Study shows promise of Parkinson’s therapy for alcohol use disorder

A form of therapy currently used to treat Parkinson’s disease may be able to help dramatically reduce alcohol use among chronic heavy drinkers, research suggests.

The study in macaque monkeys found that implanting a specific type of molecule in the brain may prevent a return to excessive alcohol use after a period of abstinence.

The gene therapy procedure involves brain surgery, and researchers say this could be useful in the most severe cases of alcohol use disorder.

Co-principal investigator and co-corresponding author Krystof Bankiewicz, professor of neurological surgery at Ohio State College of Medicine in the US, said: “This gene-therapy approach targets changes in dopamine function in the brain’s mesolimbic reward pathway that are caused by chronic alcohol use.

“Our findings suggest that this treatment can prevent relapse without requiring long-term treatment adherence by patients.”

According to the experts, people with alcohol use disorder (AUD) commonly experience repeated cycles of abstinence followed by relapse.

Excessive alcohol use alters certain nerve tracts in the brain that involve the release of the neurotransmitter dopamine.

These neurons make up a specific pathway which plays a major role in alcohol and drug addiction.

The implanted virus is not harmful and carries a gene that codes for the protein known as glial-derived neurotrophic factor, or GDNF.

In the study it was injected in a specific area of the brain of a group of rhesus macaque monkeys that voluntarily and heavily drink ethanol diluted in water.

After four macaques underwent the procedure, researchers found their consumption dropped by more than 90% compared with those who did not.

Co-senior author Kathleen Grant, professor and chief of the division of neuroscience at Oregon Health and Science University’s Oregon National Primate Research Centre, said: “Drinking went down to almost zero.

“For months on end, these animals would choose to drink water and just avoid drinking alcohol altogether.

“They decreased their drinking to the point that it was so low we didn’t record a blood-alcohol level.”

In the case of AUD – a problematic pattern of alcohol use leading to significant impairment or distress – chronic drinking decreases the release of dopamine – a feelgood chemical released in the brain.

Prof Grant said: “Dopamine is involved in reinforcement of behaviour, and in people finding certain things pleasurable.

“Acute alcohol use can increase dopamine. However, by drinking it chronically, the brain adapts in such a way that it decreases the release of dopamine.

“So when people are addicted to alcohol, they don’t really feel more pleasure in drinking.

“It seems that they’re drinking more because they feel a need to maintain an intoxicated state.”

The procedure used in the study is already used in adult patients with Parkinson’s disease and in children to treat a rare genetic disorder known as aromatic L-amino acid decarboxylase deficiency that, among other symptoms, causes difficulty with movement.

Because the new study, published in Nature Medicine, describes a form of treatment that permanently alters the brain through surgery, it would be limited to those with the most severe forms of alcohol use disorder.