The relationship between trajectories of serum lipids and cognitive impairment in middle aged and elderly: A 6-year prospective cohort study in Xi'an, China.

BACKGROUND

Hyperlipidemia has been linked to cognitive impairment (CogI) caused by Alzheimer's disease and vascular disease. Nevertheless the relationship between long-term trajectories of serum lipids and the risk of developing CogI is still lacking.

METHODS

Research enrolled participants aged 40 years or older in the suburbs of Xi'an, China and conducted follow-ups every two years from 2014 to 2020. Fasting serum lipid (including total cholesterol, TC; triglyceride, TG; high density lipoprotein, HDL-c; low density lipoprotein, LDL-c) levels were tested. Those with normal cognition at baseline and diagnosed with MCI or dementia during follow-up were defined as having new-onset CogI. We used group-based trajectory model for serum lipid trajectory classification, and multivariable logistic regression models to investigate the relationship between long-term serum lipids trajectories and CogI.

RESULTS

Our final sample included 1268 participants. There were 33 (2.6%) new-onset CogI of whom 20 met the criteria for MCI and 13 met the criteria for dementia during the follow-up. Trajectories of TC and LDL-c were divided into three categories (low, medium and high level) respectively; lgTG and HDL-c were divided into low and high level respectively. Univariate analysis showed that the incidence rate of CogI in low TC group (3.4%) or high TC group (4.3%) was higher than that in medium TC group (1.5%). Multivariable logistic regression analysis showed that compared to medium level, the risk of developing CogI was increased for both low TC level (OR=2.679 [95% CI, 1.140-6.295]) and high TC level (OR=2.828 [95% CI, 0.927-8.624]). Other lipid trajectory levels were not associated with the risk of developing CogI.

CONCLUSIONS

Long-term low or high TC levels may be a predictive factor for the risk of CogI.