Teenage cannabis users are more vulnerable to heavy drug addiction and psychosis - and genes drive up the risks

These conclusions seem to reply on epidemiological reports -- which can be of dubious logic.  It could be that problem personalities are drawn to the drug rather than the drug damaging the personaity.  I have known cannabis users who seemed pretty spaced out whether they were high or not

Teenage brains may be especially vulnerable to the harmful effects of cannabis, experts believe.

The notion that cannabis is a 'safe' drug is misplaced and scientifically inaccurate, say researchers.  Scientists came to the conclusion after reviewing more than 120 studies looking at the effects of cannabis on the adolescent brain.

Professor Didier Jutras-Aswad, from the University of Montreal in Canada, who led the team, said: 'Data from epidemiological studies have repeatedly shown an association between cannabis use and subsequent addiction to heavy drugs and psychosis.

'Interestingly, the risk to develop such disorders after cannabis exposure is not the same for all individuals and is correlated with genetic factors, the intensity of cannabis use and the age at which it occurs.

'When the first exposure occurs in younger versus older adolescents, the impact of cannabis seems to be worse in regard to many outcomes such as mental health, education attainment, delinquency and ability to conform to adult role.'

Rat experiments had shown how cannabis targets areas of the brain linked to motivation, decision-making and habit-forming that change rapidly during the teenage years.

Taking the drug at this stage in life could greatly affect development of the brain and personality, according to the scientists writing in the journal Neuropharmacology.

'Of the illicit drugs, cannabis is most used by teenagers since it is perceived by many to be of little harm,' said Prof Jutras-Aswad.

'This perception has led to a growing number of states approving its legalisation and increased accessibility.

'Most of the debates and ensuing policies regarding cannabis were done without consideration of its impact on one of the most vulnerable population, namely teens, or without consideration of scientific data.

'While it is clear that more systematic scientific studies are needed to understand the long-term impact of adolescent cannabis exposure on brain and behaviour, the current evidence suggests that it has a far-reaching influence on adult addictive behaviours particularly for certain subsets of vulnerable individuals.'

Some people are genetically more susceptible than others to becoming dependent on cannabis, the research suggests.

In adolescent rats, scientists had observed individual differences in the chemical pathways that govern addiction and vulnerability.

This may help explain why around a quarter of teenager cannabis users end up abusing the drug or developing a dependency.

Studies also indicate that cannabis dependence can be inherited through certain genes passed by parents to their children.

Psychological influences are another important factor, say the researchers.

'Individuals who will develop cannabis dependence generally report a temperament characterised by negative affect, aggressivity and impulsivity, from an early age,' said Professor Jutras-Aswad.

'Some of these traits are often exacerbated with years of cannabis use, which suggests that users become trapped in a vicious cycle of self-medication, which in turn becomes a dependence.'
DNA Helix

Studies indicate that cannabis dependence can be inherited through certain genes passed by parents to their children. Psychological influences are also another important factor

He added: 'It is now clear from the scientific data that cannabis is not harmless to the adolescent brain, specifically those who are most vulnerable from a genetic or psychological standpoint.

'Identifying these vulnerable adolescents, including through genetic or psychological screening, may be critical for prevention and early intervention of addiction and psychiatric disorders related to cannabis use.

The objective is not to fuel the debate about whether cannabis is good or bad, but instead to identify those individuals who might most suffer from its deleterious effects and provide adequate measures to prevent this risk.'

'Continuing research should be performed to inform public policy in this area,' added co-author Dr Yasmin Hurd, from the Icahn School of Medicine at Mount Sinai, New York.

'Without such systematic, evidenced-based research to understand the long-term effects of cannabis on the developing brain, not only the legal status of cannabis will be determined on uncertain ground, but we will not be able to innovate effective treatments such as the medicinal use of cannabis plant components that might be beneficial for treating specific disorders.'

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Ketamine can relieve the symptoms of depression in more than 60% of patients - in as little as 24 hours

This was a rather small study of unknown representativeness so not much can be concluded at this stage. It could also be that side-effects make the cure worse than the disease

Ketamine could relieve the symptoms of depression in as little as 24 hours, new research suggests.  The drug, which is also used in anaesthesia, can relieve symptoms in more than 60 per cent of people with depression within 24 hours.

In contrast, most prescription anti-depressants take four to six weeks to prove effective.

The findings come after the biggest ever study to examine ketamine’s effect on depression.  Some 73 people with the condition were involved in the U.S. study, with two thirds given ketamine, and one third midazolam – a short-acting anaesthetic medication.

The researchers found that 64 per cent of those given ketamine improved within 24 hours.  In contrast, only 28 per cent of those given midazolam improved.

The research was carried out at the Michael E. DeBakey Veterans Affairs Medical Centre, Baylor College of Medicine in Houston, and the Icahn School of Medicine at Mount Sinai in New York,

Lead researcher, Dr Sanjay Mathew, said: ‘Through this study, we’ve now confirmed in an optimised trial design that ketamine does have robust and rapid antidepressant effects.’

Ketamine was given to the patients intravenously and in very low doses.

Dr Mathew explained: ‘All previous studies of ketamine have compared it to saline, an inert placebo without physical or psychological reactions.

‘The problem with this is that ketamine has usual side effects, such as feelings of floating, feelings of altered sense of time, maybe some blurred vision or some other physical or psychological symptoms.

‘Patients know that they received something active and the raters would know that as well, so the validity of the study may be in doubt with saline studies.

‘This is the first trial to compare ketamine to another drug that also has psychoactive properties.’

Dr Mathew and his colleagues followed the patients for seven days and found that many of the patients who received ketamine continued to benefit from the treatment after seven days, although there was a decrease in benefits by day seven.

They then studied the subgroup of patients who did well at day seven to see how long they remained depression-free and found that a small group of patients were able to remain depression-free for an additional four weeks.

Dr Mathew says that there is still much more that needs to be understood before ketamine can be used clinically.

For example, the best dose to use would have to be established and side effects, such as elevated blood pressure, would have to be taken into account.

The researchers believe that ketamine reduces depression by influencing the glutamate system – glutamate are neurotransmitters which speed up the transmission of information from one nerve cell to the next.

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