Cannabis ... Risk to IQ

How teenagers addicted to cannabis risk damaging their IQ and show signs normally seen in early Alzheimer's

• Researchers put 1,000 boys and girls through a battery of IQ tests
• They did the same tests more than 20 years later, at the age of 38
• The study founda marked drop in intelligence and attention and memory were also harmed

By Fiona Macrae
PUBLISHED:21:07 GMT, 27 August 2012| UPDATED:15:54 GMT, 28 August 2012


Teenagers who become hooked on cannabis risk long-term damage to their IQ, researchers have warned.

A study found a marked drop in intelligence in those who started using the drug in their teens and continued to take it for years afterwards.

Attention and memory were also harmed, with those who developed a taste for the drug in adolescence faring worse on a test more usually used to spot the early signs of Alzheimer's in pensioners.

(File picture) Researchers from the Institute of Psychiatry at King's College London found teenagers who become hooked on cannabis risk long-term damage to their IQ

Importantly, the effects on IQ could still be seen in those who had not touched the drug for a year.

The results are significant because while cannabis has been blamed for relatively rare mental health problems such as schizophrenia, this is the first firm evidence of it wreaking damage on everyday life.

Professor Robin Murray, a consultant psychiatrist at the South London and Maudsley NHS Foundation Trust, said: 'It is, of course, part of folklore among young people that some heavy users of cannabis seem to gradually lose their abilities and end up achieving much less than one would have anticipated.

'This study provides one explanation as to why this might be the case.'
One of the researchers said: 'The simple message is that substance use is not healthy for kids.'

Official figures show that although drug use is falling among British schoolchildren, cannabis is still their drug of choice, with almost 8 per cent of 11 to 15 year olds questioned having used it in 2011.

 

The analysis, detailed in the journal Proceedings of the National Academy of Sciences, also found those who used the drug (pictured here) persistently from their teens did worse on a memory test

The eminent international research team, including some from the Institute of Psychiatry at King's College London, put more than 1,000 boys and girls through a battery of IQ tests when they were aged 13 and 14.

They did the same tests more than 20 years later, at the age of 38, and any differences were noted. They were also asked every few years if they had taken cannabis and, if so, how often.

 

'As with all recreational drugs, it is important that all young people are informed about the potential harms of cannabis use, through good quality drug education and well-resourced public health campaigns.'

Martin Barnes, DrugScope

 Unlike some previous studies, none had tried the drug when the research started, making it easier to tease out any effects of cannabis on the brain.

The results showed small falls in IQ in those who never or rarely used the drug and in those who had started to use it a lot as adults.

But in those who became hooked on cannabis in their teens, IQ fell by an average of eight points – the equivalent of going from being of average intelligence to being in the bottom third of the population.

Researcher Professor Terrie Moffitt, of the Institute of Psychiatry, said: 'Research has shown that IQ is a strong determinant of a person's access to college education, their lifelong total income, their access to a good job, their performance on the job, their tendency to develop heart disease and even early death.

'Individuals who lose eight points in their teens and twenties may be disadvantaged, relative to their same-age peers, in the most important aspects of life and for years to come.'

The analysis, detailed in the journal Proceedings of the National Academy of Sciences, also found those who used the drug persistently from their teens did worse on a memory test used normally to spot tell-tale signs of dementia.

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SCIENTISTS FIND SWITCH IN BRAIN THAT COULD CAUSE PSYCHOSIS

 

Earlier this month scientists revealed they have found a switch in the brain which may explain why smoking cannabis causes psychosis and addiction in more than one-in-ten users.

The team, at Aberdeen University found a genetic difference in the switch, probably inherited from early humans who smoked the drug in prehistoric times.

The difference may also explain why some people could be more susceptible to conditions such as obesity.

The chemical 'switch' discovered by researchers could explain by one in ten cannabis smokers suffer from psychosis and addiction issues.

The chemical 'switch' discovered by researchers could explain by one in ten cannabis smokers suffer from psychosis and addiction issues.

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And their friends told of them forgetting to return calls, pay bills and do errands.
With those who started taking cannabis persistently as adults suffering few ill-effects, the researchers say the drug may be particularly toxic in the teenage years, when the brain undergoes a rapid growth spurt.

Laurence Steinberg, a U.S. expert on the development of the adolescent brain, said: 'This study points to adolescence as a time of heightened vulnerability.

'The findings are pretty clear that it is not simply chronic use that causes the deficits but chronic use with adolescent onset.'

Professor Murray, whose own work has shown a clear link between cannabis use in teenage years and mental illness in later life, described the research as very impressive.

He said that if other studies come to the same conclusion 'it will be very important and public education campaigns should be initiated to let people know the risks'.

Martin Barnes, chief executive of charity DrugScope, said: 'Although the number of cannabis users in the UK has been falling consistently for some years, the risks to the health and wellbeing of those who do use it have not decreased.

'As with all recreational drugs, it is important that all young people are informed about the potential harms of cannabis use, through good quality drug education and well-resourced public health campaigns.'

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Study shows how cannabis impairs memory

By Kathleen Blanchard RN on March 4, 2012 - 10:59am for eMaxHealth


Researchers have uncovered how cannabis compounds impair memory. The reason is because cannabis interferes with neuronal connections in the hippocampus - an area of the brain responsible for spatial navigation and consolidation of information.

The study authors say the finding is important for optimizing medicinal use of marijuana. In the study they found THC in cannabis promotes activation of receptors that can induce long-term depression of the strength of glutamate receptors in the brain, which impairs spatial working memory.

The researcher team used mice to track receptors in the brain, finding the effect of cannabinoids in marijuana compounds. The current study specifically focused on CB1 brain receptors that are found primarily in the brain and nervous system.

The study, conducted by Giovanni Marsicano and colleagues at the Magendie Neurocentre (Inserm Research Unit 862, University of Bordeaux 2 found cannabinoids interrupt neural connections in the hippocampus region of the brain. When the compounds connect with brain receptors, signals are weakened, making it harder to perform simple tasks.

In tests performed in Petri dishes and in mice, the scientists found specific cells called astrocytes mediate CB1 receptors in the brain, which was not previously understood. THC was found to remove receptors for a compound called AMPA from the membranes of neurons that send signals throughout the brain.

The result is decline in working memory, manifested by short-term difficulty performing common tasks like calculating, reading, writing and thinking clearly.

"The description of cannabinoid-specific action mechanisms in the hippocampus should enable optimization of the therapeutic potential of cannabinoids, which is currently limited by significant adverse effects associated with their consumption".

The study was prompted by observations in animals and humans that cannabis impairs memory. Researchers for the current finding wanted to understand what happens in the brain. The finding, say the authors, could have implications for decisions about how marijuana is used medicinally.

“It’s always difficult to extrapolate from rodents to humans,” says Marsicano, “but marijuana impairs working memory in both species, so I expect that similar mechanisms are involved.” The goal would be to find compounds derived from THC, the active ingredient in cannabis that can treat pain and other diseases without affecting memory, by targeting neurons instead of astrocytes.

Source:
“Astroglial CB1 Receptors Mediate Cannabinoid Alterations of Synaptic Plasticity and Working Memory” Jing Ha, et al.
Cell, 2 March 2012

Image credit: Wikimedia commons

http://www.emaxhealth.com/1020/study-shows-how-cannabis-impairs-memory

Cannabis used to relieve pain

Cannabis is used for first time in hospitals to relieve pain of terminal cancer patients

Patients are being treated with medication derived from marijuana plants in hospitals for the first time as part of a trial.
Patients at North Manchester General and Fairfield in Bury were prescribed the drug, Sativex, which experts say can relieve pain by numbing muscles

The medication which is sprayed under the tongue up to 10 times a day does not give users a 'high'.

World first: Research nurse Sam Jole said studies into the new drug are groundbreaking. It is being tested on patients at North Manchester General Hospital and Fairfield Hospital in Bury

People who are terminally ill with cancer will initially take part in the trial but if successful, its use could be extended across the country and be used as a painkiller for other conditions.

Eight people have already been signed up, and 32 others will be recruited over the next two years.
The drug has been available on prescription in Britain as a treatment for multiple sclerosis since last summer - but it has not been used in hospitals before.

Sam Jole, senior research nurse at Pennine, the trust which runs North Manchester and Fairfield, has been involved in setting up the trials and identifying, recruiting and monitoring patients.

On trial: Sativex is derived from marijuana, numbing the muscles to relieve pain without a 'high'

He said: 'The majority of cancer research is focused on curing disease.
'Palliative care is an under-researched medical specialty and the studies are genuinely ground-breaking.

'I've been a research nurse for years and have never come across anything like it.
'It is very important to point out that patients using the spray do not experience the euphoria associated with the illegal recreational use of cannabis.

'It has passed strict tests for quality, safety and efficacy and doctors are already prescribing it for multiple sclerosis patients.'

Patients involved in the study will visit either North Manchester or Fairfield General for check-ups four times over a five-week period.
They will also be required to to report their pain scores and usage of painkillers every evening over the phone.
Around half of them will be prescribed the active drug and the rest will receive a placebo.
The drug, created by GW Pharmaceuticals, is made from two substances found in the marijuana plant, THC and CBD.

North Manchester General Hospital: One of the hospitals testing the cannabis-derived drug in hospitals for the first time

THC produces a high, but CBD counteracts it, and because Sativex is an oral spray, the drug is absorbed more slowly than if it was smoked so scientists say it is impossible to 'get high' from the treatment.

Dr Iain Lawrie, consultant and honorary clinical senior lecturer in palliative medicine at North Manchester, said: 'This study is an exciting development in the field of cancer pain management.
'Initial clinical observations suggest that Sativex will have an important role to play in this complex area of palliative care.'

2nd September 2011
Dailymail.co.uk

www.dailymail.co.uk/health/article-2033021/Doctors-treat-patients-pain-relieving-cannabis-drug-used-time-hospitals.html