A GWAS-Derived Polygenic Score for Interleukin-1β is Associated with Hippocampal Volume in Two Samples

Accumulating research suggests that the pro-inflammatory cytokine interleukin-1{beta} (IL-1{beta}) has a modulatory effect on the hippocampus, a brain structure important for learning and memory as well as linked with both psychiatric and neurodegenerative disorders. Here, we use an imaging genetics strategy to test an association between an IL-1{beta} polygenic score, derived from summary statistics of a recent genome-wide association study (GWAS) of circulating cytokines, and hippocampal volume, in two independent samples. In the first sample of 512 non-Hispanic Caucasian university students (274 women, mean age 19.78 {+/-} 1.24 years) from the Duke Neurogenetics Study, we identified a significant positive correlation between higher polygenic scores, which presumably reflect higher circulating IL-1{beta} levels, and average hippocampal volume. This positive association was successfully replicated in a second sample of 7,960 white British volunteers (4,158 women, mean age 62.63{+/-}7.45 years) from the UK Biobank. Collectively, our results suggest that a functional GWAS-derived score of IL-1{beta} blood circulating levels affects hippocampal volume, and lend further support in humans, to the link between IL-1{beta} and the structure of the hippocampus.