Prefrontal-Habenular Microstructural Impairments in Human Cocaine and Heroin Addiction

The habenula (Hb) is central to adaptive reward and aversion-driven behaviors, comprising a hub for higher-order processing networks involving the prefrontal cortex (PFC). Despite an established role in preclinical models of cocaine addiction, the translational significance of the Hb, and its connectivity with the PFC, in humans is unclear. Using diffusion tractography, we detailed PFC structural connectivity with the Hb and two control regions, quantifying tract-specific microstructural features in healthy and cocaine-addicted individuals. White matter was uniquely impaired in PFC-Hb projections, driven by short-term abstainers but also identified in current cocaine users. Abnormalities in this tract further generalized to an independent sample of heroin-addicted individuals and were associated with earlier onset of drug use across the three addiction subgroups, potentially serving as a predisposing marker amenable to early intervention. Importantly, these findings contextualize a plausible PFC-Hb circuit in the human brain, supporting preclinical evidence for its impairment in cocaine addiction.