Abstract
Alcohol use disorder (AUD) induces complex transcriptional and regulatory changes across multiple brain regions including the caudate nucleus, which remains understudied. Using paired single-nucleus RNA-seq and ATAC-seq on caudate samples from 143 human postmortem brains, including 74 with AUD, we identified 17 distinct cell types. A significant portion of the alcohol-related differences in gene expression were accompanied by a corresponding difference in chromatin accessibility within the gene. We observed transcriptional differences in medium spiny neurons that impact RNA metabolism and immune response pathways. A small cluster of D1/D2 hybrid neurons showed AUD-induced differences distinct from the D1 and D2 types, suggesting a unique role in AUD. Those with AUD had a higher proportion of microglia in an inflammatory state; astrocytes entered a reactive state partially regulated by JUND. Oligodendrocyte dysregulation was driven in part by OLIG2 activity and increased TGF-β1 signaling from microglia and astrocytes. We also observed increased microglia-astrocyte communication via the IL-1β pathway. These findings provide valuable insights into the genetic and cellular mechanisms in the caudate related to AUD. They also demonstrate the broader utility of large-scale multiomic studies in uncovering complex gene regulation across diverse cell types, which has implications beyond the substance use field.