Cannabis use precedes the onset of psychotic symptoms in young people

March 1st, 2011 in Medicine & Health / Psychology & Psychiatry 

Cannabis use during adolescence and young adulthood increases the risk of psychotic symptoms, while continued cannabis use may increase the risk for psychotic disorder in later life, concludes a new study published in the British Medical Journal today.

Cannabis is the most commonly used illicit drug in the world, particularly among adolescents, and is consistently linked with an increased risk for mental illness. However, it is not clear whether the link between cannabis and psychosis is causal, or whether it is because people with psychosis use cannabis to self medicate their symptoms.

So a team of researchers, led by Professor Jim van Os from Maastricht University in the Netherlands, set out to investigate the association between cannabis use and the incidence and persistence of psychotic symptoms over 10 years.

The study took place in Germany and involved a random sample of 1,923 adolescents and young adults aged 14 to 24 years.

The researchers excluded anyone who reported cannabis use or pre-existing psychotic symptoms at the start of the study so that they could examine the relation between new (incident) cannabis use and psychotic symptoms.

The remaining participants were then assessed for cannabis use and psychotic symptoms at three time points over the study period (on average four years apart).

Incident cannabis use almost doubled the risk of later incident psychotic symptoms, even after accounting for factors such as age, sex, socioeconomic status, use of other drugs, and other psychiatric diagnoses. Furthermore, in those with cannabis use at the start of the study, continued use of cannabis over the study period increased the risk of persistent psychotic symptoms

There was no evidence for self medication effects as psychotic symptoms did not predict later cannabis use.

These results "help to clarify the temporal association between cannabis use and psychotic experiences," say the authors. "In addition, cannabis use was confirmed as an environmental risk factor impacting on the risk of persistence of psychotic experiences."

The major challenge is to deter enough young people from using cannabis so that the prevalence of psychosis is reduced, say experts from Australia in an accompanying editorial.

Professor Wayne Hall from the University of Queensland and Professor Louisa Degenhardt from the Burnet Institute in Melbourne, question the UK's decision to retain criminal penalties for cannabis use, despite evidence that removing such penalties has little or no detectable effect on rates of use. They believe that an informed cannabis policy "should be based not only on the harms caused by cannabis use, but also on the harms caused by social policies that attempt to discourage its use, such as criminal penalties for possession and use."

Provided by British Medical Journal

"Cannabis use precedes the onset of psychotic symptoms in young people." March 1st, 2011. 
http://www.physorg.com/news/2011-03-cannabis-onset-psychotic-symptoms-young.html

Synthetic cannabis linked to extended psychosis

May 18th, 2011 in Psychology & Psychiatry 


Case studies indicate the recreational use of synthetic cannabis may lead to psychosis that can last for days or months in some cases, according to a study at the American Psychiatric Association Annual Meeting in Hawaii.

Researchers at the Naval Medical Center in San Diego followed ten patients hospitalized for psychosis apparently induced by the use of synthetic cannabis, commonly known as “Spice,” “K2,” “Blaze,” and “Red X Dawn.” These are plant material coated with varying combinations of synthetic cannabinoids, which act on the body in a similar way to chemicals found in cannabis. The compounds have not been approved by the FDA for human consumption and little is known about their safety.

The ten patients studied ranged in age from 21 to 25 years old and after use of “Spice” experienced ongoing psychotic symptoms, including auditory and visual hallucinations, paranoid delusions, odd or flat affect, thought blocking, disorganized speech, thoughts of suicide, insomnia, slowed reaction times, agitation and anxiety. Psychotic symptoms generally resolved between five and eight days after admission, but in some cases continued three months or longer.

The research was scheduled for presentation at 1 p.m. Saturday, May 14, at the American Psychiatric Association 164 the Annual Meeting, which runs May 14-18 at the Hawaii Convention Center in Honolulu.

Provided by American Psychiatric Association


"Synthetic cannabis linked to extended psychosis." May 18th, 2011. http://medicalxpress.com/news/2011-05-synthetic-cannabis-linked-psychosis.html

Molecular imaging shows chronic marijuana smoking affects brain chemistry

June 6th, 2011 in Neuroscience 

Definitive proof of an adverse effect of chronic marijuana use revealed at SNM's 58th Annual Meeting could lead to potential drug treatments and aid other research involved in cannabinoid receptors, a neurotransmission system receiving a lot of attention. Scientists used molecular imaging to visualize changes in the brains of heavy marijuana smokers versus non-smokers and found that abuse of the drug led to a decreased number of cannabinoid CB1 receptors, which are involved in not just pleasure, appetite and pain tolerance but a host of other psychological and physiological functions of the body.

"Addictions are a major medical and socioeconomic problem," says Jussi Hirvonen, MD, PhD, lead author of the collaborative study between the National Institute of Mental Health and National Institute on Drug Abuse, Bethesda, Md. "Unfortunately, we do not fully understand the neurobiological mechanisms involved in addiction. With this study, we were able to show for the first time that people who abuse cannabis have abnormalities of the cannabinoid receptors in the brain. This information may prove critical for the development of novel treatments for cannabis abuse. Furthermore, this research shows that the decreased receptors in people who abuse cannabis return to normal when they stop smoking the drug."

According to the National Institute on Drug Abuse, marijuana is the number-one illicit drug of choice in America. The psychoactive chemical in marijuana, or cannabis, is delta-9-tetrahydrocannabinol (THC), which binds to numerous cannabinoid receptors in the brain and throughout the body when smoked or ingested, producing a distinctive high. Cannabinoid receptors in the brain influence a range of mental states and actions, including pleasure, concentration, perception of time and memory, sensory perception, and coordination of movement. There are also cannabinoid receptors throughout the body involved in a wide range of functions of the digestive, cardiovascular, respiratory and other systems of the body. Currently two subtypes of cannabinoid receptors are known, CB1 and CB2, the former being involved mostly in functions of the central nervous system and the latter more in functions of the immune system and in stem cells of the circulatory system. For this study, researchers recruited 30 chronic daily cannabis smokers who were then monitored at a closed inpatient facility for approximately four weeks. The subjects were imaged using positron emission tomography (PET), which provides information about physiological processes in the body. Subjects were injected with a radioligand, 18F-FMPEP-d2, which is a combination of a radioactive fluorine isotope and a neurotransmitter analog that binds with CB1 brain receptors.

Results of the study show that receptor number was decreased about 20 percent in brains of cannabis smokers when compared to healthy control subjects with limited exposure to cannabis during their lifetime. These changes were found to have a correlation with the number of years subjects had smoked. Of the original 30 cannabis smokers, 14 of the subjects underwent a second PET scan after about a month of abstinence. There was a marked increase in receptor activity in those areas that had been decreased at the outset of the study, an indication that while chronic cannabis smoking causes downregulation of CB1 receptors, the damage is reversible with abstinence. Information gleaned from this and future studies may help other research exploring the role of PET imaging of CB1 receptors—not just for drug use, but also for a range of human diseases, including metabolic disease and cancer.

More information: Scientific Paper 10: J. Hirvonen, R. Goodwin, C. Li1, G. Terry, S. Zoghbi, C Morse, V. Pike, N. Volkow, M. Huestis, R. Innis, National Institute of Mental Health, Bethesda, MD; National Institute on Drug Abuse, Baltimore, MD; "Reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in chronic daily cannabis smokers," SNM's 58th Annual Meeting, June 4-8, 2011, San Antonio, TX.

Provided by Society of Nuclear Medicine  "Molecular imaging shows chronic marijuana smoking affects brain chemistry." June 6th, 2011. 

http://medicalxpress.com/news/2011-06-molecular-imaging-chronic-marijuana-affects.html

Drinking, cannabis use and psychological distress increase, CAMH survey finds

June 13th, 2011 in Health 

The latest survey of Ontario adults from the Centre for Addiction and Mental Health (CAMH) shows increasing rates of daily drinking and cannabis use and high levels of psychological distress. The results of the 2009 CAMH Monitor survey, the longest running survey tracking mental health and addiction indicators among adults in Ontario, were published today.

Alcohol:-  The proportion of adults reporting daily drinking increased from 5.3% in 2002 to over 9% in 2009. The average number of drinks consumed weekly among drinkers has also increased from 3 drinks to 4.6 drinks, and the proportion of adults exceeding low-risk drinking guidelines remains at elevated levels (22%). However, there were also some encouraging findings: there was a significant decline in binge drinking from 12.6% in 2006 to 7.1% in 2009, and the decline was evident especially among young adults, from 24% to 11.5%. Although driving within an hour of consuming two or more drinks has shown a steady decline in the past years, from 13.1% in 1996 to 6.9% in 2009, there is evidence that this trend has reversed among young adults. Driving after drinking posted a significant increase among 18 to 29 year olds, from 7.7% in 2005 to 12.8% in 2009. "The data tell us that while the number of people who drink alcohol has not changed, the way they are drinking has -- people are drinking more often and may be consuming more alcohol when they do drink, although there may be fewer binge occasions," said Dr. Robert Mann, CAMH Senior Scientist and lead investigator on the study. "We know that the more access people have to alcohol, the more people will drink, leading to more instances of drinking and driving. Measures such as Random Breath Testing and lowering legal limits to .05% can reduce drunk driving deaths. The implementation of .05% legislation in British Columbia appears to have resulted in a 50% decrease in drinking and driving deaths in that province."

Cannabis:- The prevalence of cannabis use has been steadily increasing from 8.7% in 1996 to 13.3% in 2009, for both men and women and among all age groups. Along with this, there was almost a 2-fold increase in cannabis use among those aged 18-29, from 18.3% to 35.8%. "These increases are of concern to us," stated Dr. Mann. "We know that cannabis use may increase the risk of psychosis for people who are predisposed to schizophrenia, and may worsen the symptoms of other mental illnesses." Another noticeable change was the large increase in use of cannabis among older adults. Use by those aged 50 years and older increased more than 3-fold from 1.4% to 4.7% between 1996 and 2009 and, among past year cannabis users, the proportion of users aged 50 years and older increased from 1.9% to 13.9% during the same time period.

Tobacco:- Some positive findings are that the percentage of adult Ontarians reporting smoking cigarettes declined from 19.7% in 2008 to 18.6% in 2009. Though 14% of Ontarians still report daily smoking, it is a positive sign that cigarette smoking has steadily declined since 1996, from 26.8% to 18.6% in 2009. Dr. Mann notes that the provincial government's commitment to anti- smoking legislation through smoke-free Ontario probably played an important role in the decrease in smoking rates.

Mental Health:- One in seven Ontario adults (14.7%), representing 1,400,000 people, reported symptoms of elevated psychological distress, and almost 6% reported that their overall mental health was poor. Those aged 30-39 were the most likely to report poor mental health, and those over age 65 reported the lowest rates of poor mental health. Mental health was strongly correlated with education. Those who had not graduated high school reported higher levels of poor mental health, and those who had graduated from university reported lower rates. "These results suggest that the social determinants of health, such as income, play as important a role in mental health as they do in physical health," said Mann. The use of anti-anxiety medication has remained stable over the past few years, but trend data shows that over the past 10 years, use of these medications has risen from 4.5% to nearly 7% of Ontario adults. The same pattern can also be seen in the use of antidepressant medication, which has trended upward from 3.6% in 1999 to the current rate of 6.6%. Added Dr. Mann, "Though these are marked increases, they may also be showing that more people experiencing mental health problems are seeking and receiving help, which is a positive step." Despite several differences, there was no strong dominant pattern in regional differences. Those from Northern Ontario were the most likely to be current smokers and to smoke daily; those from Toronto were the least likely to drink alcohol; those from the South West region of the province reported the highest average number of drinks consumed per week; and driving after drinking was most likely in the South West and in the Central South regions. Provided by Centre for Addiction and Mental Health: "Drinking, cannabis use and psychological distress increase, CAMH survey finds." June 13th, 2011. 

http://medicalxpress.com/news/2011-06-cannabis-psychological-distress-camh-survey.html

How cannabis causes 'cognitive chaos' in the brain

October 25th, 2011 in Neuroscience 

Cannabis use is associated with disturbances in concentration and memory. New research by neuroscientists at the University of Bristol, published in the Journal of Neuroscience, has found that brain activity becomes uncoordinated and inaccurate during these altered states of mind, leading to neurophysiological and behavioural impairments reminiscent of those seen in schizophrenia.

The collaborative study, led by Dr Matt Jones from the University's School of Physiology and Pharmacology, tested whether the detrimental effects of cannabis on memory and cognition could be the result of 'disorchestrated' brain networks.

Brain activity can be compared to performance of a philharmonic orchestra in which string, brass, woodwind and percussion sections are coupled together in rhythms dictated by the conductor. Similarly, specific structures in the brain tune in to one another at defined frequencies: their rhythmic activity gives rise to brain waves, and the tuning of these brain waves normally allows processing of information used to guide our behaviour.

Using state-of-the-art technology, the researchers measured electrical activity from hundreds of neurons in rats that were given a drug that mimics the psychoactive ingredient of marijuana. While the effects of the drug on individual brain regions were subtle, the drug completely disrupted co-ordinated brain waves across the hippocampus and prefrontal cortex, as though two sections of the orchestra were playing out of synch.

Both these brain structures are essential for memory and decision-making and heavily implicated in the pathology of schizophrenia.

The results from the study show that as a consequence of this decoupling of hippocampus and prefrontal cortex, the rats became unable to make accurate decisions when navigating around a maze.

Dr Jones, lead author and MRC Senior Non-clinical Fellow at the University, said: "Marijuana abuse is common among sufferers of schizophrenia and recent studies have shown that the psychoactive ingredient of marijuana can induce some symptoms of schizophrenia in healthy volunteers. These findings are therefore important for our understanding of psychiatric diseases, which may arise as a consequence of 'disorchestrated brains' and could be treated by re-tuning brain activity."

Michal Kucewicz, first author on the study, added: "These results are an important step forward in our understanding of how rhythmic activity in the brain underlies thought processes in health and disease."

Provided by University of Bristol

"How cannabis causes 'cognitive chaos' in the brain." October 25th, 2011. 
http://medicalxpress.com/news/2011-10-cannabis-cognitive-chaos-brain.html

Cannabis harms the brain - but that's not the full story

December 12th, 2011 in Psychology & Psychiatry 

(Medical Xpress) -- For the first time, scientists have proven that cannabis harms the brain. But the same study challenges previously-held assumptions about use of the drug, showing that some brain irregularities predate drug use. 

Professor Dan Lubman, from Turning Point Alcohol and Drug Centre and Monash University, along with a team of researchers from Melbourne University have conducted a world-first study examining whether these brain abnormalities represent markers of vulnerability to cannabis use.

“Previous evidence has shown that long-term heavy cannabis use is associated with alterations in regional brain volumes,” Professor Lubman said.

“Although these changes are frequently attributed to the neurotoxic effects of cannabis, no studies have examined whether structural brain abnormalities are present before the onset of cannabis use until now.”

To fill this void in present studies, Professor Lubman and his team recruited participants from primary schools in Melbourne, Australia, as part of a larger study examining adolescent emotional development.

Of the 155 original participants who underwent structural magnetic resonance imaging at age 12, 121 completed a follow-up survey measuring substance use four years later. It was found that by age 16, 28 participants had commenced using cannabis.

“This is an important developmental period to examine, because although not all individuals who initiate cannabis use during this time will go on to use heavily, early cannabis use has been associated with a range of negative outcomes later in life,” Professor Lubman said.

Their findings revealed that youth with smaller orbitofrontal cortex (OFC) volumes, part of the frontal lobe of the brain, at age 12 were more likely to have initiated cannabis use by age 16. The volumes of other regions of the brain did not predict later cannabis use.

“Given the lack of research in this area, we hypothesised that pre-drug use differences would be consistent with the structural abnormalities that have been found in studies of heavy users,” Professor Lubman said.

“What we found is that only the OFC predicted later cannabis use, suggesting that this particular part of the frontal lobe increases an adolescent’s vulnerability to cannabis use. However, we also found no differences in brain volume in other parts of the brain that we have shown to be abnormal in long-term heavy cannabis users, confirming for the first time, that cannabis use is neurotoxic to these brain areas in humans.” The OFC plays a primary role in inhibitory control and reward-based decision making; previous studies of adolescent cannabis users have demonstrated subtle deficits in problem-solving, attention, memory and executive functions. “In adult cannabis users, decreased activation of the OFC has been associated with faulty decision-making, suggesting that a reduced ability to weigh the pros and costs of one’s actions might render certain individuals more prone to drug problems,” Professor Lubman said. “These results have important implications for understanding neurobiological predictors of cannabis use, but further research is still needed to understand their relationships with heavier patterns of use in adulthood as well as later abuse of other substances.” 

This research has been published online in Biological Psychiatry, the official journal of the Society of Biological Psychiatry. Provided by Monash University "Cannabis harms the brain - but that's not the full story." December 12th, 2011. http://medicalxpress.com/news/2011-12-cannabis-brain-full-story.html

'Don't do drugs!' Man with half a head explains how he got bizarre injury after crashing car while stoned

·         Carlos 'Halfy' Rodriguez lost a large portion of his brain and skull after flying through his car's windscreen and landing on his head

·         Speaking out for the first time, many thought that his appearance was fake - until now

·         'That is why it is not good drinking and driving, or drugs and driving. It is no good kids,' he warns.

·         But despite his anti-drugs stance it appears he still continues to smoke cannabis every day

By Martin Robinson

Last updated at 12:41 PM on 17th February 2012

A bad boy who was left with half a head following a dramatic accident has spoken out for the first time - blaming his astonishing appearance on a drink and drugs binge.

Carlos 'Halfy' Rodriguez, who also goes by the name Sosa, lost a large portion of his brain and skull in a crash after flying through his car's windscreen and landing head-first on the road.

In a new video he has used his appearance and story to warn others not to drink and take drugs.

Doctors were forced to cut away large amounts of flesh and bone to help him survive and he has since been able to continue his life in Miami, Florida.

WARNING GRAPHIC CONTENT: SCROLL DOWN FOR VIDEO

Incredible: From side on the damage caused by his crash is obvious

Both sides: 'Halfy' as he is now known, shows his skull to camera in this new video

Warning: Carlos admits that he was on drink and drugs while driving and warns others not to do the same

From the front: Carlos speaks to camera for the first time and from this angle the damage to his head is not clear

'I was barred out on drugs. I was driving and I hit a pole and flew out the front window and landed on my head,' he said in a new warning message on You Tube.

Showing his head to camera he added: 'And this is how the old boy has come out. That is why it is not good drinking and driving or drugness (sic) and driving. It is no good kids.'

According to the German tabloid Bild he had the accident aged 14.

'I was with a cousin and a friend stole the car, there was a near-fatal car accident. As the speed was too fast we lost control of the car and crashed,' he said.

Mr Rodriguez shot to fame two years ago after he was was arrested for allegedly soliciting prostitution.

Miami Police had problems with their paperwork and his forms contained no name and simply the description 'half a head'.  

Infamous: Police released these mind-bending mugshots 18 months ago, and many believed them fake

His mugshots, showing his missing forehead and battered skull, spread across the world online but many thought that it was a hoax.

However this new video has proved that he and his extreme injuries exist.

Bad boy: 'Halfy' still smokes drugs, despite his warning to others

But despite his serious message to stay away from narcotics, it appears that he is yet to change his ways after admitting he still smokes a lot of drugs.

Survivor: British teenager Ben Maycock was lucky to be alive after a brutal hammer attack left him a huge dent in his skull

In a bizarre tirade he also accuses American President Barrack Obama of doing the same.

'This is what I do daily: burn a stake,' which is slang for a joint.

'Obama is the President of ya'll United States and he smokes. (Expletive) has the whole White House growing.

'Then why can't I smoke me a blunt?'.

'Halfy' is not the only person to survive with half a head, as several other Britons have done the same.

Teenager Ben Maycock was lucky to be alive after a brutal hammer attack left him a huge dent in his skull in 2010.

The vicious assault left Ben's head shattered - and doctors had to hack away huge chunks in a battle to save his life.

Medics at Queen's Medical Centre, Nottingham, doubted Ben would survive his horrific injuries, and told his grief-stricken mum to prepare for the worst, but incredibly, he survived.

Video at the website
Read more: http://www.dailymail.co.uk/news/article-2102461/Man-half-head-Carlos-Halfy-Rodriguez-explains-got-bizarre-injury.html#ixzz1msTTvNo0

Scientists find anticonvulsant drug helps marijuana smokers kick the habit

April 24th, 2012 in Addiction 

Scientists at The Scripps Research Institute have found clinical evidence that the drug gabapentin, currently on the market to treat neuropathic pain and epilepsy, helps people to quit smoking marijuana (cannabis). Unlike traditional addiction treatments, gabapentin targets stress systems in the brain that are activated by drug withdrawal.

In a 12-week trial of 50 treatment-seeking cannabis users, those who took gabapentin used less cannabis, experienced fewer withdrawal symptoms such as sleeplessness, and scored higher on tests of attention, impulse-control, and other cognitive skills, compared to patients who received a placebo. If these results are confirmed by ongoing larger trials, gabapentin could become the first FDA-approved pharmaceutical treatment for cannabis dependence. "A lot of other drugs have been tested for their ability to decrease cannabis use and withdrawal, but this is the first to show these key effects in a controlled treatment study," said Barbara J. Mason, the Pearson Family Chair and Co-Director of the Pearson Center for Alcoholism and Addiction Research at Scripps Research. "The other nice thing about gabapentin is that it is already widely prescribed, so its safety is less likely to be an issue." Mason led the new gabapentin study, recently published online ahead of print by the journal Neuropsychopharmacology.

Stress Circuits

Addiction researchers have long known that recreational drugs hook users by disrupting the normal tuning of their brains' reward and motivation circuitry. But as scientists at Scripps Research and other institutions have shown in animal studies, cannabis withdrawal after prolonged heavy use also leads to the long-term activation of basic stress circuits. "In human cannabis users who try to quit, this stress response is reflected in reports of drug craving, sleep disturbances, anxiety, irritability, and dysphoria, any one of which can motivate a person to return to using, because cannabis will quiet these symptoms," said Mason.

A 2008 study by Pearson Center Co-Director George Koob and his colleagues found that gabapentin, an FDA-approved anticonvulsant drug that resembles the neurotransmitter GABA, can quiet this withdrawal-related activation in stress circuitry in alcohol-dependent rats. That finding motivated Mason to set up a pilot trial of gabapentin in cannabis-dependent individuals, whose withdrawal syndrome features a similar over-activation of stress circuits. She and her colleagues recruited cannabis users with local newspaper and web ads headlined: "Smoking too much pot? We want to help you stop." "We needed only 50 subjects, but we quickly got more than 700 queries from cannabis users who were eager to quit," Mason said. "Some people deny that cannabis can be addictive, but surveys show that between 16 and 25 percent of substance use treatment admissions around the world every year involve people with primary cannabis dependence."

Twice as Many Abstinent from Cannabis Use

The trial was based at Mason's laboratory at The Scripps Research Institute. Half of the 50 recruits were randomly assigned to take 1,200 mg/day of gabapentin; the rest were given identical-looking placebo capsules. Over 12 weeks, Mason and her colleagues, including a medical team from the nearby Scripps Clinic, monitored the subjects with tests. Using standard behavioral therapy techniques, they also counseled the patients to stay off cannabis. The subjects' self-reports and more objective urine tests revealed that gabapentin, compared to placebo, significantly reduced their continuing cannabis use. "Urine metabolite readings indicate about twice as many of the gabapentin subjects had no new cannabis use during the entire study, and, in the last four weeks of the study, all of the gabapentin subjects who completed the study stayed abstinent," Mason said. Gabapentin also clearly reduced the reported symptoms of withdrawal such as sleep disturbances, drug cravings, and dysphoria. And even though gabapentin normally is thought of as a brain-quieting drug that can cause sleepiness as a side effect, there was some evidence that it sharpened cognition among the cannabis users. Seven gabapentin and ten placebo patients sat for tests of attention, impulse-control, and other executive functions just before the start of the trial and at week four. While the placebo patients tended to score lower after four weeks of attempted abstinence, the gabapentin patients generally scored higher.

Help Resisting Cravings

Addiction researchers now recognize that one of the effects of repeated drug use is the weakening of executive functions—which can happen through the over-activation of reward circuitry as well as by withdrawal-related stress. "That weakening of self-control-related circuits makes it even harder for people to resist drug cravings when they're trying to quit, but gabapentin may help restore those circuits, by reducing stress and enabling patients to sleep better, so that they function better while awake," Mason said. She is now conducting a larger, confirmatory study of gabapentin in cannabis users, as well as a new study of a novel drug that targets the same stress circuitry. "People in the treatment community have told me that they're eager for these trial results to come out, because until now nothing has been shown to work against both relapse and withdrawal symptoms," Mason said. More information: "A Proof-of-Concept Randomized Controlled Study of Gabapentin: Effects on Cannabis Use, Withdrawal and Executive Function Deficits in Cannabis-Dependent Adults", Neuropsychopharmacology.

Provided by The Scripps Research Institute "Scientists find anticonvulsant drug helps marijuana smokers kick the habit." April 24th, 

2012. http://medicalxpress.com/news/2012-04-scientists-anticonvulsant-drug-marijuana-smokers.html

Study shows how cannabis use during adolescence affects brain regions associated with schizophrenia - May 8th, 2012 in Neuroscience

New research from the Royal College of Surgeons in Ireland (RCSI) published in Nature's Neuropsychopharmacology has shown physical changes to exist in specific brain areas implicated in schizophrenia following the use of cannabis during adolescence. The research has shown how cannabis use during adolescence can interact with a gene, called the COMT gene, to cause physical changes in the brain.

The COMT gene provides instructions for making enzymes which breakdown a specific chemical messenger called dopamine. Dopamine is a neurotransmitter that helps conduct signals from one nerve cell to another, particularly in the brains reward and pleasure centres. Adolescent cannabis use and its interaction with particular forms of the COMT gene have been shown to cause physical changes in the brain as well as increasing the risk of developing schizophrenia.

Dr Áine Behan, Department of Physiology, RCSI and lead author on the study said 'This is the first study to show that the combined effects of the COMT gene with adolescent cannabis use cause physical changes in the brain regions associated with schizophrenia. It demonstrates how genetic, developmental and environmental factors interact to modulate brain function in schizophrenia and supports previous behavioural research which has shown the COMT gene to influence the effects of adolescent cannabis use on schizophrenia-related behaviour's.

The three areas of the brain assessed in this study were found to show changes in cell size, density and protein levels.

'Increased knowledge on the effects of cannabis on the brain is critical to understanding youth mental health both in terms of psychological and psychiatric well-being,' Dr Behan continued.

The research was funded by the Health Research Board and Science Foundation Ireland.

Provided by Royal College of Surgeons in Ireland

"Study shows how cannabis use during adolescence affects brain regions associated with schizophrenia." May 8th, 2012. 
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Study: Adolescent marijuana use leaves lasting mental deficits

August 27th, 2012 in Psychology & Psychiatry 

The persistent, dependent use of marijuana before age 18 has been shown to cause lasting harm to a person's intelligence, attention and memory, according to an international research team.

Among a long-range study cohort of more than 1,000 New Zealanders, individuals who started using cannabis in adolescence and used it for years afterward showed an average decline in IQ of 8 points when their age 13 and age 38 IQ tests were compared. Quitting pot did not appear to reverse the loss either, said lead researcher Madeline Meier, a post-doctoral researcher at Duke University. The results appear online Aug. 27 in PNAS. The key variable in this is the age of onset for marijuana use and the brain's development, Meier said. Study subjects who didn't take up pot until they were adults with fully-formed brains did not show similar mental declines. Before age 18, however, the brain is still being organized and remodeled to become more efficient, she said, and may be more vulnerable to damage from drugs.

"Marijuana is not harmless, particularly for adolescents," said Meier, who produced this finding from the long term Dunedin Multidisciplinary Health and Development Study. The study has followed a group of 1,037 children born in 1972-73 in Dunedin, New Zealand from birth to age 38 and is led by Terrie Moffitt and Avshalom Caspi, psychologists who hold dual appointments at Duke and the Institute of Psychiatry at King's College London. About 5 percent of the study group were considered marijuana-dependent, or were using more than once a week before age 18. A dependent user is one who keeps using despite significant health, social or family problems.

At age 38, all of the study participants were given a battery of psychological tests to assess memory, processing speed, reasoning and visual processing. The people who used pot persistently as teens scored significantly worse on most of the tests. Friends and relatives routinely interviewed as part of the study were more likely to report that the persistent cannabis users had attention and memory problems such as losing focus and forgetting to do tasks. The decline in IQ among persistent cannabis users could not be explained by alcohol or other drug use or by having less education, Moffitt said.

While 8 IQ points may not sound like a lot on a scale where 100 is the mean, a loss from an IQ of 100 to 92 represents a drop from being in the 50th percentile to being in the 29th, Meier said. Higher IQ correlates with higher education and income, better health and a longer life, she said. "Somebody who loses 8 IQ points as an adolescent may be disadvantaged compared to their same-age peers for years to come," Meier said.

Laurence Steinberg, a Temple University psychologist who was not involved in the research, said this study is among the first to distinguish between cognitive problems the person might have had before taking up marijuana, and those that were apparently caused by the drug. This is consistent with what has been found in animal studies, Steinberg added, but it has been difficult to measure in humans.

Animal studies involving nicotine, alcohol and cocaine have shown that chronic exposures before the brain is fully developed can lead to more dependence and long-term changes in the brain. "This study points to adolescence as a time of heightened vulnerability," Steinberg said. "The findings are pretty clear that it is not simply chronic use that causes deficits, but chronic use with adolescent onset."

What isn't possible to know from this study is what a safer age for persistent use might be, or what dosage level causes the damage, Meier said. After many years of decline among US teens, daily marijuana use has been seen to increase slightly in the last few years, she added. Last year, for the first time, US teens were more likely to be smoking pot than tobacco. "The simple message is that substance use is not healthy for kids," Avshalom Caspi said via email from London. "That's true for tobacco, alcohol, and apparently for cannabis."

More information: "Persistent Cannabis Users Show Neuropsychological Decline From Childhood to Midlife," Madeline H. Meier, Avshalom Caspi, et al. Proceedings of the National Academy of Sciences, Online Early Edition, Monday, Aug. 27, 2012.

Provided by Duke University

"Study: Adolescent marijuana use leaves lasting mental deficits." August 27th, 2012. 
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Heavy teenage cannabis use linked with anxiety disorders

August 8th, 2012 in Addiction 

(Medical Xpress) -- Teenagers who smoke cannabis weekly or more are twice as likely as non-users to have an anxiety disorder in their late 20s, even if they stop using, a study of 2000 Victorian teenagers has found.

Those who used frequently in their teens and continued to use on a daily basis at the age of 29 were three times as likely to have an anxiety disorder compared with non- or infrequent users. Those who used minimally in their teens but became daily users in their late 20s were two and a half times as likely to have an anxiety disorder.

But the really striking finding say the authors is the persistent association between frequent teenage cannabis use and adult anxiety disorders up to a decade after cannabis use has ceased.

The relationship between cannabis use and anxiety disorders was present even after the researchers took into account other possible explanations such as mental health problems in their teens or other drug use in their twenties.

The findings, published online in Addiction are based on secondary analyses of a landmark study of nearly 2000 Victorian secondary school students - the 2000 stories cohort, led by Professor George Patton of the Centre for Adolescent Health at the Murdoch Childrens Research Institute in Melbourne. The students have been followed up and interviewed over 13 years, starting in 1992. They were interviewed at six six-monthly intervals during their teens and then again when they were aged 20-21, 24-25, and 29. Lead author of the analysis, Professor Louisa Degenhardt from the National Drug and Alcohol Research Centre at the University of New South Wales, said that most studies looking at cannabis use and mental health outcomes focus on adolescence and early adulthood. “What we are seeing is a persistent association with anxiety disorders over a much longer period.

“Given that anxiety is the most prevalent mental health disorder in the Australian population, affecting over 14 per cent of adults in any 12 month period, we need to investigate the findings further because it is highly possible that early cannabis use causes enduring mental health risks.”

Professor Patton, lead investigator of the 2000 stories cohort, said that the findings could be explained by lasting changes to brain function caused by introducing cannabis at a time when the brain is developing rapidly. Equally it could be that the very factors which predispose people to use cannabis early also predispose them to common mental health problems.

“We know from animal studies that introducing cannabis during puberty brings about long lasting changes in behaviour which persist even after administration of cannabis is stopped. These findings suggest that a similar thing may be happening,” said Professor Patton.  “During the teen years the parts of the brain that are involved in managing emotions are still developing rapidly and it is highly possible that heavy cannabis use at this sensitive point could have long lasting effects.”

However the authors write that they cannot rule out the possibility that the factors that predispose people to use cannabis early also put them at risk for common mental disorders.  “These common factors might include biological, personality, social and environmental factors, or a combination of these factors. This is a plausible hypothesis because social disadvantage is more common among persons who are problematic substance users and who meet criteria for common mental disorders,” they write.

More information: onlinelibrary.wile… .04015.x/pdf

Provided by University of New South Wales

"Heavy teenage cannabis use linked with anxiety disorders." August 8th, 2012. http://medicalxpress.com/news/2012-08-heavy-teenage-cannabis-linked-anxiety.html