A study published in Frontiers in Psychiatry used brain imaging to examine dopamine receptor D2 availability in cannabis-dependent users after recovery from cannabis-induced psychosis.
The participants included eight ex-cannabis-dependent users who stopped using cannabis. Participants also included those who underwent a four-month treatment for cannabis-induced psychosis with anti-psychotic medication and psychosocial support in an inpatient drug treatment center. They were compared with nine ex-MDMA "ecstasy" abusers who abstained from substance use after receiving a four-month-long medication and psychosocial treatment at the same treatment facility.
This dopamine neurotransmission study compared dopamine receptor D2 availability in the striatum of recently abstinent cannabis-dependent individuals who had recovered from psychosis with abstinent MDMA (ecstasy users and healthy controls). The study found no significant difference in dopamine D2 receptor availability in the caudate between cannabis users recovering from psychosis, MDMA users, and healthy controls. However, there was some evidence of reduced D2 receptor availability in the right putamen.
Cannabis-abstinent users who were treated for cannabis-induced psychotic episodes showed no difference in dopamine D2 receptor availability in the caudate (a subcortical structure involved in visual information processing and motor control) compared with abstinent MDMA "ecstasy" abusers and healthy control participants. The study suggests that cannabis-induced psychosis has a minimal effect on dopamine reward mechanisms. The study also provided evidence for reduced D2 receptor availability measures in the right putamen (a brain structure involved in learning and motor control). This finding may indicate a residual effect of pharmacological medication. The findings suggest there is no association between remission of cannabis-induced psychosis and hyper-dopaminergic activity.
Increasing concern over the association between cannabis use disorder and psychosis has prompted policymakers to enforce stricter regulations on access and use. Research on recovery from cannabis-induced psychosis and its effects on the brain's dopamine neurotransmission is critical for effective cannabis policy development.
Sources: Frontiers in Psychiatry, Psychiatric Times