There are conflicting results regarding regional age-related changes in serotonin terminal density in human brain. Some imaging studies suggest age-related declines in serotoninergic terminals and perikarya. Other human imaging studies and post-mortem biochemical studies suggest stable brain regional serotoninergic terminal densities across the adult lifespan. In this cross-sectional study, we used [11C]3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile positron emission tomography to quantify brain regional serotonin transporter density in 46 normal subjects, ranging from 25 to 84 years of age. Both voxel-based analyses, using sex as a covariate, and volume-of-interest-based analyses were performed. Both analyses revealed age-related declines in [11C]3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile binding in numerous brain regions, including several neocortical regions, striatum, amygdala, thalamus, dorsal raphe, and other subcortical regions. Similar to some other neurotransmitter systems of subcortical origin, we found evidence of age-related declines in regional serotonin terminal density in both cortical and subcortical regions.
Keywords: Raphe; Serotonin; Serotonin transporter.