A key ingredient in marijuana curbs epilepsy seizures by more than 50 percent, new research suggests.

Taking the marijuana-derived supplement cannabidiol (CBD), alongside commonly-prescribed medications, can more than halve the frequency of epilepsy patients' seizures, a study review found today.

The dual treatment also causes nearly one in 10 patients to be seizure-free, while up to half report an improved quality of life after incorporating the supplement into their drug regimen, the research adds.

This comes after research released last month by Vanderbilt University supported similar outcomes.

CBD is a nutritional supplement that is thought to possess a range of medicinal benefits and has been reported to help people suffering from migraines, psoriasis, acne and depression.

It does not contain any THC, which is the psychoactive component of cannabis that makes users 'high'.

Nearly one in three epilepsy patients are resistant to existing treatments and continue to endure seizures.

Taking the marijuana-derived supplement cannabidiol, alongside commonly-prescribed medications, can reduce the frequency of epilepsy patients' seizures by at least 50 per cent

DOES CANNABIS INCREASE THE RISK OF PSYCHOSIS? Going from being an occasional marijuana user to indulging every day increases the risk of psychosis by up to 159 percent, research revealed in July 2017. Marijuana is thought to cause psychosis-like experiences by increasing a user's risk of depression, a study found. The two mental health conditions have previously been linked. Frequently abusing the substance also significantly reduces a user's ability to resist socially unacceptable behavior when provoked, the research adds. Study author Josiane Bourque from the University of Montreal, said: 'Our findings confirm that becoming a more regular marijuana user during adolescence is, indeed, associated with a risk of psychotic symptoms. '[Psychosis symptoms] may be infrequent and thus not problematic for the adolescent, when these experiences are reported continuously, year after year, then there's an increased risk of a first psychotic episode or another psychiatric condition.' The researchers, from the University of Montreal, analyzed around 4,000 13-year-olds from 31 high schools in the surrounding area. Every year for four years, the study's participants completed questionnaires about any substance abuse and psychotic experiences. Psychotic symptoms included perceptual aberration - for example feeling that something external is part of their body - and thinking they have been unjustly badly treated. The participants also completed cognitive tasks that allowed the researchers to assess their IQ, memory and stimuli response. Advertisement

Further research is required

The researchers, from the University of New South Wales, stress their findings are only in young patients, adding investigations should be carried out in people of varying ages with different forms of epilepsy.

The review was conducted by analysing six studies with a total of 3,420 epilepsy patients.

The participants, who had an average age of 16, had rare forms of the condition that had not responded to standard treatments, such as valproate and carbamazepine.

CBD's effectiveness as an add-on to standard epilepsy treatment was investigated.

The findings were published in the Journal of Neurology Neurosurgery & Psychiatry.

Alcohol damages the brain more than cannabis

This comes after research released last month suggested alcohol damages the brain more than cannabis.

Unlike booze, marijuana does not affect the size or integrity of white or grey matter in the brain, even after years of exposure, a study found.

Grey matter enables the brain to function, while white controls communication between nerve clusters.

Study author Professor Kent Hutchison from the University of Colorado Boulder, said: 'While marijuana may also have some negative consequences, it definitely is nowhere near the negative consequences of alcohol.'

The scientists add, however, research into cannabis' mental effects are still very limited.

Lead author Rachel Thayer said: 'Particularly with marijuana use, there is still so much that we don't know about how it impacts the brain.'

In the US, 44 percent of those aged 12 or over have used cannabis at some point in their lives.

Washington, Oregon, California, Alaska and Colorado have legalised marijuana for medical or recreational use.