Data from the “Dunedin Study” has shown that under-18s who regularly smoke marijuana are at risk of permanently reducing their IQ. The same dip doesn’t occur in those who become frequent users after 18, supporting previous research which has suggested that marijuana is particularly harmful for the developing brain.
Those dependent on marijuana from a young age saw an average decline of eight IQ points between the ages of 13 and 38, the two ages at which IQ was tested in the University of Otago’s ongoing longitudinal study, which followed a group of 1,037 children from birth between 1972 and 1973.
The people defined as dependent on cannabis during youth were those who smoked pot more than once a week before the age of 18, and this accounted for approximately 5% of the study group. Giving up the habit did not reverse the effects.
Dr Simon Adamson of the Otago University National Addiction Centre emphasised that “the results… suggest adult onset regular cannabis use does not lead to cognitive decline,” and that this should inform policy makers. Critic speculates he is referring to the idea of legalisation with an age restriction of 18, something many lobbyists are calling for following the findings. Importantly, the study was able to account for IQs which were low before cannabis dependency occurred. The study also showed that the decline was not simply related to cannabis users being less educated.
Critic proposes that this newsflash explains the “stoner” image, but reminds readers that correlation does not imply causation.
Let them smoke pot!
