Earlier cannabis initiation among people with recent-onset psychosis is associated with more severe positive symptoms and greater gray matter volume in a cerebellar network previously linked to schizophrenia. This cerebellar volume increase correlates with lower volume in an insula-temporal-frontal network also implicated in schizophrenia. The findings suggest that early cannabis use may alter the developmental trajectory of specific brain networks, increasing later psychosis risk.
Chemsex users—men who have sex with men who use substances like methamphetamine, GHB, mephedrone, or ketamine to enhance sex—show more depression, hypersexuality, and sexual risk behavior than non-users. Their brain activity during a decision-making task revealed reduced N2 responses in fronto-central regions, indicating impaired executive function and inhibitory control. P3 amplitudes did not differ between groups. These deficits may contribute to greater risk of drug abuse and hypersexuality, and understanding them could inform interventions to reduce harm and improve well-being.