Scientists at Aberdeen University have made progress in using medical cannabis to treat illnesses.
Researchers have identified a part of a gene which could affect how people respond to cannabis-based treatment for diseases, addiction and obesity.
However, the treatment could be hampered by the the unpredictability of adverse side-effects which can include depression and psychosis.
Currently, there is no way to predict which people will experience these side-effects, but Dr Alasdair MacKenzie and his team are working on that.
Dr MacKenzie and Dr Elizabeth Hay from the School of Medicine, Medical Science and Nutrition used an innovative method to study specific areas of genetics which affect cannabis receptors in the brain.
According to their research, these previously ignored gene regions may be the key to understanding why people respond differently to some drugs.
Dr MacKenzie said: “We found that there was a genetic switch within the cannabis receptor in humans and mice and which had remained almost unchanged for hundreds of millions of years.
“This switch controlled the expression of the receptor in a part of the brain that modulates mood.
“We found that when we disrupted this switch in mice, alcohol intake and anxiety levels were reduced, as were the effects of cannabinoids.
“This means that we are helping to establish a functional role for this switch which may help us understand how it responds to cannabinoids.
“This will contribute to unlocking the potential of medicinal cannabis.”