A study published in the Journal of Psychopathology and Clinical Science suggests that genetic and environmental factors are more significant factors in adverse mental health effects than moderate cannabis consumption. The study found limited evidence that cannabis consumption leads to the most harmful psychological outcomes, such as paranoia and other psychological disorders.
The research team analyzed data drawn from two longitudinal community twin samples conducted by the Minnesota Center for Twin Family Research and the Colorado Center for Antisocial Drug Dependence. The 4,078 participants were born between 1972 and 1994 and recruited during adolescence. Their cannabis consumption was tracked from ages 11 to 35 between the years 1994 to 2014.
The researchers were mainly interested in measuring “lifetime average cannabis frequency” and determining the cumulative effects of cannabis use throughout adolescence and young adulthood. The study also examined the age of onset and patterns of heavy cannabis consumption.
The methodology featured the co-twin control study design, which involved a quasi-experimental approach to comparing monozygotic twins who share 100% of their genetic makeup. The study design makes use of the natural experiment afforded by twins who differ in their cannabis use and exposure. This approach allows researchers to control for genetic and many shared environmental factors that impact the observed relationships between cannabis use and outcomes.
The researchers analyzed data from self-report surveys and structured clinical interviews to capture data on a wide range of substance use, psychiatric symptoms, and psychosocial factors. Although cannabis use correlated with several adverse outcomes at the individual level, the study showed that these associations decreased when the researchers examined differences between twin pairs. The researchers believe this pattern challenges the notion that many adverse outcomes can be associated with cannabis use and its psychoactive effects. Instead, the study indicates that shared genetic and environmental influences contribute to adverse outcomes.
Sources: Journal of Psychopathology and Clinical Science, PsyPost
