A new study carried out by British scientists has found further evidence supporting the absence of a connection between mental decline in later life from previous drug use.
I’m not too surprised to be honest… Cannabis was shown to be the most commonly used illicit drug by the 9000 participants in this study. People were surveyed at 42 years of age and then had their cognitive abilities tested 8 years later at age 50. 12 illicit drugs were included in the study comprising substances like cocaine, LSD, psilocybin mushrooms, amphetamines and ecstasy.
The authors of the study state these findings and implications in the abstract that:
At the population level, it does not appear that current illicit drug use is associated with impaired cognitive functioning in early middle age. However, the authors cannot exclude the possibility that some individuals and groups, such as those with heavier or more prolonged use, could be harmed.
However, the authors cannot exclude the possibility that some individuals and groups, such as those with heavier or more prolonged use, could be harmed.
Although, aforementioned substances such as cannabis and cocaine have short term effects on ones cognitive abilities if used periodically, this study is further evidence for ones mental capacities returning to normal soon after use has stopped.
That said, it would be best to look at longer studies from earlier ages to really clarify things. As raised in one of the below comments by Ian, why would you expect to see a difference between the ages of 42 and 50. More interesting would be examining different degrees of usage of these drugs in much younger people, from their teens, through their adult life in order to examine long term effects of drug usage of cognitive abilities. Use at a younger age is probably much more detrimental to the mind, when it is still developing, than say at at 42 when it has long since matured.
More info here
Assuming you’ve paraphrased this study correctly (sorry, I haven’t gone to read the original), I can’t see they can make any claim at all regarding apparent impairment “later in life” if all they were comparing was matched samples at age 42 and 50. Leaving alone the “later in lfe” at 50 issue, why would anyone expect previous drug use (or any other behaviour) to change cognitive function between 42 and 50? I HATE these pseudo-scientific medical studies that sound plausible but the methodology too often makes it impossible to sensibly answer the question. Lack of a difference does not imply lack of causality or even correlation if there would be no expectation of a difference in the first place.
I guess the point of the study was to see if any form drug use had long term effects on cognition later in life after the mind had finished maturing. Many of the people had used substances periodically throughout those 8 years, from high usage to none at all and the point was that when it came to cognition there was no difference found. But yes, I think a study of greater time span, specifically including teenages and then following their cognitive abilities as they get older and the effects of substances on them should be done.
Thanks Pete, for these interesting and thought provoking postings.
The phrase that caught my eye though was “At the population level.” I think we can all agree that the results may vary from individual to individual and depend on how extensive their drug use was.