High-density lipoprotein cholesterol and cognitive impairment: A U-shaped relationship in China's aging population.

Very high HDL-C levels were associated with lower cognitive scores compared to the lowest HDL-C quartile.

• Compared with Q1 (<35 mg/dL), Q4 had β = -0.622 (95% CI, -0.908 to -0.337) and Q5 had β = -0.322 (95% CI, -0.627 to -0.017).
• The reference group was Q1 (<35 mg/dL).
• Statistical analyses included multiple linear regression, restricted cubic splines, and threshold effect analysis.
• The study included 7,509 participants from the 2011 Chinese Health and Retirement Longitudinal Study.

The relationship between HDL-C and cognitive scores followed a U-shaped (nonlinear) pattern with a turning point at 67.43 mg/dL.

• Below the threshold of 67.43 mg/dL, a 1-SD higher HDL-C was associated with a 0.08-SD higher cognitive score (β = +0.08; 95% CI, 0.06–0.11; p < 0.001).
• Above the threshold of 67.43 mg/dL, a 1-SD higher HDL-C was associated with a 0.07-SD lower cognitive score (β = -0.07; 95% CI, -0.14 to -0.01; p = 0.019).
• The U-shaped relationship was identified using restricted cubic splines and threshold effect analysis.
• The direction of association reversed at the 67.43 mg/dL turning point, indicating a nonlinear relationship.

Cognitive function in the study population was assessed using a composite scale measuring both episodic memory and mental status.

• Data were obtained from the 2011 Chinese Health and Retirement Longitudinal Study.
• The total sample included 7,509 participants.
• The cognitive assessment scale incorporated episodic memory and mental status components.
• The population studied consisted of older adults in China.

The association between lipid profiles and cognitive health is described as nuanced and nonlinear, with implications for strategies to maintain cognitive function in older adults.

• The authors conclude that both very low and very high HDL-C levels are associated with poorer cognitive scores.
• The findings suggest that optimal HDL-C for cognitive health lies at an intermediate level, near the 67.43 mg/dL threshold.
• The authors state that 'understanding these complexities is crucial for developing strategies to maintain cognitive function in older adults.'