Anxiety sensitivity and cannabis use

Anxiety sensitivity can be defined as being anxious about being anxious. People with anxiety sensitivity are anxious about the physical symptoms of being anxious (an upset tummy, sweaty palms, pounding heart), mental incapacitation (losing control and not being able to think properly) and social concerns such as other people seeing them with a red face or in a panic. Some researchers think anxiety sensitivity plays a part in cannabis use and a team of researchers led by Julia D. Buckner from Louisiana State University looked into this in a study of 49 current cannabis users who were asked to fill in assessments about their mood at random times over a two-week period. The researchers found that at the start of the study fears about mental incapacitation were significantly related to more severe cannabis problems. Over the course of the study fears about mental incapacitation and social concerns were linked to subsequent cannabis use.

Buckner, Julia D. ... [et al] - Anxiety sensitivity and marijuana use: an analysis from ecological momentary assessment Depression and Anxiety DOI 10.1002/da.20816

Cannabis use and psychosis

Much research has been devoted to the links between cannabis use and psychosis and a team of researchers from Maastricht University in the Netherlands has added to the evidence to suggest that there is a link. The researchers studied 1,923 people who were aged between 14 and 24 at the start of the study. They were asked about their cannabis use and assessed for psychosis symptoms at the start of the study (T1), 3.5 years later (T2) and 8.4 years later (T3). The researchers found that people who hadn't used cannabis at the start of the study but who used it between T1 and T2 had nearly twice the risk of developing psychosis symptoms by the end of the study. If they carried on using cannabis between T2 and the end of the study their risk was 2.2 times greater. By the end of the study the incidence rate of psychosis symptoms was 14% in those who had smoked cannabis compared to only 8% in those who hadn't.

Kuepper, Rebecca ... [et al] - Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study British Medical Journal doi: 10.1136/bmj.d738

U.S. anti-drugs campaign shows early promise

In 2005 the U.S. Office of National Drug Control Policy launched its Above the Influence campaign - funded at a cost of $200m a year - which aimed to prevent teenagers from using cannabis. Unlike previous campaigns, which stressed the risks of the drug, Above the Influence stressed how cannabis could prevent teenagers reaching their own goals and compromise their independence and used the slogan "Getting messed up is just another way of leaving yourself behind." Researchers from Ohio State University studied 3,236 children who were around 12 when the study began in 2005. They were surveyed four times beginning in Year Seven and ending about a year and a half later. Up to 79% of children said they had seen the campaign ads. Only 8% of the students who had seen the ads started using cannabis, compared to 12% of those who hadn't. The results are an encouraging first step but the children will need to be followed up for longer to reach a definitive verdict on the success, or otherwise, of the campaign.

Cannabis use and psychosis

The extent and nature of the link between cannabis use and psychosis is one of the most controversial areas of psychiatry. A team of researchers, led by Matthew Large from the Prince of Wales Hospital in New South Wales reviewed 83 studies into the relationship between cannabis use and the age at which people become ill with psychosis. They found that people who used cannabis became ill, on average, 2.7 years earlier than those who didn't with people who used any illegal drugs becoming ill 2 years earlier. Alcohol use was not associated with an earlier onset of psychosis.

Large, Matthew - Cannabis use and earlier onset of psychosis Archives of General Psychiatry
doi:10.1001/archgenpsychiatry.2011.5

Jailed parents raise children's drug risk

The prison population of the U.S. has grown from 250,000 in the mid-1970s to about 2.25 million today and it is now estimated that one in eight youngsters in the U.S.  has a father who has done time. Children of fathers who have been in prison are known to be at a greater risk of developing mental-health problems, becoming prisoners themselves, dropping out of high school and being poor and a new study suggests - perhaps hardly surprisingly - that they are at a greater risk of developing drug problems too. Michael E. Roettger, formerly of Bowling Green State University in Ohio and now at the University of Colorado in Boulder looked at data from 150,000 young men and women followed from adolescence into early adulthood as part of the National Longitudinal Study of Adolescent Health. Half of the young men and 39% of the young women whose fathers had been in jail reported using cannabis compared to 38% and 28% respectively of young people whose fathers had not been imprisoned. Those whose fathers had served time also used the drug more frequently and longer into adulthood. One out of every four young men whose fathers had been in prison had used harder drugs such as cocaine and methamphetamine - double the rate of other youngsters. While only 4% of white children have a parent who has been in jail one in four African-American children do so.

Childhood trauma, cannabis use and psychosis

Although it is still a controversial topic some research has shown that using cannabis in adolescence is associated with an increased risk of developing psychosis. At the same time suffering childhood trauma is associated both with an increased risk of substance misuse and of developing psychosis. A team of Irish researchers tried to get to the bottom of the links between childhood trauma, substance abuse and psychosis in a study of 211 children aged between 12 and 15. They were asked about childhood trauma, cannabis use and any mental-health problems they might be having. The researchers found that both childhood trauma and cannabis use were significantly associated with an increased risk of developing psychosis symptoms. However, the presence of both childhood trauma and early cannabis use significantly increased the risk for psychotic symptoms beyond the risk posed by either factor alone.

Harley, M. ... [et al] - Cannabis use and childhood trauma interact additively to increase the risk of psychotic symptoms in adolescence Psychological Medicine, October 2010, 40(10), 1627-1634

Cannabis and other drugs. Is the gateway closing?

Opponents of the legalisation of cannabis often suggest that it is a 'gateway' drug from which people move on to more damaging substances such as heroin or cocaine. However, new research from the University of New Hampshire has called this idea into question. The researchers used information from surveys of 1,286 youngsters carried out in the Miami area in the 1990s. The study found that teenagers who did not graduate from high school or go to college were more likely to have used cannabis as teenagers and other illegal drugs as young adults. However, once the effect of unemployment was taken into account the 'gateway effect' diminished; in other words once people had got a job they were much less likely to move on from cannabis to a more harmful drug. Once the young adults had reached the age of 21 the gateway effect had subsided completely. The strongest predictor of people moving on to other drugs was race with White people being more at risk of doing so than people of Hispanic or African descent.

You can find out more about this research by clicking on the title of this post.

Alcohol and cannabis - the earlier they start the harder they fall

Alcohol and cannabis are the most commonly used substances among adults and teenagers in the U.S. and other developed countries. One survey showed that 41, 62 and 73% of Year 8, 10 and 12 students respectively had drunk alcohol with the figures for cannabis smoking for the same years being 16, 32 and 42%. Many programmes for preventing teenage alcohol and drug use aim to delay the age at which people first start using these substances with the hope that this will prevent problems in adolescence and adulthood. However, few long-term studies have followed people from early adolescence to young adulthood in order to examine the effects of early drug and alcohol use. Researchers from Weill Cornell Medical College in New York followed 621 people from Year 7 to Year 12 asking them about their drug and alcohol use and then got them to fill out a survey about their lives at 24. The study found that an early start to substance use was linked to a higher incidence of weekly alcohol use in young adulthood as well as more substance-related occupational,relationship and legal problems. The majority of young adults with problems due to alcohol or drug use had first reported having alcohol and cannabis before Year 12. The negative effects of early-onset substance use were strongest in people's social and work lives.

Griffin, K.W., Bang, H. and Botvin, G.J. - Age of alcohol and marijuana use onset predicts weekly substance use and related psychosocial problems during young adulthood. Journal of Substance Use, June 2010, 15(3), 174-183

Cannabis and schizophrenia - new evidence to add to the debate

Much ink has been spilt and many trees sacrificed debating the links between smoking cannabis and schizophrenia. Researchers from Stony Brook University in New York have added to the debate with a long-term study following 229 patients for ten years after they were first admitted to a psychiatric hospital. They compared the patients' use of marijuana - both recently and over their lifetimes - with how old they were when their symptoms started and how severe those symptoms currently were. Two-thirds of the participants had smoked cannabis at some point in their lives. The people who had used cannabis before being hospitalised had worse symptoms of psychosis than those who hadn't and were admitted at a younger age. Patients whose symptoms had become worse said they were smoking more cannabis next time they were interviewed and people who started smoking more cannabis developed worse symptoms.

You can find out more about this research at

http://uk.reuters.com/article/idUKTRE65150620100602?feedType=RSS&feedName=healthNews

Sleep, spliffs and social networks

Recent studies have found that obesity, smoking and altruism can all spread through social networks, affecting not just our friends but their friends too. Now researchers from the University of California, San Diego and Harvard University have found that poor sleep and drug use can also spread through social networks. They studied 8,349 adolescents between year 7 and year 12 and found clusters of poor sleep and cannabis (marijuana) use that extended up to four degrees of separation within social networks. The researchers also found that it was the poor sleep that led on to cannabis use not vice versa.

You can find out more about this research at

http://psychcentral.com/news/2010/03/22/sleep-loss-tied-to-drug-use-in-teen-social-networks/12286.html

Early cannabis use and psychosis

The link between cannabis use and psychosis is a controversial topic and research into it has often generated more heat than light. The latest study comes from the University of Queensland and involved more than 3,800 21-year-olds. It found that those who had begun using cannabis very early (six or more years before they were 21) were three times more likely to suffer from psychiatric symptoms. Another study of 228 siblings carried out by the same researchers also found a link between early cannabis use and psychosis.

You can find out more about this research at

http://www.medicalnewstoday.com/articles/181118.php

Cannabis and suicide risk

Smoking cannabis is unlikely to increase your risk of killing yourself. Researchers from Cardiff University looked at data on more than 50,000 Swedish military recruits. Sweden has conscription and the study covered 50,087 men and women who were conscripted between 1969 and 1970 when they were aged between 18 and 20. Over the next 30 years 600 of the sample killed themselves. Those who admitted to smoking cannabis when they were conscripted were 62% more likely to kill themselves during the follow-up period. However, once other factors such as childhood behaviour problems, psychological adjustment, mental-health problems, drinking, smoking and parental drug use were taken into account the link between cannabis use and suicide disappeared.

You can find out more about this study at

http://uk.reuters.com/article/idUKTRE60E3CB20100115?feedType=RSS&feedName=healthNews

Thrill-seeking, disruptive behaviour and cannabis use

High-intensity pleasure seeking refers to a tendency in teenagers to look for physical and social thrills. Broadly speaking it's what makes some kids go for raves and snowboarding while others go for hanging around in shopping centres and watching TV. A team of researchers from the Erasmus Medical Centre in Rotterdam looked into the links between high-intensity pleasure seeking, disruptive behaviour and the early onset of cannabis use. They found that both early-adolescent high-intensity pleasure seeking and disruptive behaviour (naughtiness and attention-deficity hyperactivity disorder (ADHD)) were linked to an early start smoking cannabis. However, there was little interaction between the two factors suggesting that thrill-seeking and disruptive behaviour lead on to cannabis use by different 'pathways.'

Creemers, Hanneke E. ... [et al] - Predicting onset of cannabis use in early adolescence: the interrelation between high-intensity pleasure and disruptive behavior: the TRAILS study Journal of Studies on Alcohol and Drugs November 2009, 70(6), 850-858

Daily cannabis use and psychosis risk

People who increase their cannabis consumption from occasional to daily use could hasten the onset of psychosis. Researchers from Emory University in Atlanta analyzed data from 109 hospitalized patients who were experiencing their first psychotic episode and found that those who had a history of cannabis use and increased to daily smoking experienced both psychotic and pre-psychotic symptoms at earlier ages. It was not whether or not they used the drug in adolescence but how quickly they moved on to daily use that was the main risk factor for developing the condition. The women who moved on to daily pot smoking had a greater increased risk for the onset of psychosis than the men.

You can find out more about this research at

http://www.sciencedaily.com/releases/2009/12/091220144936.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Twins, genes and cannabis and alcohol dependence

The genes that predispose people to become addicted to alcohol could also play a part in cannabis dependence. Roughly 8-12% of cannabis users are considered to be dependent and, just like alcohol, the severity of symptoms increases with heavier use. A survey of Year 12 students in 2008 found that 5.4% of them had used cannabis daily in the last month. Researchers from Washington University School of Medicine studied 6,257 people in Australia. The participants in the study were all on the Australian twin registry and were made up of 2,761 pairs of twins and 735 singletons. The findings of the study showed that many of the same genetic factors that contributed to alcohol use also contributed to marijuana use and alcohol and cannabis dependence could also be traced to some of the same genetic influences.

You can find out more about this research at

http://www.medicalnewstoday.com/articles/174570.php

Cannabis and suicide

Although cannabis has been linked to psychosis (see below) there is not such good evidence linking it to depression, anxiety and thoughts of suicide. Researchers from Cardiff and Bristol universities and the Karolinska Institute in Stockholm studied 50,087 men conscripted for military service in Sweden and compared the records from their army medicals with suicides recorded on the National Cause of Death Register over the next 33 years. There were 600 suicides among the group over the next 33 years with cannabis increasing the risk by 62%. However, the link between cannabis and suicide disappeared once the researchers took into account other factors. These included: having a low IQ, drinking heavily, having parents with mental-health problems, smoking heavily, using other drugs, having a psychiatric diagnosis when conscripted, having a 'high problematic behaviour score', 'poor psychological adjustment' and poor social relations.

Price, Ceri ... [et al] - Cannabis and suicide: longitudinal study British Journal of Psychiatry December 2009, 195(6), 492-497

Skunk and psychosis

There has been a lot of debate about the links between cannabis and psychosis and in particular the effects of high-strength 'skunk' cannabis which contains much more of the active ingredient delta-9-tetrahydrocannabinol. Researchers from the Institute of Psychiatry, King's College London compared 280 people turning up for treatment with their first episode of psychosis with 174 healthy people recruited from the local population. There was no difference between the two groups in terms of whether they had ever taken cannabis but people with psychosis were over six times more likely to be current daily users of cannabis and over twice as likely to have smoked cannabis for more than five years. 78% of the people with psychosis smoked skunk compared to only 37% of the control group.

Di Forti, Marta ... [et al] - High-potency cannabis and the risk of psychosis British Journal of Psychiatry December 2009, 195(6), 488-491

Monitoring and marijuana

More than 42% of high-school students in the U.S. admit to taking cannabis. Apart from the risk of a criminal record cannabis use has also been linked to depression, cognitive impairment, cardiovascular disease and cancer. Parental monitoring - parents knowing where their children are, who they are with and what they are doing - has been associated with a reduced risk of gambling, sexual activity and drug use but the strength of the relationship between monitoring and cannabis use is unclear. Researchers from Claremont Graduate University in California reviewed 17 studies into this issue which covered a total of 35,000 participants. The review found that there was a 'strong, reliable' link between parental monitoring and decreased cannabis use and that this link was especially strong for girls.

You can find out more about this research at

http://www.sciencedaily.com/releases/2009/11/091116143623.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Cannabis and schizophrenia: has the U.K. Government over-reacted?

The idea that there is a link between cannabis and schizophrenia is a controversial one. Last year the U.K. Government reclassified cannabis as a class B drug, partly, at least, because they thought there was a link between the drug and mental illness. A study of the issue by researchers from the universities of Bristol and Cambridge and from the London School of Hygiene and Tropical Medicine has been looking into the risk and has estimated that to prevent one case of schizophrenia the Government would have to persuade 2,800 young men who are heavy users of cannabis to give up; a figure that rose to 5,000 for young women. For light users of cannabis these figures rose to 10,000 young men and 30,000 young women respectively.

You can find out more about this research at

http://www.sciencedaily.com/releases/2009/10/091022101538.htm

Cannabis and psychosis

Since the nineteenth century there have been descriptions of acute schizophrenia-like psychotic symptoms in healthy people who have taken cannabis. The prevalence of cannabis use in psychotic patients being treated for the first time is approximately double that found in the general population and those patients who carry on using cannabis have earlier and more frequent relapses compared to non users. Most of the effects of cannabis are due to a substance called delta-9-tetrahydrocannabinol (THC) but there are nearly 60 other chemicals from the same family in smoked cannabis and the variations in the quality of cannabis, the composition of joints and the physiology of smokers all make it hard to assess the effect of individual substances. Researchers from the Institute of Psychiatry in London used injections to deliver a standardised dose of 2.5mg of THC (about the same quantity as there is in an average joint) to 22 healthy men to see whether this would induce psychosis. The men were sometimes given an injection of a placebo for comparison purposes. The study found that THC did induce psychotic symptoms in previously-healthy men. THC also increased anxiety and affected neuropsychological performance but there was no relationship between the participants' levels of psychosis and their levels of anxiety or neuropsychological performance.

Morrison, P.D. ... [et al] - The acute effects of synthetic intravenous delta-9-tetrahydrocannabinol on psychosis, mood and cognitive functioning Psychological Medicine 39(10), 1607-1616