Imaging unveils brain damage from chronic drinking and smoking

Neuroimaging techniques are revealing the impact of chronic smoking on alcohol dependence, with implications for treatment.

Nationwide, an estimated 80% of alcoholics are also chronic smokers. Yet research considering the relationship between addiction to both tobacco and alcohol is scant.

To help fill the knowledge gap, a series of studies about alcohol dependence and chronic smoking was presented last June at a Research Society on Alcoholism symposium in Santa Barbara, CA. Summaries of the symposium presentations appeared in the February issue of Alcoholism: Clinical and Experimental Research.

Researchers from Yale University's psychiatry department used SPECT imaging to measure the density of GABA-A receptors in the brain and proton MR spectroscopy to measure the concentration of the inhibitory amino acid GABA. They found that smoking and nonsmoking alcoholics have different concentrations of GABA and its receptors during alcohol withdrawal stages.

The research suggests that alcoholics smoke to counteract the negative consequences of GABA receptor changes related to chronic drinking. Smoking and nonsmoking alcoholics may react differently to benzodiazepines, a common drug used for alcohol withdrawal treatment.

Another study examined the relationship between chronic drinking and smoking in a group of 60 veterans admitted for alcoholism treatment to the San Francisco VA Medical Center/University of California, San Francisco. About 40% of these veterans were nonsmokers, much higher than the national rate for alcoholics.

In comparison with previous investigations in the field, researchers analyzed smaller regions of the brain and used a wider range of MR methods, including structural, metabolic, and perfusion- and diffusion-weighted imaging.

The study found that chronic smoking and chronic drinking both have similar detrimental effects on certain brain structures and metabolites. Alcoholics who smoke chronically have greater brain injuries than nonsmoking alcoholics. After quitting drinking, smokers appear to recover more slowly from brain injuries associated with alcoholism than do nonsmokers, perhaps because chronic smoking continues to damage the brain.

"During abstinence from alcohol, smoking alcoholics recover at different rates and in different ways than nonsmoking alcoholics. This suggests the two groups may also react differently to treatment," said Dr. Dieter Meyerhoff, a professor of radiology at UCSF. "If you want to help alcoholics recover from alcohol, it may make sense to address their chronic smoking problems at the same time."

In another study set to be published in May, the same research group looked at brain perfusion in nonsmoking versus smoking alcoholics.

Conventional wisdom has held that alcoholism is associated with brain perfusion deficits. But researchers found that some of the perfusion deficits in their study were due to chronic smoking, rather than chronic drinking.

"More and more, we realize brain damage detected in alcoholism is partly due to chronic cigarette smoking," Meyerhoff said.

The more researchers know about the nature of an alcoholic's brain injury, the easier it will be to treat patients effectively, he said.

"You need to know what the injury is and how it is acquired in order to design effective drug treatments," he said.

For more information from the Diagnostic Imaging archives:

CT exposes women's vulnerability to alcoholism

Imaging shows effects of alcohol use on brain

Imaging untangles mystery of drug-addicted brain

Pot smokers, schizophrenics show similar brain responses