MFN2 and depressive symptom measurement: Mitochondrial dysfunction has increasingly been linked to neuropsychiatric disorders,73,74 which often exhibit structural changes in neurons, such as dendritic atrophy and spine loss.75,76 Recent evidence further supports a strong link between mitochondrial dynamics and psychiatric conditions, including anxiety and depression.14,77 For instance, high-anxiety animal models show reduced mitofusin 2 levels specifically in medium spiny neurons of NAc, leading unexpectedly to larger, rounded mitochondria rather than the smaller, fragmented structures typically associated with impaired fusion.