Lower TIMP2 concentrations are associated with multiple human conditions: in cerebral spinal fluid its level negatively correlates with microbleeds in Alzheimer’s disease (Duits et al., 2015), in plasma lower TIMP2 is found in patients with frontotemporal dementia (Lorenzl et al., 2008), and in blood TIMP2 negatively correlates with cognitive deficits in recurrent depressive disorder (Bobińska et al., 2016). This evidence concerns the gene TIMP2 and major depressive disorder.