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

Abstract

To examine the association of body mass index (BMI) and a plant-based diet (PBD) with cognitive impairment in older adults, this cohort study used data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), a national, community-based, longitudinal, prospective study in China. Cognitive function was evaluated via the Mini-Mental State Examination (MMSE). Diet was assessed using a simplified food frequency questionnaire (FFQ), and PBD patterns were estimated using the overall plant-based diet index (PDI), the healthful plant-based diet index (hPDI), and the unhealthful plant-based diet index (uPDI). BMI was measured objectively during the physical examination. Cox proportional hazard models and restricted cubic spline analyses were used. A total of 4792 participants with normal cognition at baseline were included, and 1077 participants were identified as having developed cognitive impairment during the 24,156 person-years of follow-up. A reverse J-shaped association was observed between BMI and cognitive impairment (p = 0.005 for nonlinearity). Participants who were overweight (HR = 0.79; 95% CI 0.66–0.95) and obese (HR = 0.72; 95% CI 0.54–0.96) had a decreased risk of cognitive impairment, while those who were underweight (HR = 1.42; 95% CI 1.21–1.66) had an increased risk. Lower PDI, lower hPDI, and higher uPDI were associated with an increased risk of cognitive impairment (HR = 1.32; 95% CI 1.16–1.50 for PDI; HR = 1.46; 95% CI 1.29–1.66 for hPDI; HR = 1.21; 95% CI 1.06–1.38 for uPDI). The protective effect of being overweight on cognitive impairment was more pronounced among participants with a higher PDI (HR = 0.74; 95% CI 0.57–0.95) than those with a lower PDI (HR = 0.87; 95% CI 0.67–1.12), among participants with a higher hPDI (HR = 0.73; 95% CI 0.57–0.94) than those with a lower hPDI (HR = 0.93; 95% CI 0.72–1.10), and among participants with a lower uPDI (HR = 0.61; 95% CI 0.46–0.80) than those with a higher uPDI (HR = 1.01; 95% CI 0.80–1.27). Our results support the positive associations of overweight status, obesity, an overall PBD, and a healthful PBD with cognitive function in older adults. A lower adherence to an overall PBD, a healthful PBD, and a higher adherence to an unhealthful PBD may attenuate the protective effect of being overweight on cognitive function.

Sex-Specific Association of Body Mass Index with Hippocampal Subfield Volume and Cognitive Function in Non-Demented Chinese Older Adults

“…BMI also negatively affects the cognitive performance of fibromyalgia patients [81]. A cohort study from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) supports the positive associations of overweight status with cognitive function in older adults, particularly in those with a higher plant-based diet index [10]. It should be pointed out that other factors, such as physical activity, may also play a role in modifying the association between BMI and cognition in the elderly.…”

“…Maintaining an overweight status (body mass index (BMI) ≥ 25 kg/m 2 ) during midlife was found to increase the risk of cognitive impairment and dementia in later life [9]. Conversely, being overweight in the later stages of life may be associated with a reduced risk of dementia [8,10]. Nevertheless, the precise mechanisms underlying these associations remain unclear [11].…”

Association between Plant-based Diet and Risk of Chronic Diseases and All-Cause Mortality in Centenarians in China: A Cohort Study

“…Taking into consideration the dietary patterns and characteristics of Chinese older adults, as well as referring to dietary scoring methods proposed by some scholars, we selected a total of 16 types of food as indicators for dietary assessment [ [22] , [23] , [24] ]. These indicators were classified into 3 categories: HPF, which included 8 types of food such as whole grains, vegetable oil, fresh fruits, fresh vegetables, legumes, garlic, nuts, and tea; unhealthy plant-based foods, which consisted of 3 types of food namely refined grains, preserved vegetables and sugar; and animal-based foods, which included 5 types of food namely meat, fish and aquatic products (fish), milk or dairy products, eggs, and animal fat.…”

“…Our objective was to assess the relationship between chronic diseases and all-cause mortality and different dietary patterns, using survey data collected from centenarians in China [ 22 ]. Following the common classification methods used in current research, we have categorized 16 types of food intake frequencies into 3 composite dietary patterns [ 23 , 24 ]: plant-based dietary index (PDI), healthy plant-based dietary index (hPDI), and unhealthy plant-based dietary index (uPDI). In addition, we have also calculated the intake scores of the 3 food categories, namely the healthy plant-based foods index (HPF), the unhealthy plant-based foods index (uHPF), and the animal-based foods index (AF), on the basis of the frequency at which different categories of plants are consumed.…”

Dietary Patterns and Nutritional Value in Non-Communicable Diseases

“…Interestingly, all plant-based and anti-inflammatory diets improved pain measurements, whereas not all gluten-free or elimination/restrictive diets showed statistical significance in pain improvement [ 16 ]. The significance of plant-based diets also emerged in a study of cognitive impairment in Chinese adults [ 17 ]. In this longitudinal prospective study, 1077 out of 4792 participants developed cognitive impairment, which showed a reverse J-shaped association with BMI, meaning that overweight and obese participants had a decreased risk, whereas underweight participants had an increased risk of cognitive impairment.…”