Sedentary pattern, brain health, and cognitive function in rural‐dwelling older adults: A population‐based study

Abstract

AbstractBackgroundSedentary behavior is distinct from low moderate‐to‐vigorous physical activity and is associated with a range of adverse health conditions. Population‐based studies have rarely examined the associations of objectively‐measured sedentary parameters, structural brain markers, and cognition among older adults.MethodsThis population‐based study included 2019 rural‐dwelling older adults (age ≥60 years, 59% women) who were free of dementia derived from MIND‐China baseline participants. In 2018‐2020, sedentary behavior parameters were measured using accelerometers. We used a neuropsychological test battery to assess global and domain‐specific cognitive function (memory, language, attention, and executive function). Volumes of total brain tissue, white matter hyperintensities, total grey matter, total white matter, ventricles, and hippocampus were assessed on the magnetic resonance imaging in a subsample (n = 1009). We used the general linear models, restricted cubic splines, and mediation models to examine the associations of sedentary parameters, structural brain markers, and cognitive measures, and the isotemporal substitution models to estimate associations of replacing sedentary time with physical activity.ResultsIn the total sample, adjusting for multiple confounders and MVPA, longer mean sedentary bout duration was linearly associated with lower z‐scores of global cognition, memory, and language, whereas the linear association of greater total sedentary time with poorer global cognition, memory, and language existed only among long‐sedentary individuals (>10.2 hours/day); Having more breaks per sedentary hour or replacing 30‐minute sedentary time with the same amount of physical activity was significantly associated with higher cognitive z‐scores (P<0.05). In the MRI subsample, simultaneously or separately entering multiple structural brain markers into the mediation models substantially attenuated the associations between mean sedentary bout duration and cognitive z‐scores.ConclusionIn the rural‐dwelling Chinese older adults, the association of prolonged uninterrupted sedentary time with poor cognition is largely mediated by structural brain markers and frequent breaks in sedentary time are associated with brain health.