HTR2A and major depressive disorder: The normal expression of serotonin 5-HT2A in cortical neurons, in seven out of eight brains studied, may tentatively support the theory of researchers at the Baker Heart Re-search Institute in Melbourne (Australia) and the researchers at Wayne State University (USA), who maintain that depression or panic disorder (panic anxiety) can go hand in hand with an increase rather than a decrease in serotonin levels [32].