HTR1A and Alzheimer disease: Decreased 5‐HT1A receptor binding in neocortical and limbic regions, such as the hippocampus and amygdala, has been reported in several postmortem studies in AD and interpreted as a consequence of pyramidal neuron loss (Bowen et al., 1983, 1989; Cross et al., 1984; Crow et al., 1984; Lai et al., 2011; Mizukami et al., 2011; Vidal et al., 2016).