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.