Researchers have studied the association between illegal drug use and cognitive function in middle adulthood. They have seen that “at the population level, it seems that the current use of illegal drugs is associated with impaired cognitive functioning in early middle age.”
A total of 8,992 participants were interviewed at 42 years old in 1999 and 2000. The authors analyzed data from three cognitive tests when the participants were 50 years old in 2008 and 2009.
Cannabis was by far the most common drug among participants (six percent said they had consumed in the past year), while a quarter said they had never used. Overall, the study found that there was no evidence that current or past drug consumers they had poorer mental function. In fact, when current and past users were analyzed together, the test results tended to be older.
But that advantage was small, the researchers said, and could only reflect another finding: that people who had never used drugs generally had a higher educational level than nonusers. “However, the authors cannot exclude the possibility that some individuals or groups, such as those with a larger or prolonged use, may be harmed,” they write in their article for the American Journal of Epidemiology.