Neural response to social but not monetary reward predicts increases in depressive symptoms during the COVID-19 pandemic.

The prevalence of depressive symptoms has increased during the COVID-19 pandemic, especially among those with greater pandemic-related stress exposure; however, not all individuals exposed to pandemic stress will develop depression. Determining which individuals are vulnerable to depressive symptoms as a result of this stress could lead to an improved understanding of the etiology of depression. This study sought to determine whether neural sensitivity to monetary and/or social reward prospectively predicts depressive symptoms during periods of high stress. 121 participants attended pre-pandemic laboratory visits where they completed monetary and social reward tasks while electroencephalogram was recorded. Subsequently, from March to August 2020, we sent eight questionnaires probing depressive symptoms and exposure to pandemic-related stressors. Using repeated-measures multilevel models, we evaluated whether neural response to social or monetary reward predicted increases in depressive symptoms across the early course of the pandemic. Furthermore, we examined whether neural response to social or monetary reward moderated the association between pandemic-related episodic stressors and depressive symptoms. Pandemic-related stress exposure was strongly associated with depressive symptoms. Additionally, we found that blunted neural response to social but not monetary reward predicted increased depressive symptoms during the pandemic. However, neither neural response to social nor monetary reward moderated the association between episodic stress exposure and depressive symptoms. Our findings indicate that neural response to social reward may be a useful predictor of depressive symptomatology under times of chronic stress, particularly stress with a social dimension.

White matter integrity differences in obesity: A meta-analysis of diffusion tensor imaging studies.

Some Diffusion Tensor Imaging studies have shown a loss of white matter (WM) integrity linked to impaired cognitive function in obese individuals. However, inconsistent WM integrity changes have been reported. We aimed to identify which WM tracts show consistent changes with obesity. We conducted a systematic search to find studies examining the association between obesity-related measures and Fractional Anisotropy (FA) or Mean Diffusivity. We performed a meta-analysis with FA datasets using Anisotropic Effect Size-Signed Differential Mapping software. The meta-analysis showed that increased obesity measurements were related to reduced FA in the genu of the corpus callosum. We validated our findings using an independent sample from the Human Connectome Project dataset, which supports lower FA in this region in individuals with obesity compared to those with normal weight (p = 0.028). Our findings provide evidence that obesity is associated with reduced WM integrity in the genu of the corpus callosum, a tract linking frontal areas involved in executive function. Future studies are needed on the mechanisms linking obesity with loss of WM integrity.