A depressed man drinks whiskey.
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Alcoholics have weakened communication between the frontal lobe of the brain and a brain region that plays a key role in motor control, a new study finds.
Communication between the frontal lobes, which are responsible for judgment and decision-making, and the motor region called the cerebellum remained hobbled even a week after alcoholics stopped drinking, though researchers aren't yet sure what this finding may mean.
The researchers speculate the hobbled relationship between these regions could be the result of injury to one or both of these parts of the brain, a disruption to the path that connects them, or even compensation due to injuries elsewhere in the brain.
"It could even be that a weakened relationship between these brain regions was present prior to when a person started drinking, which actually predisposes people to alcoholism in the first place," study researcher Baxter P. Rogers, a professor at the Vanderbilt University Institute of Imaging Science, said in a statement.
Previous research has shown that chronic drinking can cause changes in the structure, metabolism and function of the brain. The cerebellum is one of the brain regions most sensitive to alcohol, according to the National Institute on Alcohol Abuse and Alcoholism, and damage can cause problems with movement, balance and coordination. [10 Intoxicating Alcohol Facts]
To understand this damage, Rogers and his colleagues asked 10 patients with chronic alcoholism to have their brains scanned in a functional magnetic resonance imaging (fMRI) machine. This scanner measures blood flow to different regions of the brain, measuring which are active during any given task.
In this case, the alcoholic patients, all of whom had been alcohol-free for five to seven days and had passed the withdrawal phase, were simply told to tap their fingers. As simple as this motion seems, it requires activity in both the cerebellum and the frontal cortex, areas the researchers wanted to investigate.
The alcoholic patients were capable of producing the same number of finger taps per minute as nonalcoholics tested. But their brains used different methods to produce this movement, the researchers found. There were fewer functional connections between the frontal lobe and the cerebellum in alcoholic brains, which means that the neurons in the two regions were not communicating very strongly.
The finding suggests that the alcoholics are compensating for an injured brain, Rogers said.
"They may need to expend more effort, or at least a different brain response, to produce a normal outcome," he said.
If the task were more complex than finger-tapping, Rogers said, it's likely that the alcoholic brains would be unable to compensate, and the movement would be impaired.
The research, published today (Nov. 15) in the journal Alcoholism: Clinical & Experimental Research, isn't the first to find problems in the cerebellum-frontal lobe circuit. But it is the first to find that the problems go even deeper than previously suspected, affecting even simple tasks that alcoholics are still able to carry out.
"Our study allows us to infer that changes in brain strategies are employed in performance of the task, which may lead to new approaches in rehabilitation," Rogers said.