Background. We reported previously that the socio-economic status (SES) of individuals predicts variation in brain serotonergic responsivity, as assessed by neuropharmacological challenge in an adult community sample, and that this association is qualified by allelic variation in the serotonin transporter gene-linked polymorphic region (5-HTTLPR). Here we examine whether serotonergic responsivity covaries similarly with the SES of communities, as indexed by US Census data in the same study sample.

Method. Community SES was defined by levels of income, economic disadvantage, housing costs, and educational attainment of census tracts in which 249 locally recruited study participants (54% male) resided. Serotonergic responsivity was assessed as the baseline-adjusted, peak plasma prolactin (Prl) concentration following acute administration of the serotonin-releasing agent, fenfluramine; tissue for DNA extraction and 5-HTTLPR genotyping was available on 131 participants.

Results. Subjects residing in census tracts of lower SES showed a blunted Prl response to fenfluramine (diminished serotonergic responsivity) relative to individuals living in more affluent neighborhoods. When adjusted for personal income and education, SES at the community level continued to predict fenfluramine-stimulated Prl responses and did so independently of 5-HTTLPR genotype.

Conclusions. Area-level indices of relative social and economic disadvantage covary with individual differences in brain serotonergic responsivity, and this association is, in part, independent of individually defined SES. These findings may be relevant to reported effects of low community SES on the prevalence of psychiatric disorders or behaviors associated with dysregulation of central serotonergic function, such as depression, impulsive aggression, and suicide.