The New York Times (8/28) “Well” blog reports, “People in a study who began smoking marijuana as teenagers and continued to use it heavily for decades lost a few IQ points along the way, while those who started in adulthood did not,” according to research published online in the Proceedings of the National Academy of Science. “The findings, from a study tracking people’s habits from childhood through middle age, suggest that the developing teenage brain is especially vulnerable to drug use, the authors concluded.”
The USA Today (8/28, Winter) “On Deadline” blog reports, “The study, which tracked more than 1,000 New Zealanders from birth to 38, found an average eight-point decline in IQ among “persistent, dependent” users of marijuana younger than 18. About 5% of the study group were considered “marijuana-dependent” — using more than once a week before they were 18 years old, according to the news release (8/28).” What’s more, “quitting did not appear to reverse the effects, and the IQ decline could not be explained by alcohol, other drug use or by having less education, said lead researcher Madeline Meier at Duke University.”
Interestingly, “the researchers didn’t find the same IQ dip for people who became frequent users of pot after 18,” the AP (8/28, Ritter, Perry) reports. “Although experts said the new findings are not definitive, they do fit in with earlier signs that the drug is especially harmful to the developing brain.”
Bloomberg News (8/28, Lopatto) reports, “Because marijuana is the most frequently used illegal drug in the US, looking into how it changes the brain is important, said” Meier. “Daily use among high school seniors is at a 30-year peak, according to a 2011 survey by the National Institute on Drug Abuse.”
HealthDay (8/28, Goodwin) reports, “Though pot has a reputation among many teens for being benign, Meier urged adolescents and their parents to take the findings seriously.”
MedPage Today (8/28, Gever) points out, “The current analysis was supported by the UK Medical Research Council, the US National Institutes of Health, and the Jacobs Foundation.” Also covering the story are WebMD (8/28, Boyles), Medscape (8/28, Harrison), Reuters (8/28, Kelland), and BBC News (8/28, Hughes).
— “Early Marijuana Use Linked to I.Q. Loss, “Benedict Carey, The New York Times, August 27, 2012.