Interaction between plant-based dietary pattern and air pollution on cognitive function: a prospective cohort analysis of Chinese older adults

Abstract

Background Air pollution is a risk factor for poor cognitive function, while a plant-based dietary pattern is associated with better cognitive function. We aimed to explore their interaction with cognitive function among older adults.Methods We used a prospective cohort of old individuals, including 6525 participants of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), aged 65-110 years and with normal cognition at baseline. Air pollution measurement was derived using satellite-derived annual average fine particulate matter (PM 2.5 ) concentrations based on residential locations. Plant-based diet index (PDI) was calculated using survey responses to assess the dietary pattern. Repeated measures of the Mini-Mental State Examination (MMSE) were utilized to assess cognitive function. We applied the Cox proportional hazard regression to explore the associations and further stratified the analysis by PDI.Findings During a median of 5¢6-year follow-up, 1537 (23¢6%) out of 6525 participants with normal cognition at baseline developed poor cognitive function (MMSE <18). Living in areas with the highest quintile of cumulative PM 2.5 was associated with a 46% increase in the risk of developing poor cognitive function (hazard ratio (HR): 1¢46, 95% confidence interval (CI): 1¢20, 1¢77), compared to those living in areas with the lowest quintile. We observed a significant interaction between cumulative PM 2.5 and PDI (p-interaction: 0¢04), with the corresponding associations of cumulative PM 2.5 being more pronounced among participants with lower PDI (HR: 1¢68, 95% CI: 1¢26, 2¢24) than those with higher PDI (HR: 1¢28, 95% CI: 0¢98, 1¢68).Interpretation Plant-based dietary pattern may attenuate detrimental impacts of PM 2.5 on cognitive function among older adults. Adherence to the plant-based dietary pattern could be used to prevent adverse neurological effects caused by air pollution, especially in developing regions.

The Risk of Hearing Impairment From Ambient Air Pollution and the Moderating Effect of a Healthy Diet: Findings From the United Kingdom Biobank

“…A Mediterranean diet reduced cardiovascular disease mortality risk related to long-term exposure to air pollutants in a large prospective US cohort ( Lim et al, 2019 ). A prospective cohort study of Chinese older adults reported that a plant-based dietary pattern mitigated the adverse effects of air pollution on cognitive function ( Zhu et al, 2022 ).…”

“…In addition, a healthy diet might be beneficial to hearing impairment by protecting microvascular and macrovascular damage to cochlear blood flow ( Appel et al, 2006 ; Fung et al, 2008 ), providing the essential nutrients for an adequate cochlear blood supply ( Yevenes-Briones et al, 2021 ), and reducing inflammation ( Neale et al, 2016 ). According to previous research, dietary patterns could modify the relationship between air pollution and health-related outcomes, such as cardiovascular disease mortality risk ( Lim et al, 2019 ) and cognitive function ( Zhu et al, 2022 ). However, the moderating effect of a healthy diet on the link between hearing impairment and air pollution has not been investigated before.…”

Association of Body Mass Index and Plant-Based Diet with Cognitive Impairment among Older Chinese Adults: A Prospective, Nationwide Cohort Study

“…The MMSE contains a total of 30 items that assess orientation, registration, attention and calculation, recall, and language, with a score range from zero to 30 [ 36 , 37 ]. Use of the MMSE in the CLHLS is well-documented as both reliable and valid [ 22 , 35 , 38 , 39 , 40 , 41 ]. Since MMSE scores might be influenced by education level [ 40 ], participants were defined as cognitively impaired following education-based MMSE cutoff points.…”

“…Use of the MMSE in the CLHLS is well-documented as both reliable and valid [ 22 , 35 , 38 , 39 , 40 , 41 ]. Since MMSE scores might be influenced by education level [ 40 ], participants were defined as cognitively impaired following education-based MMSE cutoff points. Specifically, we used the MMSE scores of 18, 20, and 24 as the cut-off points for subjects with no formal education, only a primary school education (1–6 years), and a middle-school or higher education (>6 years), respectively [ 32 , 40 ].…”

“…Each participant’s dietary information was collected using a simplified food frequency questionnaire (FFQ). The questionnaire has been broadly used, with its reliability and validity both well-supported [ 28 , 40 , 42 , 43 , 44 ]. The simplified FFQ in the CLHLS included 16 food groups which are commonly consumed in China.…”