No brain damage found from diffusion tensor imaging

[palmspringsbum]

Consumer Health

Study: Little damage from marijuana
Consumer Health Daily
5/8/2006 5:21:00 PM -0400

NEW YORK, May 8 (UPI) -- In a preliminary study, U.S. researchers failed to find damage to the developing adolescent brain had occurred in those who had used marijuana moderately.

Lynn DeLisi and colleagues from the Nathan S. Kline Institute for Psychiatric Research and New York University School of Medicine used diffusion tensor imaging to scan the brain of 10 young people who had smoked cannabis during adolescence.

The participants were between 17 and 30 years old, and they said they had smoked at least two to three times a week for one or more years during adolescence and had no personal or family history of mental-health problems.

The study subjects were matched for sex, age and social class of parents with 10 controls who had not smoked marijuana regularly as teenagers.

DeLisi and colleagues found no significant differences in brain integrity and brain volume between cannabis smokers and non-smokers, but the study authors warn more research is necessary, both in a larger group of people and to see the effects of heavier use.

The findings are published in Harm Reduction Journal

[palmspringsbum]

Diffusion tensor imaging provides clearer picture of cannabis effect on brain

Medical Studies/Trials
Published: Monday, 8-May-2006
News-Medical.net


Diffusion tensor imaging, a newly developed magnetic resonance imaging technique, could enable researchers to gain a better understanding of the effects of cannabis on the brain.

In a preliminary study published today in the open access journal Harm Reduction Journal, researchers used diffusion tensor imaging to compare the brain tissue of young people who had used cannabis moderately as teenagers and young people who had not. The researchers failed to find any indication that damage to the developing adolescent brain occurred.

Lynn DeLisi and colleagues from the Nathan S. Kline Institute for Psychiatric Research and New York University School of Medicine used diffusion tensor imaging (DTI) to scan the brain of 10 young people who had smoked cannabis during adolescence. The participants were between 17 and 30 years old, they had smoked at least two to three times a week for one or more years during adolescence and had no personal or family history of mental health problems. They were matched for sex, age and social class of parents with 10 controls who had not smoked cannabis regularly as teenagers.

DTI is a magnetic resonance imaging (MRI) technique that enables a detailed look at the organisation of nerves in the brain and the measurement of brain volume.

DeLisi and her colleagues found no significant differences in brain integrity and brain volume between cannabis smokers and non-smokers. This preliminary study suggests that moderate cannabis use has no direct adverse effects on brain structure and integrity. The authors warn however, that more research is necessary, both in a larger group of people and to see the effects of heavier use.

http://www.biomedcentral.com

[budman]

Pot Impairs Learning in Adolescent Rats: Study

The main active ingredient in marijuana leads to short-term impairment of learning in adolescent rats, but doesn't seem to affect adults similarly, Duke University Medical Center researchers report.

Their study compared the effects of delta9-tetrahydrocannabinol (THC) on the memory ability of adolescent and adult rats to see if the animals, and perhaps humans, are more sensitive to THC at certain stages. Researchers found that chronic exposure to THC during adolescence may not lead to long-term damage persisting into adulthood, but said the finding should be interpreted cautiously, since other studies have suggested the damage may be longer-lasting.

The study tested the effects of THC exposure on memory and learning by dosing rats with varying amounts, training them to navigate a "water maze," and then measuring how well the rats remembered how to get to a stationary platform in the water. After the THC had cleared the rats' systems and the adolescents had reached full maturity, the researchers tested how well they performed in the water maze. The chronic exposure appeared to have no effect on the rats' later learning abilities, the study found.

The findings appear in the March 2006 issue of the journal Pharmacology, Biochemistry and Behavior, which is expected to be published June 8.

"There are plenty of good reasons for adolescents to not smoke pot," said H. Scott Swartzwelder, a professor of psychiatry at Duke and the Durham Veterans Affairs Medical Center and the senior author on the study. "The teen years require a lot of learning and preparation for adulthood."


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