Indeed, if studies such as Pomara et al. [30] proposed reductions in CSF levels of amyloid in patients with MDD, similar to what happens in AD, studies such as Reis et al. [31] found a difference in amyloid and tau levels in AD patients compared to MDD, suggesting a different role of amyloid metabolism in depression, compared with dementia. This evidence concerns the gene MAPT and Alzheimer disease.