Men with a lifetime history of cannabis use experience “significantly less cognitive decline” over their lifetimes compared to non-users, according to new research.
The study, published by a team of Danish researchers in the journal Brain and Behaviour, assessed the relationship between cannabis use and age-related cognitive decline in a cohort of 5,162 men.
Participants’ IQs were evaluated in early adulthood, with a mean age of 22, and again in late midlife, at an average age of 62.
Researchers found that participants with a history of cannabis use experienced “significantly less cognitive decline” over their lifetimes than non-users.
“In this study of 5162 Danish men, the mean cognitive decline was found to be 6.2 IQ points over an average of 44 years. Notably, cannabis users exhibited statistically significantly less cognitive decline compared to nonusers … and the association remained significant when controlling for potential confounders. … In the fully adjusted model, cannabis use was associated with 1.3 IQ points less cognitive decline than the decline observed in the reference group,” researchers said.
Neither age of initiation nor frequency of use was associated with negative effects on cognition among cannabis consumers. Over half (51.1%) of the cannabis users began consuming before the age of 18, 43.5% beginning between the ages of 18 and 25, and 5.4% after the age of 25.
“[The findings] align with most existing studies, suggesting no association between cannabis use and greater cognitive decline… Among cannabis users, no significant associations with age-related cognitive decline could be demonstrated for age of initiation of cannabis use. Years of frequent cannabis use were generally associated with no significant difference in cognitive decline when compared with no frequent use… Further studies are needed to investigate whether these findings reflect that there are no adverse effects on cognitive decline or that the effects of cannabis are temporary and disappear after a prolonged period of time.”
The findings align with other studies that show cannabis may be linked to improved cognitive outcomes in later life. A 2023 study, involving 297 participants aged between 50 and 84, all of whom were living with HIV, found an improvement in cognitive performance in older adults who occasionally consumed cannabis compared to those who didn’t. A 2024 study found that elderly mice treated with long-term, low doses of cannabis showed improvements in brain function.
“This study contributes to the sparse knowledge on this subject and aligns with most existing studies, suggesting no association between cannabis use and greater cognitive decline.
“More specifically, in the present study, cannabis users experienced slightly less cognitive decline compared to nonusers, and the association remained significant when controlling for potential confounders. Among cannabis users, no significant association was found with cognitive decline for either age of initiation of cannabis use or frequent cannabis use,” said the authors of the Danish study.
“Further studies are needed to investigate whether these findings reflect that there are no adverse effects on cognitive decline or that the effects of cannabis are temporary and disappear after a prolonged period of time.”
