Summary: A study spanning 44 years and involving over 5,000 men challenges long-held beliefs about cannabis and cognition. Researchers found that cannabis users experienced slightly less cognitive decline from early adulthood to late midlife compared to nonusers.
Neither the age of cannabis initiation nor the frequency of use showed a significant impact on cognitive decline. These findings suggest that long-term cannabis use might not impair—and could even modestly benefit—cognitive aging, although further research is needed to confirm the results.
Key Facts:
- Cognitive Decline: Cannabis users experienced 1.3 IQ points less decline over 44 years compared to nonusers.
- Initiation Age: Starting cannabis before age 18 had no significant effect on long-term cognitive decline.
- Frequency of Use: Regular cannabis use (≥2 times per week) was not associated with greater cognitive decline.
Source: Neuroscience News
Cannabis, often maligned for its short-term cognitive effects, may not have the long-term impact on mental sharpness once thought.
A groundbreaking Danish study tracking over 5,000 men for 44 years found that cannabis users experienced slightly less cognitive decline from early adulthood to late midlife compared to nonusers.
Despite cannabis being a Schedule I drug with a reputation for harm, this research suggests its effects on aging brains might be more nuanced.
The study examined cognitive changes using intelligence test scores taken in early adulthood and again decades later.
Video credit: Neuroscience News
Cannabis users showed a modest advantage in maintaining IQ levels over time, even when controlling for lifestyle factors such as education and substance use.
Moreover, neither the age at which cannabis use began nor frequent use significantly accelerated cognitive decline.
These findings challenge previous assumptions that cannabis usage contributes to steeper cognitive decline.
Instead, they hint at a complex relationship where factors like baseline IQ, education, and lifestyle may play a larger role.
While the observed differences were minor and might lack clinical significance, the research opens the door for further exploration of cannabis’ long-term effects on cognition.
Funding: This work was supported by a number of grants. The DanACo cohort was established by pooling the two follow-up studies, the LiKO-15 and DiaKO-19 studies.
The establishment of the LiKO-15 study was part of the Phenotypes in Alcohol Use Disorders project, which was supported by Innovation Fund Denmark, Health and Clinical Research (Grant Number 603-00520B) and was further supported by the Center for Healthy Aging, University of Copenhagen, and a PhD scholarship grant to MG from the Faculty of Health and Medical Sciences, University of Copenhagen.
The establishment of the DiaKO-19 cohort was supported by grants from Independent Research Fund Denmark (Grant Number: 8020-00094B), Svend Andersen foundation, and Doctor Sofus Carl Emil Friis and wife Olga Doris Friis’s foundation.
Further support for ongoing research using the LiKO-15 and DiaKO-19 cohorts has been granted by the Lundbeck foundation (Grant Number: R380-2021-1433), Helsefonden (Grant Number: 22-B-0196), and by the internal research funds of Bispebjerg and Frederiksberg hospitals.
The funding bodies had no role in the design of the studies, nor in the collection, analysis, and interpretation of data and writing of the manuscript.
About this cognition and cannabis research news
Author: Neuroscience News Communications
Source: Neuroscience News
Contact: Neuroscience News Communications – Neuroscience News
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Cannabis Use and Age-Related Changes in Cognitive Function From Early Adulthood to Late Midlife in 5162 Danish Men” by Kirstine Maarup Høeg et al. Brain and Behavior
Abstract
Cannabis Use and Age-Related Changes in Cognitive Function From Early Adulthood to Late Midlife in 5162 Danish Men
Introduction
Cannabis is by far the most widely used and abused drug listed on the Drug Enforcement Administration’s Schedule I, which includes drugs with a high potential for abuse. There is evidence of short-term negative effects of cannabis use on cognition, but only a limited number of studies have explored the association between cannabis use and age-related cognitive decline. The aim of the present study was to investigate the relationship between cannabis use and age-related cognitive decline from early adulthood to late midlife.
Methods
The study population consisted of 5162 men who had participated in Danish follow-up studies on cognitive aging. These studies included scores on the military intelligence test Børge Prien’s Prøve from both the conscription assessment (mean age = 20 years; p1 and p99: 18 and 26 years) and from the follow-up (mean age = 64 years; p1 and p99: 55 and 72 years) as well as extensive data on lifestyle and health from the follow-up questionnaires. The association between cannabis use and age-related cognitive decline was investigated in linear regression models.
Results
Men with a history of cannabis use had less cognitive decline from early adulthood to late midlife compared to men without a history of cannabis use. Among cannabis users, neither age of initiation of cannabis use nor frequent use was significantly associated with a greater age-related cognitive decline.
Discussion and Conclusions
In a sample of more than 5000 men followed for a mean of 44 years, we found no significant harmful effects of cannabis use on age-related cognitive decline.
