Decline in IQ linked to frequent or dependent use of cannabis use in youth

4 hours ago

Cannabis is the most frequently used illicit substance globally, with the highest prevalence among young people.
Adolescent cannabis use is linked to poorer mental health outcomes, increased risk of mood disorders, self-harm, and suicidality.
Frequent or dependent cannabis use in youth is associated with a small but significant decline in IQ, particularly in verbal IQ.
There is strong evidence associating cannabis use with psychotic disorders, especially with high-potency cannabis.
Cannabis use correlates with negative psychosocial outcomes, such as lower educational attainment and employment prospects.
Early initiation and frequent use in adolescence are risk factors for later cannabis dependency, which often persists into mid-life.
The legalization of cannabis and reduced perception of harm may increase use among vulnerable populations, worsening public mental health.
The developing brain is particularly susceptible to harm from cannabis during youth, with potential long-term effects on intelligence and brain structure.
This meta-analysis found an average decline of about 2 IQ points in frequent or dependent cannabis users, though the clinical significance is modest.
Limitations include potential residual effects of cannabis, heterogeneity in study methods, and short follow-up periods in most studies.

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