It comes naturally to stop doing something if it consistently leads to adverse consequences. For example, most individuals with lactose-intolerance steer away from milkshakes. However, alcoholics continue their behavior, no matter what type of trouble or danger their drinking habits eventually lead to. A new study suggests this is not a character flaw but rather the result of a specific enzyme whose production is shut off at the onset of alcohol dependency.

The enzyme, PRDM2, is related to impulse control and a study conducted by researchers at Linköping University in Sweden has found that the enzyme is turned off in nerve cells in the frontal lobe when alcohol dependence develops. This finding suggests that impulse control is impaired for individuals with alcohol dependency, and may explain why alcoholics consistently make poor decisions when it comes to their drinking behavior.

PRDM2 controls the expression of several genes that are necessary for effective signalling between nerve cells. When too little enzyme is produced, no effective signals are sent from the cells that are supposed to stop the impulse," Markus Heilig, professor of psychiatry and head of the Center for Social and Affective Neuroscience (CSAN) at Linköping University, explained in a recent statement .

For the research, the team explored the role of PRDMA in alcohol dependent rats and observed that lower levels of the enzyme in the rodent’s system disrupted their impulse control. As a result, the lab rats continued to drink alcohol even when the experience was unpleasant and quickly relapsed into their dependency when stressed out. To ensure that it was infact PRDM2 deficiency that was causing this change in these animals’ behavior, the team purposely knocked out the gene in the rats who were not dependent on alcohol. These rats also had no impulse control.

The findings could have wide reaching implications, not only for alcoholism but for all types of addictive illnesses.

“Now that we're beginning to understand what's happening, we hope we'll also be able to intervene. Over the long term, we want to contribute to developing effective medicines, but over the short term the important thing, perhaps, is to do away with the stigmatisation of alcoholism," Heilig concluded.

Source: Heilig M, Barbier E, Johnstone A, Khomtchouk B, et al. Dependence-induced increase of alcohol self-administration and compulsive drinking mediated by the histone methyltransferase PRDM2. Molecular Psychiatry. 2016

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