A study of about 1,000 New Zealanders has concluded that individuals who began smoking marijuana before age 18, and then smoked it for years, experienced a drop in IQ — a drop that persisted even if the individual quit.
This is one of those studies that draws awfully broad conclusions, and is a bit disturbing, besides. The researchers began assessing the study participants, a group from Dunedin, New Zealand, when they were children, before they started smoking, and then interviewed them regularly about their pot-smoking habits, and other activities, for more than 20 years. The researchers took the resulting data and sought to screen for other factors, including use of alcohol and other drugs, as well as education levels. They concluded that persistent marijuana smokers — defined as someone who smoked at least four times a week, year after year, into their 20s and 30s — experienced noticeable drops in IQ, with the amount of marijuana consumption correlating to the amount of IQ loss. The study found that persistent marijuana use over 20 years is associated with neuropsychological decline and that the drug may have neurotoxic effects in adolescents.
There’s no real surprise in these conclusions. Many of us know people who never moved past the heavy stoner lifestyle and ended up sapped of energy and ambition, not doing much of anything with their lives except listening to Dark Side of the Moon and complaining about their latest bad break. If you go to any college town, you’ll likely see some of them, scraping by somehow.
What’s disturbing about the study is that the scientists seem to have treated real people like lab rats, testing and interviewing and assessing them as they continued a habit that apparently was producing irrevocable mental decline. There’s no indication in the article linked above that researchers did anything to try to convince participants to stop their use — even in the case of adolescents. What are the ethical obligations of researchers under such circumstances? When should a scientist stop being a neutral observer and recorder of clinical facts, and start being a person who tries to help a kid avoid a permanent downward spiral?