Changes in Plant-Based Dietary Quality and Subsequent Risk of Cognitive Impairment Among Older Chinese Adults: a National Community-Based Cohort Study

Background: It is unclear how changes in plant-based dietary quality are linked to the subsequent risk of cognitive impairment.

Objectives: This study aims to evaluate this relationship using data from the Chinese Longitudinal Healthy Longevity Survey.

Methods: A total of 6662 participants free of cognitive impairment in 2008 were included and followed ≤2018. Plant-based dietary quality was assessed by 3 indices: overall plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI). Changes in plant-based diet quality from 2008 to 2011 were classified into quintiles. In addition, we assessed incident cognitive impairment (from 2011 to 2018) by using the Mini-Mental State Examination. Cox proportional-hazards models were performed.

Results: We recorded 1571 incident cases of cognitive impairment during a median of 10 y of follow-up. Compared with participants whose plant-based diet had no change or was relatively stable over 3 y, the full-adjusted hazard ratios (HRs) with 95% confidence intervals (CI) for cognitive impairment were 0.77 (0.64, 0.93), 0.72 (0.60, 0.86), and 1.50 (1.27, 1.77) among participants with a large increase in PDI, hPDI, and uPDI, respectively. The HRs with 95% CI were 1.22 (1.02, 1.44), 1.30 (1.11, 1.54), and 0.80 (0.67, 0.96) among participants with a large decrease in PDI, hPDI, and uPDI, respectively. Every 10-point increase in PDI and hPDI was associated with a 26% and 30% lower risk of cognitive impairment, whereas every 10-point increase in uPDI was associated with a 36% higher risk.

Conclusions: Older adults with increased adherence to an overall plant-based diet and a healthful plant-based diet over 3 y have a lower risk of cognitive impairment, whereas those with increased adherence to an unhealthy plant-based diet had a higher risk of cognitive impairment.