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Study finds signs of brain changes in pot smokers

By Associated Press

LAST UPDATED: 06:57 p.m. HST, Apr 15, 2014

Marijuana is displayed during the grand opening of the Seattle location of the Northwest Cannabis Market, for sales of medical marijuana products, Wednesday, Feb. 13, 2013. The market hosts nine permanent vendors for seven-day-a-week sales, as well as daily vendors of a variety dried medicines, edible products and starts. Voters in Washington state last fall passed Initiative 502, which legalizes the recreational possession of up to an ounce of marijuana and calls for the creation of state-licensed pot growers, processors and retail stores. Recreational marijuana sales are expected to begin late this year, and in the meantime, the state's medical marijuana industry continues to operate. (AP Photo/Elaine Thompson)

NEW YORK » A small study of casual marijuana smokers has turned up evidence of changes in the brain, a possible sign of trouble ahead, researchers say.

The young adults who volunteered for the study were not dependent on pot, nor did they show any marijuana-related problems.

"What we think we are seeing here is a very early indication of what becomes a problem later on with prolonged use," things like lack of focus and impaired judgment, said Dr. Hans Breiter, a study author.

Longer-term studies will be needed to see if such brain changes cause any symptoms over time, said Breiter, of the Northwestern University Feinberg School of Medicine and Massachusetts General Hospital.

Previous studies have shown mixed results in looking for brain changes from marijuana use, perhaps because of differences in the techniques used, he and others noted in Wednesday's issue of the Journal of Neurosciences.

The study is among the first to focus on possible brain effects in recreational pot smokers, said Dr. Nora Volkow, director of the National Institute on Drug Abuse. The federal agency helped pay for the work. She called the work important but preliminary.

The 20 pot users in the study, ages 18 to 25, said they smoked marijuana an average of about four days a week, for an average total of about 11 joints. Half of them smoked fewer than six joints a week. Researchers scanned their brains and compared the results to those of 20 non-users who were matched for age, sex and other traits.

The results showed differences in two brain areas associated with emotion and motivation — the amygdala and the nucleus accumbens. Users showed higher density than non-users, as well as differences in shape of those areas. Both differences were more pronounced in those who reported smoking more marijuana.

Volkow said larger studies are needed to explore whether casual to moderate marijuana use really does cause anatomical brain changes, and if so, whether that leads to any impairment.

The current work doesn't determine whether casual to moderate marijuana use is harmful to the brain, she said.

Murat Yucel of Monash University in Australia, who has studied the brains of marijuana users but didn't participate in the new study, said in an email that the new results suggest "the effects of marijuana can occur much earlier than previously thought." Some of the effect may depend on a person's age when marijuana use starts, he said.

Another brain researcher, Krista Lisdahl of the University of Wisconsin-Milwaukee, said her own work has found similar results. "I think the clear message is we see brain alterations before you develop dependence," she said.

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Jerry_D wrote:
Oh yes...I don't doubt that smoking weed causes a loss of motivation. But why is that a bad thing? Oh, I get it...I think I know why: In today's world where MOTIVATION leads to PRODUCTIVITY, which in turn leads to ECONOMIC GROWTH and an increase in GDP and GNP (and, on an individual level, motivation leads to HIGHER PAYING JOBS which in turn means more INDIVIDUAL TAXES paid to the government)....yes, I can see how our governments would not want the people to smoke weed and maybe SLOW DOWN, RELAX, and ENJOY life a bit more rather than continue to compete against each other in this RAT RACE.
on April 15,2014 | 03:09PM
hawaiikone wrote:
Chill Jerry, take another hit, my friend...
on April 15,2014 | 03:32PM
Jerry_D wrote:
Stop camping and pass it this way, brother!
on April 15,2014 | 03:40PM
OldDiver wrote:
You could replace the word weed with many current legal drugs. From alcohol, sleeping pills, prolonged use of antihistamines, anti depressents, drugs to treat psychotic conditions and so on.
on April 15,2014 | 09:28PM
PCWarrior wrote:
A federal study to back the federal viewpoint of marijuana. Don't be surprised at what they tell you. Reefer Madness lives!
on April 16,2014 | 09:46AM
onoahu wrote:
As long as I'm not the one paying to subsidize you when you "SLOW DOWN, RELAX, and ENJOY life" it's fine by me. However I suspect that the weed smoking % is higher for EBT card users.
on April 16,2014 | 08:46AM
NiteMarcher wrote:
They need to take a good look at the meth problems we have going on throughout the nation--never mind looking at nature's weed which was created naturally. The brain goes through enormous changes along with the physical body and appearance of the meth user. These are the guys ripping off everything and anything they can get there hands on, even if it means bringing down their entire family.
on April 15,2014 | 04:52PM
onevoice82 wrote:
Agree NiteMarcher and also; I think the study missed an important fact.....the users brains were impaired to begin with! Why else would people want to escape life with all it's challenges and hardships.
on April 16,2014 | 05:15AM
Slow wrote:
20 individuals is not a valid survey. And yes, meth is worse than marijuana, though that is not the topic. Being a smoker, I hope further research is done. However, defending marijuana because it is "created naturally" has always seemed to be either irrelevant or a silly distraction. Cobra venom, ebola virus, Portugese man-o-war, hurricanes, toxic mushrooms are all "created naturally." Nature is not good nor evil.
on April 16,2014 | 07:06AM
sailfish1 wrote:
Then again, maybe people with these brain differences are more prone to smoke marijuana - i.e. people who are not so smart get into drugs more so than intelligent people.
on April 15,2014 | 06:33PM
Slow wrote:
Intoxicants are, at best, unnecessary and at worst, lead to death. But nowhere has it ever been suggested, much less proven, that users are dumber than sober folks. You ever have beer or a toke? Ever? Are you smarter than your neighbor?
on April 16,2014 | 07:10AM
kolohepalu wrote:
Dr. Breiter oversteps in his assessment of his findings. He may (or may not) have seen changes in certain areas of the brain. Whether what he saw makes any difference in people's judgement or motivation remains to be seen- but it's doubtful. There are tons of people running around who have smoked daily for years- they don't stick out like sore thumbs for their lack of judgement or motivation- in fact, many are doctors, lawyers, judges, cops, etc.
on April 15,2014 | 07:02PM
BlueDolphin53 wrote:
The issue isn't that they couldn't become productive members of society. Of course they can. The issue is whether or not the damage prevents them from reaching their potential.
on April 15,2014 | 07:43PM
kolohepalu wrote:
Doctors, lawyers, judges. . .
on April 16,2014 | 06:16AM
TTPwr wrote:
on April 16,2014 | 07:47AM
BIG wrote:
on April 16,2014 | 08:32AM
kolohepalu wrote:
NOTE: study sponsored by National Institute on Drug Abuse. I wonder how much funding they would lose if marijuana were deemed relatively harmless- THAT wouldn't be any motivation, would it??
on April 15,2014 | 07:06PM
WalkoffBalk wrote:
on April 15,2014 | 09:14PM
dyw001 wrote:
Actually the increase in size of the amygdala and the nucleus accumbens may be a good thing. According to a recent study, marijuana use can delay or stop dementia or alzheimer's. "A prominent professor of neuroscience, immunology and medical genetics at Ohio State University says in an recent interview that using low doses of marijuana for prolonged periods of time at some point in your life “is probably going to slow the onset or development of dementia, to the point where you’ll most likely die of old age before you get Alzheimer’s.”
on April 16,2014 | 06:55AM
lokela wrote:
Getting hungry.
on April 16,2014 | 06:57AM
Lanikaula wrote:
have some brownies...
on April 16,2014 | 07:29AM
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