Does smoking a joint make you feel a little bit lazy? According to new research, when your “Reefer Madness” turns into “Reefer Can’t-get-off-the-couch,” it could be because the cannabis is suppressing your ability to synthesize dopamine–the neurotransmitter associated with the pleasure of eating chocolate, and increasingly, motivation.
In an effort to study the (controversial) link between cannabis use and psychosis, researchers from three London universities examined the brains of pot smokers for differences in dopamine levels, since abnormal dopamine activity is associated with psychotic symptoms, especially schizophrenia. Their work is published online in Biological Psychiatry.
Using PET scans, the study looked at the brains of 19 regular cannabis users who had started smoking pot as teens, and had experienced psychosis-like behaviors under the influence of the drug–including perceptual distortion and paranoid ideas like “people can put thoughts into your mind” and “you can sense an evil presence around you, even though you cannot see it.” The control group had used cannabis fewer than 10 times in their life, and hadn’t used it at all in the three months prior to the study.
Though the researchers hypothesized that habitual pot users would experience increased dopamine production, since that has been linked with psychosis, they found that regular (at least weekly) cannabis users actually had a reduced capacity to synthesize dopamine. A causal relationship couldn’t be proven, but those who started smoking earlier or smoked more had the lowest dopamine levels. The frequency of psychosis-like symptoms didn’t have an effect on dopamine.
“Our ﬁndings of reduced dopamine synthesis capacity in dependent subjects may reﬂect a ‘blunted’ dopamine system,” the authors write.
This lack of dopamine could possibly be the underlying reason as to why marijuana doesn’t exactly turn people into go-getters, the authors suggest: Without the drive of dopamine, apathy reigns.