MDD individuals showed about a 26% decline in serotonin 1A receptor (5-HT1AR) in the mesiotemporal cortex [60], and significantly reduced postsynaptic binding of 5-HT1AR in the left lateral orbitofrontal cortex, medial temporal cortex, and subgenual ACC has also been observed in PPD [61], indicating another similarity that major depression shares with its subtype. This evidence concerns the gene HTR1A and major depressive disorder.