‘Cannabis addiction’ gene has been discovered by scientists

‘Cannabis addiction gene’ that could make people more likely to abuse the drug is discovered by scientists in a ‘really important’ breakthrough

• Gene CHRNA2 regulates a ‘nicotine receptor’ in the brain, scientists have said 
• Low levels of this receptor has been linked to an increased of marijuana abuse
• Discovery could help medics treat and even prevent marijuana addiction 

A gene thought to raise your risk of becoming addicted to cannabis has been discovered by scientists.

Danish researchers examined the genomes of thousands of people to uncover the potential genetic cause of cannabis-use disorders. 

Results revealed people with cannabis-use disorders were more likely to have variants in their CHRNA2 gene.

Experts hailed the ‘really important’ finding, saying it may pave the way to identify people who may be at risk of abusing the drug.

CHRNA2 regulates a ‘nicotine receptor’ in the brain. Low levels of this receptor has been linked to an increased risk of cannabis abuse.

Scientists have discovered a gene that may raise a person’s risk of cannabis addiction (stock)

This could help medics treat and even prevent addiction to cannabis, the team at Aarhus University added. 

Members of the public cannot currently find out through tests if their CHRNA2 gene has ‘abnormalities’.

Cannabis-use disorder (CUD), or addiction, has a ‘strong genetic component’, the researchers wrote in the journal Nature Neuroscience.

To uncover if an exact section of DNA is responsible, the researchers analysed the genes of 2,387 people with CUD from throughout Denmark.

The users’ genomes were compared against those of 48,985 non-users. The study was then repeated among an additional 5,501 users and 301,041 ‘controls’.

CHRNA2 regulates nicotinic acetylcholine receptors, which respond to both drugs and the chemical messengers that are sent between nerve cells.

The researchers then compared their findings with studies that looked at how DNA impacts thinking skills.

This revealed people with a higher number of variants for the DNA that regulates cognition are also more likely to use cannabis.   

‘We need to undertake even more research into how the genetic differences in the genome contribute to the development of cannabis abuse,’ 

Study author Dr Ditte Demontis said further research is needed to confirm the link his team uncovered.

He added: ‘And we need to map out the precise biological mechanisms that lead to one person having a higher risk of becoming a substance abuser than another.

‘Our hope is to be able to improve treatment and perhaps in the long-term even prevent this abuse.’ 

Ian Hamilton, senior lecturer in addiction and mental Health at the University of York, who was not involved in the study, welcomed the findings.

He told MailOnline: ‘This is a really important development. The researchers have been able to isolate a gene associated with cannabis dependence. 

‘This doesn’t necessarily mean everyone with this gene will go on to become dependent on cannabis.

‘But it does suggest that they are at increased risk of becoming dependent if they use cannabis.’

He added: ‘Up to now we have struggled to know who is at risk of becoming dependent and had to wait until people present to specialist treatment before knowing they had a problem. 

‘This new research opens up the potential to identify which individuals are at risk and start a conversation about how they can avoid problems developing with cannabis.’

Cannabis is the most commonly taken drug among young people in the UK, according to statistics from the Home Office Crime Survey for England and Wales.

Some 975,000 of 16-to-24 year olds (15.8 per cent) used the substance in 2014/15.

Of the 14million people of all ages in the UK who have used marijuana, 11 per cent have developed a dependency, UK Addiction Treatment Centres data shows.

It is also the most commonly-used drug in the US, with around 22.2million people using it a month, according to the 2015 National Survey on Drug Use and Health. 

WHAT EVIDENCE IS THERE CANNABIS INCREASES RISK OF MENTAL HEALTH ILLNESS? 

Schizophrenia: Researchers questioned more than 6,500 teenagers aged 15 and 16 on their cannabis use. They were monitored until the age of 30. Smoking cannabis just five times as a teenager can triple the risk of psychotic symptoms alongside major depression and schizophrenia in later life, according to the study at The Academy of Finland, published in the British Journal of Psychiatry in March 2018.  

Socially unacceptable behaviour: Researchers from the University of Montreal analysed around 4,000 13-year-olds from 31 high schools in the surrounding area for four years. Going from being an occasional marijuana user to indulging every day increases the risk of psychosis by up to 159 percent. Frequently abusing the substance also significantly reduces a user’s ability to resist socially unacceptable behavior when provoked. The research was published in the Journal of Child Psychology and Psychiatry in July 2017.

Negative emotions: Scientists at the National Institute on Alcoholism and Alcohol Abuse in Bethesda analysed 60 people, half of which were cannabis dependent. The study’s participants completed a questionnaire that asked them about their feelings of stress, aggression, reactivity and alienation. Cannabis users are more likely to experience negative emotions, particularly feeling alienated from others. People who use marijuana are significantly more likely to feel that others wish them harm or are deceiving them. The research was published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging in January 2018.

Panic attack reaction: Researchers from the University of Vermont scanned the brains of teenagers in Europe and found just one or two joints is enough to change the structure of a teenager’s brain. It could cause changes affecting how likely they are to suffer from anxiety or panic. Researchers found 14-year-old girls and boys exposed to THC had a greater volume of grey matter in their brains. This means the tissue in certain areas is thicker – the opposite of what usually happens during puberty, when teenagers’ brain matter gets thinner and more refined. The study was published in The Journal of Neuroscience in January 2019.

Bipolar: Researchers at Warwick Medical School analysed 3,370 women’s cannabis use at 17 years old. At 22-to-23 years old, the participants completed a questionnaire. People who used cannabis at least two-to-three times a week at 17 years old are more likely to experience hypomania in their earlier 20s. Hypomania is defined as elevated mood alongside irritability or an inflated ego, an unrealistic sense of superiority, a reduced need for sleep and frenzied speech. Such symptoms frequently occur in bipolar disorder sufferers. The research was published in Schizophrenia Bulletin in December 2017.

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