New brain pathways linked to addiction have been identified by researchers at University of New South Wales. They showed that by manipulating the pathways, drug seeking behavior and motivation for alcohol can be reduced.

Although the discovery was made in lab rats, it opens up a new target for developing treatments for drug and alcohol addiction in humans, which could include deep brain stimulation.

First author of the study, Dr Asheeta Prasad from UNSW’s School of Psychology, said:

“Current drug therapies are generally poor because we still don’t completely understand how the brain’s neural circuits contribute to different forms of relapse. Mapping these circuits is crucial if we are to move forward in treating drug and alcohol addiction."

Ventral Pallidum Pathways

The researchers studied the brain’s ventral pallidum (VP), which is responsible for regulating motivation, behaviour, and emotions.

Previous studies have shown that activity in ventral pallidum pathways has been implicated in a variety of drugs of abuse including cocaine, amphetamines and alcohol. Importantly, the ventral pallidum is a key brain region for promoting relapse, with VP neurons activated during different forms of relapse.

The UNSW researchers identified for the first time that two distinct VP output brain pathways are necessary for different forms of alcohol-related relapse. They found that the brain pathways from the VP to the subthalamic nucleus, a small lens-shaped nucleus in the brain, and the ventral tegmental area, part of the mid-brain, are switched on during relapse behavior.

The study has found a novel node in the brain circuitry for relapse. Drug addiction is a chronic relapsing disorder characterised by cycles of drug abuse, abstinence and relapse.

When the researchers switched off these brain pathways, drug seeking behavior and motivation for alcohol was reduced in rats. The finding opens up the potential for using deep brain stimulation in the treatment of addiction.

“Deep brain stimulation of the subthalamic nucleus is currently used to manage Parkinson’s disease, but has not yet been tested in the treatment of addiction,” Dr Prasad said. “It is a certainly a potential future treatment for relapsing disorders such as drug addiction and obesity."

A. A. Prasad et al. Ventral Pallidum Output Pathways in Context-Induced Reinstatement of Alcohol Seeking Journal of Neuroscience (2016). DOI: 10.1523/JNEUROSCI.2580-16.2016

Image: Shutterstock/University of New South Wales

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