A randomized controlled trial examining the effects of behavioral weight loss treatment on hippocampal volume and neurocognition

Background/purpose: Obesity in midlife is an established risk factor for dementia. In middle-aged adults, elevated body mass index (BMI) is associated with lower neurocognition and smaller hippocampal volumes. It is unclear whether behavioral weight loss (BWL) can improve neurocognition. The purpose of this study was to evaluate whether BWL, compared to wait list control (WLC), improved hippocampal volume and neurocognition. We also examined if baseline hippocampal volume and neurocognition were associated with weight loss. Methods: We randomly assigned women with obesity (N = 61; mean±SD age=41.1 ± 9.9 years; BMI=38.6 ± 6.2 kg/m²; and 50.8% Black) to BWL or WLC. Participants completed assessments at baseline and follow-up including T1-weighted structural magnetic resonance imaging scans and the National Institutes of Health (NIH) Toolbox Cognition Battery. Results: The BWL group lost 4.7 ± 4.9% of initial body weight at 16–25 weeks, which was significantly more than the WLC group which gained 0.2 ± 3.5% (p < 0.001). The BWL and WLC groups did not differ significantly in changes in hippocampal volume or neurocognition (ps>0.05). Baseline hippocampal volume and neurocognition scores were not significantly associated with weight loss (ps>0.05). Conclusions and implications: Contrary to our hypothesis, we found no overall benefit of BWL relative to WLC on hippocampal volumes or cognition in young- and middle-aged women. Baseline hippocampal volume and neurocognition were not associated with weight loss.