A cohort study by American scientists involving 250 children, 80 of whom were exposed prenatally (during their mother's pregnancy) to cannabis, found that it was associated with impairments in attention, inhibitory control, and planning abilities. Furthermore, as reported in JAMA Pediatrics, these children showed increased aggression at age five.
According to researchers led by Sarah Keim of the Research Institute at Nationwide Children's Hospital, the maternal cohort also had high rates of tobacco, other substance use, and alcohol use during pregnancy. Most families in the cohort lived in poverty. Age-adjusted standardized measures of attention and inhibitory control were approximately 0.4 standard deviations lower among those who used cannabis.
