Heavy marijuana use has been linked with impaired motivation, attention, learning and memory, but common beliefs maintain that casual use of the drug does not result in any negative outcomes. Now, a new study suggests young adults who smoke marijuana at least once a week have altered areas of the brain involved in emotion and motivation. The study was reported in Medical News Today.
The researchers, from Northwestern University and Massachusetts General Hospital/Harvard Medical School, published their results in the Journal of Neuroscience.
The researchers, including Jodi Gilman, PhD, used magnetic resonance imaging (MRI) to analyze the brains of 40 subjects between the ages of 18 and 25 years old who smoked marijuana at least once per week. They then compared these brain scans with the scans of individuals with little or no history of marijuana use.
Each marijuana user was asked to estimate his or her drug intake over a 3-month period, providing the number of days and amount they smoked.
Psychiatric evaluation ruled out the chance that the marijuana users were dependent on the drug, however, the MRI images showed "significant" brain differences.
Compared with the non-smokers, the marijuana users had a larger nucleus accumbens - the brain region involved in reward processing. Additionally, it had an altered shape and structure in the brains of the marijuana users.
And the more marijuana the smokers used, the greater the abnormalities in both the nucleus accumbens and the amygdala, a region involved in emotion.
Dr. Hans Breiter, a co-author of the study, says their findings raise "a strong challenge to the idea that casual marijuana use isn't associated with bad consequences."
"Abnormal neuronal growth in the nucleus accumbens could be an indication that the brain is forming new connections that may encourage further use of marijuana. The study results fit with animal studies that show when rats are given THC, their brains rewire and form many new connections. It may be that we're seeing a type of drug learning in the brain," Dr. Breiter said.
SEE ALSO:
New Research Links Long-Term Marijuana Use to Schizophrenia
http://www.cadca.org/resources/detail/new-research-links-long-term-marijuana-use-schizophrenia
Marijuana Smoking Determined to Permanently Lower One’s IQ
http://www.cadca.org/resources/detail/marijuana-smoking-determined-permanently-lower-one%E2%80%99s-iq
The researchers, including Jodi Gilman, PhD, used magnetic resonance imaging (MRI) to analyze the brains of 40 subjects between the ages of 18 and 25 years old who smoked marijuana at least once per week. They then compared these brain scans with the scans of individuals with little or no history of marijuana use.
Each marijuana user was asked to estimate his or her drug intake over a 3-month period, providing the number of days and amount they smoked.
Psychiatric evaluation ruled out the chance that the marijuana users were dependent on the drug, however, the MRI images showed "significant" brain differences.
Compared with the non-smokers, the marijuana users had a larger nucleus accumbens - the brain region involved in reward processing. Additionally, it had an altered shape and structure in the brains of the marijuana users.
And the more marijuana the smokers used, the greater the abnormalities in both the nucleus accumbens and the amygdala, a region involved in emotion.
Dr. Hans Breiter, a co-author of the study, says their findings raise "a strong challenge to the idea that casual marijuana use isn't associated with bad consequences."
"Abnormal neuronal growth in the nucleus accumbens could be an indication that the brain is forming new connections that may encourage further use of marijuana. The study results fit with animal studies that show when rats are given THC, their brains rewire and form many new connections. It may be that we're seeing a type of drug learning in the brain," Dr. Breiter said.
SEE ALSO:
New Research Links Long-Term Marijuana Use to Schizophrenia
http://www.cadca.org/resources/detail/new-research-links-long-term-marijuana-use-schizophrenia
Marijuana Smoking Determined to Permanently Lower One’s IQ
http://www.cadca.org/resources/detail/marijuana-smoking-determined-permanently-lower-one%E2%80%99s-iq
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