Reduced serotonin receptors and transporters in normal aging adults: a meta-analysis of PET and SPECT imaging studies.

Alterations in serotonin (5-HT) function have been hypothesized to underlie a range of physiological, emotional, and cognitive changes in older age. Here, we conducted a quantitative synthesis and comparison of the effects of age on 5-HT receptors and transporters from cross-sectional positron emission tomography and single-photon emission computed tomography imaging studies. Random-effects meta-analyses of 31 studies including 1087 healthy adults yielded large negative effects of age in 5-HT-2A receptors (largest in global cortex), moderate negative effects of age in 5-HT transporters (largest in thalamus), and small negative effects of age in 5-HT-1A receptors (largest in parietal cortex).