The substances most frequently used by alcohol-dependent individuals are tobacco products; roughly 80 percent of alcohol-dependent individuals report smoking regularly.
Although brain morphology, neurometabolism, and neurocognition are known to be adversely affected by chronic, heavy alcohol consumption, little research has examined the independent effects of cigarette smoking or its potentially compounding effects on alcohol-induced brain damage.
"While the effects of cigarette smoking on the heart, lungs, central and peripheral vascular systems, and its carcinogenic properties have been studied for many years in humans, very little is known about its effects on the brain and its functions," said Timothy C. Durazzo, a neuropsychologist and neuroscience researcher at the San Francisco Veterans Administration Medical Center and corresponding author for the study.
What is known, said Durazzo, is that smokers tend to consume more alcohol than non-smokers.
Researchers compared 24, one-week-abstinent alcoholics (14 smokers, 10 nonsmokers) in treatment with 26 light-drinking "controls" (7 smokers, 19 nonsmokers) on magnetic resonance spectroscopic imaging measures of common brain metabolites in gray and white matter of the major lobes, basal ganglia, midbrain and cerebellar vermis.
"Results indicate that chronic cigarette smoking increases the severity of brain damage associated with alcohol dependence," said Durazzo.
Our studies show that this exacerbation of the alcohol-induced brain damage is most prominent in the frontal lobes of individuals studied early in treatment."
Durazzo noted that frontal-lobe functions are applied in multiple contexts of everyday life.
"Therefore, exacerbation of alcohol-induced damage to the tissue of the frontal lobes by chronic cigarette smoking may further compromise recovering alcoholics' ability to successfully execute more challenging activities of daily living or accurately judging or anticipating the consequences of their actions, particularly with increasing age," he said.
Cigarette smoking, independent of alcohol consumption, was also found to have adverse effects on neuronal viability and cell membranes in the midbrain and on cell membranes of the cerebellar vermis.