A research team led by scientists from the Ernest Gallo Clinic and Research Center at the University of California, San Francisco has identified circuitry in the brain that drives compulsive drinking in rats, and likely plays a similar role in humans.
The scientists found they could reduce compulsive drinking in rats by inhibiting key neural pathways that run between the prefrontal cortex, which is involved with higher functions such as critical thinking and risk assessment, and the nucleus accumbens, a critical area for reward and motivation.
The authors noted that there are already several FDA-approved medications that target activity in these pathways, thus potentially opening an accelerated track to new treatments for compulsive drinking.
The study describing their finding was published online on June 30 in Nature Neuroscience.
The study was conducted on rats that regularly drank 20 percent alcohol. The rats drank both unmixed alcohol and alcohol mixed with extremely bitter quinine, said senior investigator F. Woodward Hopf, PhD, an assistant adjunct professor of neurology at UCSF.
Hopf explained that this alcohol-quinine solution, which he described as "like a vodka tonic without the sugar," is often used as a rodent model of compulsive drinking, or "drinking in the face of negative consequences." In rats, he said, the negative consequence is the bitter taste, while in humans who drink compulsively, "the negative consequences are profound: people continue to drink despite the potential loss of jobs, marriages, freedom, even their lives."
In the United States, alcoholism is estimated to cost $224 billion per year - almost $2 per drink - mostly from lost productivity and crime, and leads to 100,000 preventable deaths per year.
The drinking rats showed a notable increase in the NMDA receptor (NMDAR), which lead author Taban Seif, PhD, a Gallo Center researcher, called "a molecule that excites the brain." When the rats were injected with an NMDAR blocker, their consumption of quinine-laced alcohol dropped significantly, while regular alcohol use was unaffected. "In other words, only the compulsive drinking was affected," said Seif.