Transcriptomic Stage-Specific Architecture of Opioid Exposure Versus Dependence Progression: TWAS Insights, Mechanisms, and Translational Implications

Opioid exposure and opioid dependence are related but not identical clinical and genetic states. Prior work from the Psychiatric Genomics Consortium showed that liability to opioid use and liability to opioid dependence depend strongly on how control groups are defined [1], suggesting that exposure and progression may have partly distinct biological architectures. Here, we used a stage-aware, multi-gene-set transcriptome-wide association framework to examine three contrasts from the Polimanti et al. opioid GWAS: opioid-exposed versus unexposed controls, opioid dependence versus exposed non-dependent controls, and opioid dependence versus unexposed controls. Six biologically motivated gene sets were selected to capture direct opioid signaling, broad neuroactive receptor biology, codeine and morphine metabolism, DREAM-related transcriptional regulation, pain response, and alkaloid response.The strongest pattern was not a simple increase in signal from exposure to dependence. Instead, exposure and dependence showed partly opposing transcriptomic profiles. In the neuroactive ligand-receptor gene set, the exposure contrast and the dependence-among-exposed contrast were strongly anti-correlated, while the two dependence contrasts were positively correlated. Dependence-stage signals converged on OPRK1, DREAM-pathway genes, cAMP/PKA/calcium signaling components, glutamatergic receptors, and a marked GCH1 sign-flip in the pain-response set. These findings support a staged model in which opioid exposure is enriched for drug-response, pain-indication, serotonergic, and pharmacokinetic signals, whereas dependence progression is more closely linked to KOR/dynorphin negative affect, intracellular adaptation, glutamatergic remodeling, and pain sensitization. The leading follow-up targets are OPRK1, GCH1, ADCY6/ADCY9, PDE4B/PDE1B, PRKAR2A/PRKAR2B, PPP3R1/PPP3CC, PLCB3, GRM2/GRM3, and HTR1B.