A possible mechanistic overlap between mood disorders and autoimmune diseases has previously been proposed, with extravasation of activated CD8+ T cells in the peripheral circulation of BD patients reflecting T cell-mediated WM abnormalities in the brain parenchyma and a link between WM pathology and CD8+ T cell activation has been reported in other inflammatory diseases such as multiple sclerosis [65, 115]. Here, CD8A is linked to multiple sclerosis.