Even smoking the occasional joint as a teenager can cause poor cognitive functioning, a new study has found.
The study that was conducted by the University of Colorado’s School of Medicine compared teenage siblings to determine the impact that early and frequent dagga use has on cognitive functioning.
They found that even moderate dagga use may have adverse effects that couldn’t be explained by other factors, such as peer group influence, parental behaviour and socio-economic status.
"We wanted to expand our understanding of whether cannabis use is related to lower cognitive functioning," said Jarrod M. Ellingson, an assistant professor of psychiatry at the University of Colorado’s School of Medicine, in a statement.
"There's a large body of evidence that cannabis use is linked to cognitive functioning, but we know that cannabis use is not isolated from other important risk factors. That was the primary motivation behind this study, in which we compared siblings to account for many of these risk factors."
The study was published in the journal Addiction. Through the study, Ellingson and his colleagues were able to establish that different levels of cannabis use related to poorer cognitive functioning, in particular verbal memory.
The study involved 1,192 adolescents from 596 families. The majority were male. Drug use was assessed through clinical interviews and cognitive abilities were assessed through a battery of neuropsychological tests.
"More work needs to be done to determine how cannabis use is related to cognitive functioning and we hope that our study can help inform future study designs," Ellingson said. "These studies are particularly important because cannabis is becoming more potent and more accessible as states legalise its recreational use."
Ellingson added that:"Due to changes in the legality of recreational and medical cannabis and widespread access in many (US) states, valid empirical data must be available to inform policy and public health decisions, including how cannabis use may affect the developing brain."