Exposure to marijuana in the womb may increase risk of addiction to opioids later in life, study finds

Prenatal THC exposure is linked to a higher risk of opioid addiction-like behavior later in life, based on a preclinical animal study. Researchers report that fetal exposure to THC rewires the brain reward system, producing dopamine neurons that respond in a hyperactive way and a heightened dopamine release to reward cues such as a light signaling food or an opioid. In animals exposed to THC in utero, motivation to work for opioid drugs increases, and the animals are more likely to relapse when later exposed to opioid-associated environmental cues. The study also includes measurements from tiny brain sensors showing elevated dopamine signaling paired with neurons over-representing opioid-related cues in animals showing strong addiction-like behavior. The work emphasizes potential long-term neurobiological vulnerability from prenatal cannabis exposure and notes sex differences, with the opioid-seeking phenotype occurring more in males than females.