Adults who consumed cannabis for a year did not show any reduction in working memory, reward, and inhibitory control brain function, a study has shown.
The federally funded research, published by the American Medical Association in the journal JAMA Network Open, involved 57 patients who had been newly prescribed medical cannabis. Patients were observed using functional magnetic resonance imaging (fMRI) at the start of their medical cannabis use and after 12 months. At the same time, similar data were also collected for non-medical cannabis patients to use as a control group. The study was conducted from July 2017 to July 2020 among participants from the greater Boston area who were recruited as part of a clinical trial of individuals seeking medical cannabis cards for anxiety, depression, pain, or insomnia symptoms.
“After year-long cannabis use for medical symptoms in adults… we did not observe functional differences between baseline and brain activation at 1 year during working memory, reward processing, or inhibitory control tasks, nor an association between changes in cannabis use frequency and brain activation at 1 year,” researchers reported. “Similarly, few significant changes in behavioral performance emerged. This suggests that cannabis use for medical purposes, within the snapshot of cognition captured by these tasks and within a mostly older, White, female, and generally well-educated population, did not have a significant association with brain activation or cognitive performance.”
“Our results suggest that adults who use cannabis, generally with light to moderate use patterns, for symptoms of pain, anxiety, depression, or poor sleep, experience few significant long-term neural associations in these areas of cognition,” researchers said.
The research was conducted by a team affiliated with Harvard Medical School and the McGovern Institute for Brain Research at the Massachusetts Institute of Technology. In the published paper, the authors state that previous research linking cannabis use with reduced cognitive function compares cannabis consumers with non-cannabis consumers, and does not track changes in cognitive performance before and after use. “[M]ost of the evidence for brain changes with cannabis use is derived from between-group brain differences between those who use cannabis and those who do not, rather than from longitudinal changes at pre– and post–cannabis use time points, raising the question of whether preexisting differences between those who use cannabis and those who do not underlie observed changes.”
“Our results suggest that adults who use cannabis, generally with light to moderate use patterns, for symptoms of pain, anxiety, depression, or poor sleep, experience few significant long-term neural associations in these areas of cognition,” said the study, which was funded by the National Institute on Drug Abuse (NIDA).
