July 24, 2013 — Regular marijuana use in adolescence, but not adulthood, may permanently impair brain function and cognition, and may increase the risk of developing serious psychiatric disorders such as schizophrenia, according to a recent study from the University of Maryland School of Medicine. Researchers hope that the study, published in Neuropsychopharmacology -- a publication of the journal Nature -- will help to shed light on the potential long-term effects of marijuana use, particularly as lawmakers in Maryland and elsewhere contemplate legalizing the drug.
"Over the past 20 years, there has been a major controversy about the long-term effects of marijuana, with some evidence that use in adolescence could be damaging," says the study's senior author Asaf Keller, Ph.D., Professor of Anatomy and Neurobiology at the University of Maryland School of Medicine. "Previous research has shown that children who started using marijuana before the age of 16 are at greater risk of permanent cognitive deficits, and have a significantly higher incidence of psychiatric disorders such as schizophrenia. There likely is a genetic susceptibility, and then you add marijuana during adolescence and it becomes the trigger."
"Adolescence is the critical period during which marijuana use can be damaging," says the study's lead author, Sylvina Mullins Raver, a Ph.D. candidate in the Program in Neuroscience in the Department of Anatomy and Neurobiology at the University of Maryland School of Medicine. "We wanted to identify the biological underpinnings and determine whether there is a real, permanent health risk to marijuana use."
The scientists -- including co-author Sarah Paige Haughwout, a research technician in Dr. Keller's laboratory -- began by examining cortical oscillations in mice. Cortical oscillations are patterns of the activity of neurons in the brain and are believed to underlie the brain's various functions. These oscillations are very abnormal in schizophrenia and in other psychiatric disorders. The scientists exposed young mice to very low doses of the active ingredient in marijuana for 20 days, and then allowed them to return to their siblings and develop normally.
"In the adult mice exposed to marijuana ingredients in adolescence, we found that cortical oscillations were grossly altered, and they exhibited impaired cognitive abilities," says Ms. Raver. "We also found impaired cognitive behavioral performance in those mice. The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood."
The scientists repeated the experiment, this time administering marijuana ingredients to adult mice that had never been exposed to the drug before. Their cortical oscillations and ability to perform cognitive behavioral tasks remained normal, indicating that it was only drug exposure during the critical period of adolescence that impaired cognition through this mechanism. The researchers took the next step in their studies, trying to pinpoint the mechanisms underlying these changes and the time period in which they occur.
"We looked at the different regions of the brain," says Dr. Keller. "The back of the brain develops first, and the frontal parts of the brain develop during adolescence. We found that the frontal cortex is much more affected by the drugs during adolescence. This is the area of the brain controls executive functions such as planning and impulse control. It is also the area most affected in schizophrenia."
Dr. Keller's team believes that the results have indications for humans as well. They will continue to study the underlying mechanisms that cause these changes in cortical oscillations. "The purpose of studying these mechanisms is to see whether we can reverse these effects," says Dr. Keller. "We are hoping we will learn more about schizophrenia and other psychiatric disorders, which are complicated conditions. These cognitive symptoms are not affected by medication, but they might be affected by controlling these cortical oscillations."
"This study is an example of how the basic science research taking place in our state-of-the-art laboratories can impact human health and inform health policy," says E. Albert Reece, M.D., Ph.D., M.B.A., Vice President for Medical Affairs at the University of Maryland and John Z. and Akiko K. Bowers Distinguished Professor and Dean of the University of Maryland School of Medicine. "We are proud of this groundbreaking discovery and look forward to watching this research develop further."
Tekonline.org 10 years ago
Prog Neuropsychopharmacol Biol Psychiatry. 2013 Aug 1. pii: S0278-5846(13)00162-0. doi: 10.1016/j.pnpbp.2013.07.020. [Epub ahead of print]
Cannabis abuse in adolescence and the risk of psychosis: A brief review of the precli ... read full comment
Prog Neuropsychopharmacol Biol Psychiatry. 2013 Aug 1. pii: S0278-5846(13)00162-0. doi: 10.1016/j.pnpbp.2013.07.020. [Epub ahead of print]
Cannabis abuse in adolescence and the risk of psychosis: A brief review of the preclinical evidence.
Rubino T, Parolaro D.
Source
Department of Theoretical and Applied Sciences, Biomedical Research Division, University of Insubria, via Manara 7, 21052 Busto Arsizio VA, Italy.
Abstract
Epidemiological studies suggest that Cannabis use during adolescence confers an increased risk for developing psychotic symptoms later in life. However, despite their interest, the epidemiological data are not conclusive, due to their heterogeneity; thus modeling the adolescent phase in animals is useful for investigating the impact of Cannabis use on deviations of adolescent brain development that might confer a vulnerability to later psychotic disorders. Although scant, preclinical data seem to support the presence of impaired social behaviors, cognitive and sensorimotor gating deficits as well as psychotic-like signs in adult rodents after adolescent cannabinoid exposure, clearly suggesting that this exposure may trigger a complex behavioral phenotype closely resembling a schizophrenia-like disorder. Similar treatments performed at adulthood were not able to produce such phenotype, thus pointing to a vulnerability of the adolescent brain towards cannabinoid exposure. The neurobiological substrate of the adolescent vulnerability is still largely unknown and experimental studies need to elucidate the cellular and molecular mechanism underlying these effects. However, the few data available seem to suggest that heavy adolescent exposure to cannabinoids is able to modify neuronal connectivity in specific brain areas long after the end of the treatment. This is likely due to disruption of maturational events within the endocannabinoid system during adolescence that in turn impact on the correct neuronal refinement peculiar of the adolescent brain, thus leading to altered adult brain functionality and behavior.
So in effect are you suggesting that we legalize marijuana in Ghana? note that places where its legalize,there are mechanisms in place to control the production and usage.come again bro!!
So in effect are you suggesting that we legalize marijuana in Ghana? note that places where its legalize,there are mechanisms in place to control the production and usage.come again bro!!
Kakraba Cromwell 10 years ago
I am very disappointed with your conclusion.
Honestly you are making the same mistake that was used in the 19th century to legalize cocaine for a time. What you are forgetting is the truth
I am very disappointed with your conclusion.
Honestly you are making the same mistake that was used in the 19th century to legalize cocaine for a time. What you are forgetting is the truth
Tekonline.org 10 years ago
Contact: Kristen Lidke Woodward
kwoodwar@fhcrc.org
206-667-5095
Fred Hutchinson Cancer Research Center
Marijuana use linked to increased risk of testicular cancer
Risk appears to be elevated particularly among frequ ... read full comment
Contact: Kristen Lidke Woodward
kwoodwar@fhcrc.org
206-667-5095
Fred Hutchinson Cancer Research Center
Marijuana use linked to increased risk of testicular cancer
Risk appears to be elevated particularly among frequent and/or long-term users
SEATTLE – Frequent and/or long-term marijuana use may significantly increase a man's risk of developing the most aggressive type of testicular cancer, according to a study by researchers at Fred Hutchinson Cancer Research Center. The study results were published online Feb. 9 in the journal Cancer.
The researchers found that being a marijuana smoker at the time of diagnosis was associated with a 70 percent increased risk of testicular cancer. The risk was particularly elevated (about twice that of those who never smoked marijuana) for those who used marijuana at least weekly and/or who had long-term exposure to the substance beginning in adolescence.
The results also suggested that the association with marijuana use might be limited to nonseminoma, a fast-growing testicular malignancy that tends to strike early, between ages 20 and 35, and accounts for about 40 percent of all testicular-cancer cases.
Since the 1950s, the incidence of the two main cellular subtypes of testicular cancer, nonseminoma and seminoma – the more common, slower growing kind that strikes men in their 30s and 40s – has increased by 3 percent to 6 percent per year in the U.S., Canada, Europe, Australia and New Zealand. During the same time period, marijuana use in North America, Europe and Australia has risen accordingly, which is one of several factors that led the researchers to hypothesize a potential association.
"Our study is not the first to suggest that some aspect of a man's lifestyle or environment is a risk factor for testicular cancer, but it is the first that has looked at marijuana use," said author Stephen M. Schwartz, M.P.H., Ph.D., an epidemiologist and member of the Public Health Sciences Division at the Hutchinson Center.
Established risk factors for testicular cancer include a family history of the disease, undescended testes and abnormal testicular development. The disease is thought to begin in the womb, when some fetal germ cells (those that eventually make sperm in adulthood) fail to develop properly and become vulnerable to malignancy. Later, during adolescence and adulthood, it is thought that exposure to male sex hormones coaxes these cells to become cancerous.
"Just as the changing hormonal environment of adolescence and adulthood can trigger undifferentiated fetal germ cells to become cancerous, it has been suggested that puberty is a 'window of opportunity' during which lifestyle or environmental factors also can increase the risk of testicular cancer," said senior author Janet R. Daling, Ph.D., an epidemiologist who is also a member of the Center's Public Health Sciences Division. "This is consistent with the study's findings that the elevated risk of nonseminoma-type testicular cancer in particular was associated with marijuana use prior to age 18."
Chronic marijuana exposure has multiple adverse effects on the endocrine and reproductive systems, primarily decreased sperm quality. Other possible effects include decreased testosterone and male impotency. Because male infertility and poor semen quality also have been linked to an increased risk of testicular cancer, this further reinforced the researchers' hypothesis that marijuana use may be a risk factor for the disease.
Daling first got the idea to explore a possible association between marijuana use and testicular cancer about eight years ago, when she attended a talk by a physician at the University of Washington who presented findings that only two organs, the brain and the testes, had receptors for tetrahydrocannabinol, or THC, the main psychoactive component of marijuana. Since then, a number of other sites have been found to contain THC receptors, including the heart, uterus, spleen and immune-system cells.
The male reproductive system also naturally produces a cannabinoid-like chemical that is thought to have a protective effect against cancer. The authors speculate that marijuana use may disrupt this anti-tumor effect, which could be another explanation for the possible link between marijuana and increased risk of testicular cancer.
For the population-based, case-control study, Daling, Schwartz and colleagues interviewed 369 Seattle-Puget Sound-area men, ages 18 to 44, who had been diagnosed with testicular cancer about their history of marijuana use. For comparison purposes they also assessed marijuana use among 979 randomly selected age- and geography-matched healthy controls. (More than 90 percent of the cases and 80 percent of the controls in the study were Hispanic or non-Hispanic white men, due to the fact that testicular cancer is very rare in African-Americans, and because the Seattle-Puget Sound region has a relatively small African-American population.)
Study participants were also asked about other habits that may be correlated with marijuana use, including smoking and alcohol consumption. Even after statistically controlling for these lifestyle factors, as well as other risk factors, such as first-degree family history of testicular cancer and a history of undescended testes, marijuana use emerged as a significant, independent risk factor for testicular cancer.
The researchers emphasize that their results are not definitive, but rather open a door to more research questions.
"Our study is the first inkling that marijuana use may be associated with testicular cancer, and we still have a lot of unanswered questions," Schwartz said, such as why marijuana appears to be associated with only one type of testicular cancer. "We need to conduct additional research to see whether the association can be observed in other populations, and whether measurement of molecular markers connected to the pathways through which marijuana could influence testicular cancer development helps clarify any association that exists," he said.
In future studies the researchers plan to measure the expression of cannabinoid receptors in both seminomatous and nonseminomatous tumor tissue from the cases in the study, and to see whether variation in the genes for the receptors and other molecules involved in cannabinoid signaling influences the risk of testicular cancer.
In the meantime, Schwartz said, "What young men should know is that first, we know very little about the long-term health consequences of marijuana smoking, especially heavy marijuana smoking; and second, our study provides some evidence that testicular cancer could be one adverse consequence," he said. "So, in the absence of more certain information, a decision to smoke marijuana recreationally means that one is taking a chance on one's future health."
###
The National Cancer Institute, the National Institute on Drug Abuse and funds from the Hutchinson Center supported this research, which also involved researchers from the University of Washington, Vanderbilt University and Cincinnati Children's Research Foundation.
According to the National Cancer Institute, testicular cancer is very rare, accounting for only 1 percent of cancers in U.S. men. About 8,000 men are diagnosed with testicular cancer each year, and about 390 die of the disease annually. It is the most common form of cancer in men between the ages of 15 and 34 and is most common in white men, especially those of Scandinavian descent.
At Fred Hutchinson Cancer Research Center, our interdisciplinary teams of world-renowned scientists and humanitarians work together to prevent, diagnose and treat cancer, HIV/AIDS and other diseases. Our researchers, including three Nobel laureates, bring a relentless pursuit and passion for health, knowledge and hope to their work and to the world. For more information, please visit fhcrc.org.
Tekonline.org 10 years ago
Even though this study might indicate caucasians might have more to worry about the carcinogenic effect of the drug than African-Americans, no study has yet been conducted on Africans living in Africa.
Even though this study might indicate caucasians might have more to worry about the carcinogenic effect of the drug than African-Americans, no study has yet been conducted on Africans living in Africa.
princewilly@ymail.com 10 years ago
Two guys were picked up by the cops for selling drugs and appeared in court before the judge. The judge said:
You seem like nice young men, and I'd like to give you a second chance rather than jail time. I want you to go o ... read full comment
Two guys were picked up by the cops for selling drugs and appeared in court before the judge. The judge said:
You seem like nice young men, and I'd like to give you a second chance rather than jail time. I want you to go out this weekend and try to show others the evils of drug use and persuade them to give up drugs forever. I'll see you back in court Monday."
Monday, the two guys were in court, and the judge said to the first one:
"How did you do over the weekend?"
"Well, your honour, I persuaded 10 people to give up drugs forever."
"10 people? That's wonderful. What did you tell them?"
"I used a diagram, your honour. I drew two circles like this: O o and told them this (the big circle) is your brain before drugs and this (small circle) is your brain after drugs."
"That's admirable," said the judge. "And you, how did you do?" (to the 2nd guy)
"Well, your honour, I persuaded 50 people to give up drugs forever."
"50 people! That's amazing! How did you manage to do that!"
"Well, I used the same two circles. I pointed to the small circle and told them, 'This is your asshole before prison...."
truth 10 years ago
lets stop pretending we dont ALL already smoke , by all i mean us and the police and even our parents and presidents and presidential candidates . lol
lets stop pretending we dont ALL already smoke , by all i mean us and the police and even our parents and presidents and presidential candidates . lol
Lori Ann 10 years ago
I like my cigarettes. And as far as safety goes, the small pox shots we were given as children were suppose to have cancer causing agents in it . Look that up. No one has ever proved to me that cigarettes is the only thing th ... read full comment
I like my cigarettes. And as far as safety goes, the small pox shots we were given as children were suppose to have cancer causing agents in it . Look that up. No one has ever proved to me that cigarettes is the only thing that cause people to get cancer. There are babies born to parents who never smoked that have cancer. And if given the choice of dying in the electric chair or a smoke filled room, well guess which one I would pick. We never know how much time we have on this earth. So , I say live happy while you can. I smoke , but there is no guarantee I won't get hit by a bus or something.Cigarettes might not be everyone's cup of tea, but allow others to have their freedom too I say. And marijuana should be legalized just like in Colorado . And it should be legalized now.
Marijuana Use in Adolescence May Cause Permanent Brain Abnormalities, Mouse Study Suggests
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Regular marijuana use in adolescence, but not adulthood, may permanently impair brain function and cognition, and may incr ...
read full comment
Prog Neuropsychopharmacol Biol Psychiatry. 2013 Aug 1. pii: S0278-5846(13)00162-0. doi: 10.1016/j.pnpbp.2013.07.020. [Epub ahead of print]
Cannabis abuse in adolescence and the risk of psychosis: A brief review of the precli ...
read full comment
So in effect are you suggesting that we legalize marijuana in Ghana? note that places where its legalize,there are mechanisms in place to control the production and usage.come again bro!!
I am very disappointed with your conclusion.
Honestly you are making the same mistake that was used in the 19th century to legalize cocaine for a time. What you are forgetting is the truth
Contact: Kristen Lidke Woodward
kwoodwar@fhcrc.org
206-667-5095
Fred Hutchinson Cancer Research Center
Marijuana use linked to increased risk of testicular cancer
Risk appears to be elevated particularly among frequ ...
read full comment
Even though this study might indicate caucasians might have more to worry about the carcinogenic effect of the drug than African-Americans, no study has yet been conducted on Africans living in Africa.
Two guys were picked up by the cops for selling drugs and appeared in court before the judge. The judge said:
You seem like nice young men, and I'd like to give you a second chance rather than jail time. I want you to go o ...
read full comment
lets stop pretending we dont ALL already smoke , by all i mean us and the police and even our parents and presidents and presidential candidates . lol
I like my cigarettes. And as far as safety goes, the small pox shots we were given as children were suppose to have cancer causing agents in it . Look that up. No one has ever proved to me that cigarettes is the only thing th ...
read full comment