hypertension were 64%(n = 368) in the age 70 s group, 81%(n = 446) in the age 80 s group, and 82%(n = 51) in the age 90 s group, and the percentages of dyslipidemia were 62%(n = 354) in the age 70 s group, 62%(n = 340) in the age 80 s group, and 63%(n = 39) in the 90 s group. The percentages of the participants combined both were 42%(n = 243) in the age 70 s group, 52%(n = 286) in the age 80 s group, and 52%(n = 32) in the 90 s group. The mean MoCA-J score adjusted by the educational level at baseline was 23.94 ± 3.10 in the age 70 s group, 22.25 ± 3.53 in the age 80 s group, and 19.68 ± 3.71 in the 90 s group. By conducting multiple regression analysis, no significant relationship was found between hypertension, dyslipidemia, and their combination and Moca-J score in every age group. On the other hand, high low-density lipoprotein cholesterol (LDL) and high high-density lipoprotein cholesterol (HDL) level resulted in higher Moca-J scores at follow-up in the age 70 s group (LDL: β = 0.074; P = 0.042, HDL: β = 0.096; P = 0.010). Subsequently, only participants with hypertension were selected to compare the association between each lipid level and Moca-J scores, and high HDL resulted in higher Moca-J scores at follow-up (β = 0.059, P = 0.025).
The results suggest that maintaining HDL level may be important in sustaining cognitive function in the community-dwelling older adults population with hypertension.