Association Between Weight Status and Rate of Cognitive Decline: China Health and Nutrition Survey 1997–2018

Abstract

Background There is a close relationship between weight status and cognitive impairment in older adults. This study examined the association between weight status and the trajectory of cognitive decline over time in a population-based cohort of older adults in China. Methods We used data from adults ≥ 55 years participating in the China Health and Nutrition Survey (1997-2018). Underweight (BMI≤18.5 kg/m²), normal weight (18.5-23kg/m²), overweight (23-27.5kg/m²), and obesity (≥27.5kg/m²) were defined using the World Health Organization Asian cutpoints. Global cognition was estimated every 2-4 years through a face-to-face interview using a modified Telephone Interview for Cognitive Status (score 0-27). The association between BMI and the rate of global cognitive decline, using a restricted cubic spline for age and age category, was examined with linear mixed-effects models accounting for correlation within communities and individuals. Results We included 5,992 adults (53% female, mean age of 62 at baseline). We found differences in the adjusted rate of global cognitive decline by weight status (p=0.01 in the cubic spline model). Models were adjusted for sex, marital status, current employment status, income, region, urbanization, education status, birth cohort, leisure activity, smoking status, and self-reported diagnosis of hypertension, diabetes, or MI/stroke. Additionally, significant declines by age in global cognitive function were found for all weight status categories except individuals with obesity. Conclusion In a cohort of adults in China, cognitive decline trajectory differed by weight status. A slower rate of change was observed in participants classified as having obesity.

Association Between Mid-arm Muscle Circumference and Cognitive Function: A Longitudinal Study of Chinese Adults

“…Based on a series of questions about formal and informal occupational employment, employment status was derived and classified as “not currently working” or “currently working,” in either formal or informal employment. 24 Household income was determined from asset and economic activity and individual and household questionnaires from time-use. These values were inflated to 2018 yuan currency for comparability.…”

“… 27 Due to the small number of individuals (11.2%) participating in any leisure activity, this was categorized as “participating in none” or “some leisure activity.” A standard protocol was used to measure height based on Lynch et al’s protocol. Height was measured, “without shoes, to the nearest .1 cm using a portable stadiometer” and weight, “without shoes and in light clothing, to the nearest .1 kg on a calibrated floor scale to generate BMI (kg/m 2 ).” 24 BMI was calculated by dividing the participant’s weight in kilograms by height in meters squared, and was categorized into underweight (<18.5 kg/m 2 , normal weight (18.5-23 kg/m 2 ), overweight (23-27.5 kg/m 2 ) or obesity (≥27.5 kg/m 2 ) based on WHO cut points for Asian populations. 28 A participant was defined as having had a history of a stroke or myocardial infarction, diabetes, or hypertension based on self-report of a doctor’s diagnosis.…”