Unwinding after work with some wine or heading out for drinks with friends is a common practice for relieving stress. It works because alcohol changes neurotransmitter levels in the brain.

But chronic drinking has been linked by a series of studies to high levels of the stress hormone cortisol , which can be dangerous to health. And the withdrawal that comes when alcoholics abstain from drinking has been linked to the same danger.

High concentrations of cortisol are associated with neurotoxicity, a condition that impairs memory, decision-making, attention span and learning, according to researchers from a number of institutions, including King's College London, the University of Kentucky and the University of London, who participated in the study review. Cortisol is released by the adrenal glands and by the brain during moments of high stress. It is also released during alcohol consumption.

"It's the chronic drinking that causes the neurotoxicity," researcher H.J. Little, a professor at the National Addiction Centre at King's College London, told MyHealthNewsDaily, "so chronic high levels of alcohol consumption are not good for the brain."

Neither is going from chronic drinking to abstinence, according to researcher Dr. Abi Rose, a lecturer at the University of Liverpool.

Because abstinence is a huge shock to the system, it can lead to degeneration of the brain's neurons, Rose said.

"Alcoholics who display the most-severe cognitive impairments during withdrawal are those who also have the highest cortisol levels," Rose said. "Therefore, cortisol function seems to play a significant role in continued alcohol dependence and risk of relapse."

The cortisol connection

The findings give scientists a better understanding of how stress hormones are connected to the cognitive problems experienced by alcoholics who give up drinking, according to the review. The findings also could provide better insight into why alcoholics are prone to relapse, Rose said. However, she said, more research is needed to see whether cortisol dysfunction is a risk factor for alcohol dependence.

"In an ideal world, it would always be preferable not to become a chronic drinker in the first place," Rose said. "Once alcohol dependence has developed, the benefits from stopping drinking outweigh the potential negative consequences of withdrawal." But because serious problems can occur during withdrawal, it's essential that the individual receives appropriate care, she said.

The studies included in the review were conducted in both humans and rats. In one study conducted by Little, rats' stress hormone levels remained high for two months after they stopped consuming alcohol. That period is equivalent to five human years, Little said.

Link to health problems

In general, stress responsiveness is blunted in alcoholics because their base levels of cortisol are raised to begin with, said Dr. Lindsey Grandison, a neuroscience and behavior researcher at the National Institute on Alcohol Abuse and Alcoholism. Grandison was not associated with the research, but the institute, in Bethesda, Md., helped fund the studies in the review.

"So the outcome is you get a different level of exposure to the [stress hormones] during stress," Grandison said. "And along with the other changes that occur with alcoholism, it may contribute to relapse or other problems."