Although alcoholism is a common disease that affects millions of people worldwide, the underlying causes have not been fully understood – until now. Scientists say they've discovered the brain cells responsible for inciting alcohol cravings.
A study published in the journal Neuroscience by researchers at the Texas A&M Health Science Center College of Medicine has found that the consumption of alcohol alters the function and structure of neurons in the dorsomedial striatum. This part of the brain is known to be important in goal-driven behaviors.
The researchers' key finding lies in what are known as medium spiny neurons – the main type of cell in the striatum. Using an animal model, the scientists determined that alcohol changes the physical structure of those neurons.
Each medium spiny neuron contains one of two types of dopamine receptors: D1 or D2. Therefore, they are classed as either D1 or D2 neurons.
The D1 neurons become much more excitable following the consumption of large amounts of alcohol.
"If these neurons are excited, you will want to drink alcohol. You'll have a craving," Dr. Jun Wang, lead author and an assistant professor in neuroscience and experimental therapeutics, said in a press release.
This creates a cycle – drinking causes easier activation of the D1 neurons, which leads to more drinking.
As the neurons become more sensitive, they require less stimulation to become activated – meaning that just one sip of wine can trigger a craving for an entire bottle.
The alcohol-consuming animal models showed an increased preference to drink large quantities of alcohol. However, when they were given a drug to at least partially block the D1 receptor, they showed a much lessened desire to drink alcohol.
Meanwhile, a drug that inhibited the D2 dopamine receptors had no effect – thereby supporting the finding that D1 neurons are the ones responsible for alcohol cravings.
“If we suppress this [D1] activity, we’re able to suppress alcohol consumption,” Wang said. “This is the major finding. Perhaps in the future, researchers can use these findings to develop a specific treatment targeting these neurons.”
Indeed, Wang and his team hope the finding can one day help those battling addictions.
“My ultimate goal is to understand how the addicted brain works,” Wang said. “And once we do, one day, we’ll be able to suppress the craving for another round of drinks and ultimately, stop the cycle of alcoholism."
The study was co-authored with researchers from the University of California San Francisco, and supported by a grant from the National Institute on Alcohol Abuse and Alcoholism (NIAAA).