Leisure activity engagement attenuates the risks of cognitive impairment induced by unhealthy plant-based diets: a nationwide cohort study.

Objective: We intended to reveal the joint effects between LAE and uPDI on cognition in Chinese older adults.

Methods: Data were collected from the Chinese Longitudinal Healthy Longevity Survey. In total, 10,617 individuals aged 65 years and above without cognitive impairment or dementia at baseline were enrolled in 2008 and followed up in 2011, 2014, and 2018. The uPDI and the scores of LAE were derived from survey responses, and both were categorized into three groups (low, intermediate, and high). Individuals with a Mini-Mental State Examination (MMSE) score lower than 18 were considered to have cognitive impairment. Cox proportional hazards models were employed to explore the joint association of uPDI and LAE on cognitive impairment, followed by restricted cubic spline (RCS) to observe the effects of the continuous-type variable of uPDI and the scores of LAE on the risk of cognitive impairment. Stratified analysis was applied to examine the association of LAE with cognitive impairment in uPDI groups (high uPDI vs. low uPDI).

Results: Compared to participants maintained low scores of LAE and high uPDI, those who maintained high scores of LAE and low uPDI had a decreased risk of cognitive impairment (HR = 0.52, 95% CI, 0.43-0.62). The findings of the stratified analysis demonstrated that the protective effects of high scores of LAE on cognition was pronounced in individuals with low uPDI (HR = 0.61, 95% CI: 0.47-0.79) and those with high uPDI (HR = 0.63, 95% CI: 0.51-0.78).

Conclusions: In this cohort study, a higher score of uPDI, which indicated higher intake of salt-preserved vegetables, sugars, and refined grains, was associated with an increased risk of cognitive impairment, whereas this association may be mitigated by regular engagement in leisure activities.