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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