US: Cannabis impairs memory, researchers say

Taking cannabis impairs critical thinking and memory function, according to research highlighted by a major scientific review.

Scientists from the National Institute on Drug Abuse (NIDA) in the US looked at studies showing how the drug is linked to addiction, lower IQ, and other adverse health effects.

Dr Nora Volkow, lead author and Director of NIDA, said: “It is important to alert the public that using marijuana in the teen years brings health, social, and academic risk.


“Physicians in particular can play a role in conveying to families that early marijuana use can interfere with crucial social and developmental milestones and can impair cognitive development”.

NIDA warned that as various US states move towards legalising cannabis, use of the drug is likely to increase, as is the number of people “likely to suffer negative health consequences”.

The review, called “Adverse Health Effects of Marijuana Use”, was published in the New England Journal of Medicine and looked at a wide range of scientific data, including research showing that the risk of cannabis addiction increases for daily or young users.


It also highlighted a study from 2012, exposing the link between regular cannabis use in the early teens and lower IQ into adulthood, even if users stopped taking the drug as adults.

The authors noted that cannabis is more potent today than it has been, and so stronger adverse health effects may occur.

In January this year, Colorado became the first US state to legalise cannabis for recreational use.


But two months ago, politicians in Colorado approved two Bills which seek to place tougher restrictions on edible cannabis sales, amid reports of two deaths linked to edible forms of the drug.

A UN drugs watchdog warned that decriminalising cannabis is a “misguided” initiative and risks people’s long-term health.

The International Narcotics Control Board – a body monitoring drug treaties – criticised moves to weaken drug laws around the world in its annual report for 2013.

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