Individuals with bipolar disorder (BD) are at heightened risk for obesity, a condition linked to neuroanatomical changes such as hippocampal atrophy and cortical thinning. In our previous longitudinal study we saw that weight gain was associated with hippocampal atrophy, which was more pronounced in BD than healthy controls (HC). Given established structural and functional connections between the hippocampus and cortex, we investigated whether weight gain or hippocampal atrophy contributed to cortical thinning.
We conducted the largest longitudinal study on this topic in collaboration with the ENIGMA consortium including 13 sites, with 233 BD and 701 HC participants. Using longitudinal T1-weighted MRI scans, collected an average of 2.84 years apart, we applied linear mixed-effects models to evaluate associations among BMI, hippocampal volume, and cortical structure over time. We found that hippocampal atrophy associated with weight gain was significantly related to cortical thinning in 32/34 regions. Hippocampal atrophy over time but not weight gain were associated with cortical thinning. These results were evident in both HC and BD individuals
It is interesting that although obesity was not directly related to cortical thinning, it was related to hippocampal atrophy which in turn was related to cortical thinning. The effects of obesity on cortical thickness, as documented in other studies could be indirect and related to obesity related subcortical atrophy. These mechanisms of brain change may be a function of obesity even in HC. These results are clinically relevant since they present weight management as a preventative measure against both subcortical and cortical atrophy.
Title: Indirect effect of weight gain on cortical thinning via hippocampal atrophy: Longitudinal ENIGMA study in 934 individuals
Speaker: Julia Fraiha Pegado, Canada
Breaking Hot Topics webinar series: Following a record number of submissions to the Breaking Hot Topics Symposium at the 38th ECNP Congress in Amsterdam, the ECNP is proud to launch the Breaking Hot Topics webinar series. This new online series features selected runner-up presentations that showcase the most current and compelling science in neuropsychopharmacology.
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