Number of completed exercise sessions is associated with slower brain atrophy in MCI over 12 months in the EXERT trial

Abstract

AbstractBackgroundMid‐ and late‐life exercise has been associated with lower dementia risk. The EXERT trial tested whether aerobic training (AX), compared to stretching/balance/range‐of‐motion training (SBR), could slow cognitive decline in MCI. While no difference was detected between exercise arms, EXERT participants overall showed little cognitive change over 12 months. It is possible that the amount of exercise, rather than the type, may be protective against decline. In this exploratory, post‐hoc analysis of EXERT data, we assessed whether intervention adherence, operationalized as the number of supervised exercise sessions completed, was associated with slower brain atrophy over 12 months.Method194 EXERT participants with baseline and follow‐up MRI were included in this analysis. For each participant, the number of supervised exercise sessions of at least 40 minutes in duration completed during the first 12 months was determined. MRI data were processed using FreeSurfer. Repeated measures ANOVAs were conducted using regional volume or thickness as the dependent variable, and the interaction between number of sessions (continuous scale) and study visit as the independent variable. Baseline age and sex, as well as their interactions with time were included in the model. FDR‐adjusted p‐values <0.05 were considered significant.ResultGreater number of sessions completed was associated with less brain atrophy over 12 months in the hippocampus and parahippocampus, and less ventricular expansion in the lateral and inferior lateral ventricles (Table 1, Figure 1; FDR‐corrected p<0.05 for interaction term). Results remained unchanged when including exercise type (AX vs. SBR), baseline CDR‐SB, or baseline plasma Aβ42/40 in the model. Findings were similar when analyses were restricted to participants who completed the study prior to the onset of the COVID‐19 pandemic.ConclusionOur results show that higher adherence to a supervised exercise intervention over 12 months was associated with reduced brain atrophy in adults with amnestic MCI. These findings were obtained in post‐hoc, exploratory analyses, so causality should be interpreted with caution. EXERT was supported by the Alzheimer’s Disease Cooperative Study and funded by the National Institutes of Health grant U19‐AG010483.