Both separately and in concert, smoking and drinking cause harm to the brain -- bad news for the majority of alcoholics who also smoke.

A recent symposium sponsored by the Research Society on Alcoholism addressed the impact of smoking and alcoholism on brain neurobiology and function. "Recent neuroimaging studies of chronic smokers have shown brain structural and blood-flow abnormalities," said Dieter J. Meyerhoff, professor of radiology at the University of California at San Francisco and an associate researcher at the Veterans' Affairs Medical Center in San Francisco. "Specific cognitive dysfunction among active chronic smokers has been reported for auditory-verbal learning and memory, prospective memory, working memory, executive functions, visual search speeds, psychomotor speed and cognitive flexibility, general intellectual abilities, and balance. We also believe that the adverse effects of smoking, just like drinking, likely take many years to impact brain function significantly, and interact with age to produce a level of dysfunction that is apparent on cognitive tests."

"These effects are similar to effects that in the past have been attributed solely to the excessive consumption of alcohol," he added. "As chronic alcohol drinking and chronic smoking more often than not co-occur, researchers have begun to realize that the brain effects previously attributed to alcohol drinking alone may in fact be the result of both drinking and smoking. This realization may have consequences for how we look at treatment for alcohol-use disorders."

Participants at the June 2005 symposium said that genetics as well as the pharmacological interplay between alcohol and nicotine may play a role in the fact that so many heavy drinkers are also heavy smokers.

"Any behavioral manifestation, including alcoholism or addiction to nicotine, is a result of genetic-environment interactions," said researcher Yousef Tizabi. "Drugs, including alcohol and nicotine, may affect different individuals differently, depending on their genetic make-up. Similarly, drug-drug interactions are also influenced by genetic factors. Therefore, co-morbidity of drinking and smoking can be considered to be a final outcome of genetics, environment, and pharmacological interactions between alcohol and nicotine."

Researchers said that smoking may affect a key amino acid (GABA) in the brain, meaning that drug therapy for alcohol withdrawal may have different effects on smokers than nonsmokers. Scientists also reported that MRI studies have shown that smoking makes alcohol-induced brain-tissue loss and neuronal injury worse among alcoholics who have recently detoxed. "Our analyses showed that chronically smoking alcoholics have greater brain abnormalities -- that is, less brain tissue measured by structural MRI, and more neuronal injury measured by MRSI -- at the beginning of their treatment for alcoholism than nonsmoking alcoholics." said Meyerhoff. "And both groups had more brain abnormalities than nonsmoking light drinkers."

The symposium results were published in the February 2006 issue of the journal Alcoholism: Clinical & Experimental Research.