Navigation Links
Heavy marijuana users have abnormal brain structure and poor memory
Date:12/16/2013

CHICAGO --- Teens who were heavy marijuana users -- smoking it daily for about three years -- had abnormal changes in their brain structures related to working memory and performed poorly on memory tasks, reports a new Northwestern Medicine study.

A poor working memory predicts poor academic performance and everyday functioning.

The brain abnormalities and memory problems were observed during the individuals' early twenties, two years after they stopped smoking marijuana, which could indicate the long-term effects of chronic use. Memory-related structures in their brains appeared to shrink and collapse inward, possibly reflecting a decrease in neurons.

The study also shows the marijuana-related brain abnormalities are correlated with a poor working memory performance and look similar to schizophrenia-related brain abnormalities. Over the past decade, Northwestern scientists, along with scientists at other institutions, have shown that changes in brain structure may lead to changes in the way the brain functions.

This is the first study to target key brain regions in the deep subcortical gray matter of chronic marijuana users with structural MRI and to correlate abnormalities in these regions with an impaired working memory. Working memory is the ability to remember and process information in the moment and -- if needed -- transfer it to long-term memory. Previous studies have evaluated the effects of marijuana on the cortex, and few have directly compared chronic marijuana use in otherwise healthy individuals and individuals with schizophrenia.

The younger the individuals were when they started chronically using marijuana, the more abnormally their brain regions were shaped, the study reports. The findings suggest that these regions related to memory may be more susceptible to the effects of the drug if abuse starts at an earlier age.

"The study links the chronic use of marijuana to these concerning brain abnormalities that appear to last for at least a few years after people stop using it," said lead study author Matthew Smith, an assistant research professor in psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine. "With the movement to decriminalize marijuana, we need more research to understand its effect on the brain."

The paper will be published Dec. 16 in the journal Schizophrenia Bulletin.

In the U.S., marijuana is the most commonly used illicit drug and young adults have the highest -- and growing -- prevalence of use. Decriminalization of the drug may lead to greater use.

Because the study results examined one point in time, a longitudinal study is needed to definitively show if marijuana is responsible for the brain changes and memory impairment. It is possible that the abnormal brain structures reveal a pre-existing vulnerability to marijuana abuse. But evidence that the younger a subject started using the drug the greater his brain abnormality indicates marijuana may be the cause, Smith said.

The groups in the study started using marijuana daily between 16 to 17 years of age for about three years. At the time of the study, they had been marijuana free for about two years. A total of 97 subjects participated, including matched groups of healthy controls, subjects with a marijuana use disorder, schizophrenia subjects with no history of substance use disorders, and schizophrenia subjects with a marijuana use disorder. The subjects who used marijuana did not abuse any other drugs.

Few studies have examined marijuana's effect on the deep regions in the brain -- the 'subcortical gray matter' below the noodle-shaped cortex. The study also is unique in that it looked at the shapes of the striatum, globus pallidus and thalamus, structures in the subcortex that are critical for motivation and working memory.

The Marijuana and Schizophrenia Connection

Chronic use of marijuana may contribute to changes in brain structure that are associated with having schizophrenia, the Northwestern research shows. Of the 15 marijuana smokers who had schizophrenia in the study, 90 percent started heavily using the drug before they developed the mental disorder. Marijuana abuse has been linked to developing schizophrenia in prior research.

"The abuse of popular street drugs, such as marijuana, may have dangerous implications for young people who are developing or have developed mental disorders," said co-senior study author John Csernansky, M.D., chair of psychiatry and behavioral sciences at Northwestern University Feinberg School of Medicine and Northwestern Memorial Hospital. "This paper is among the first to reveal that the use of marijuana may contribute to the changes in brain structure that have been associated with having schizophrenia."

Chronic marijuana use could augment the underlying disease process associated with schizophrenia, Smith noted. "If someone has a family history of schizophrenia, they are increasing their risk of developing schizophrenia if they abuse marijuana," he said.

While chronic marijuana smokers and chronic marijuana smokers with schizophrenia both had brain changes related to the drug, subjects with the mental disorder had greater deterioration in the thalamus. That structure is the communication hub of the brain and is critical for learning, memory and communications between brain regions. The brain regions examined in this study also affect motivation, which is already notably impaired in people with schizophrenia.

"A tremendous amount of addiction research has focused on brain regions traditionally connected with reward/aversion function, and thus motivation," noted co-senior study author Hans Breiter, M.D., professor of psychiatry and behavioral sciences and director of the Warren Wright Adolescent Center at Feinberg and Northwestern Memorial. "This study very nicely extends the set of regions of concern to include those involved with working memory and higher level cognitive functions necessary for how well you organize your life and can work in society."

"If you have schizophrenia and you frequently smoke marijuana, you may be at an increased risk for poor working memory, which predicts your everyday functioning," Smith said.


'/>"/>

Contact: Marla Paul
marla-paul@northwestern.edu
312-503-8928
Northwestern University
Source:Eurekalert

Related medicine news :

1. Heavy drinking is bad for marriage if 1 spouse drinks, but not both
2. Heavy Drinking Can Cause Anemia And Dementia
3. Lida Daidaihua and Lishou Pink By NLslimming.com Are Now Offered At Heavy Discounts
4. New Colorstar Plush Indoor Wiper Mats from Martinson-Nicholls Provide Comfort and Durability in Heavy Foot Traffic Areas
5. Parents with heavy TV viewing more likely to feed children junk food
6. Living Near Heavy Traffic May Harm Kidney Function
7. Exercise May Blunt Heavy Drinkings Effect on Brain
8. CAMH study shows mental illness associated with heavy cannabis use
9. Genes May Dictate Teens Susceptibility to Heavy Smoking
10. Lung Cancer Asbestos Victims Center Now Urges US Navy Veterans With Lung Cancer To Call Them If They Had Heavy Exposure To Asbestos On A US Navy Ship
11. Heavy moms-to-be at greater risk of c-section
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... A recent ... that most people are unfamiliar with. The article goes on to state that individuals ... also many of these less common operations such as calf and cheek reduction. The ...
(Date:6/24/2016)... ... June 24, 2016 , ... Marcy was in a crisis. Her son James, eight, was out ... family verbally and physically. , “When something upset him, he couldn’t control his emotions,” remembers ... would throw rocks at my other children and say he was going to kill them. ...
(Date:6/24/2016)... Francisco, CA (PRWEB) , ... June 24, 2016 ... ... CitiDent, is now offering micro-osteoperforation for accelerated orthodontic treatment. Dr. Cheng has extensive ... self-ligating Damon brackets , AcceleDent, and accelerated osteogenic orthodontics. , Micro-osteoperforation ...
(Date:6/24/2016)... (PRWEB) , ... June 24, 2016 , ... People across ... in Genome magazine’s Code Talker Award, an essay contest in which patients and their ... award to be presented at the 2016 National Society of Genetic Counselors (NSGC) Annual ...
(Date:6/24/2016)... Las Vegas, Nevada (PRWEB) , ... June 24, ... ... their Las Vegas client, The Grove Investment Group (TGIG), has initiated cultivation and ... The Grove, in Las Vegas and Pahrump, Nevada. , Puradigm is the manufacturer ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... June 24, 2016 Dehaier Medical Systems Ltd. ... which develops, markets and sells medical devices and wearable ... signed a strategic cooperation agreement with Hongyuan Supply Chain ... Chain") on June 20, 2016, to develop Dehaier,s new ... cooperation agreement, Dehaier will leverage Hongyuan Supply Chain,s sales ...
(Date:6/24/2016)...   Pulmatrix, Inc ., (NASDAQ: PULM ... announced today that it was added to the Russell ... comprehensive set of U.S. and global equity indexes on ... milestone for Pulmatrix," said Chief Executive Officer Robert ... progress in developing drugs for crucial unmet medical needs, ...
(Date:6/23/2016)... 2016 Research and Markets has announced ... Forecast to 2022" report to their offering. ... the patients with kidney failure, it replaces the function of ... patient,s blood and thus the treatment helps to keep the ... balance. Increasing number of ESRD patients & ...
Breaking Medicine Technology: