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December 29th, 2006, 01:47 AM
LONDON, Ontario, Nov. 27 -- Patients dependent on alcohol have electrical activity in their brains that is similar to patterns seen in those with major depression, according to researchers here.

Action Points

? Explain to interested patients that this study shows that differences in patterns of electrical activity in the brain appear to be associated with alcohol dependence.

? If the research is confirmed, it may provide a way to determine who is vulnerable to alcoholism before the problem occurs.

Measured by electroencephalograph, brains of patients diagnosed with alcohol dependence had lower activity in the left anterior cortex than in the right, found Elizabeth Hayden, Ph.D., of the University of Western Ontario.

Such a pattern has previously been seen in patients with major depression or a lifetime history of depression, Dr. Hayden and colleagues reported in the December issue of Alcoholism: Clinical & Experimental Research.

Surprisingly, however, those who were both dependent on alcohol and suffering from depression had less of an imbalance of electrical activity between the two brain regions, the researchers found.

"Left frontal activity may reflect brain systems involved in acquiring rewards and the positive moods we feel when we obtain a desirable object or goal," Dr. Hayden said. "Conversely, right frontal activity may be involved in inhibiting behavior in the face of negative consequences and the anxiety we feel in those circumstances."

An imbalance -- possibly partly genetically based -- has been associated with "individual differences in emotional traits that may be linked to psychopathology vulnerability" (including depression), Dr. Hayden and colleagues reported.

The findings come from a study a so-called α-band activity in 193 alcohol-dependent patients and 108 controls with no history of major affective illness, eating disorder, anxiety disorder, alcohol or drug dependence, or antisocial personality disorder.

Statistical analysis of the variations in activity in the α-band -- the standard approach in the field -- showed significant differences between controls and cases, Dr. Hayden and colleagues said. Specifically, alcohol-dependent patients were more likely (at P=0.003) to have lower activity levels in the left region than were controls.

That said, the researchers reported, more research is needed. "Although this finding dovetails with research that indicates shared genetic influences on these disorders, it is important to note that the difference we found between controls and alcoholic subjects was pretty small," Dr. Hayden said.

On the other hand, when the researchers looked within the alcohol-dependent group to see whether other disorders had a cumulative effect, they found a "puzzling" result -- an asymmetry that was actually less among subjects with comorbid depression.

One possible explanation, Dr. Hayden and colleagues said, is that they only looked at males, because there were too few females in the study with comorbid depression. At least one previous study found the asymmetry only in females with depression, they noted.

The results are "compelling and suggest that EEG asymmetry may be an index of a general vulnerability to psychopathology," said Emily Grekin, Ph.D., a psychologist at Wayne State University in Detroit who was not involved in the research.

She noted that it is well established that electrical asymmetry is linked to depression, but little is known about any possible link to alcohol-dependence, although the two conditions are often seen together. "Dr. Hayden's study is the first to directly address this issue," she said.

The finding may be useful in understanding who is vulnerable to alcoholism, Dr. Hayden said.

"We know from research with preschoolers and infants that individual differences in frontal asymmetry may be meaningfully linked to behavior and personality even early in life," she said, adding that these brain differences appear to exist before problems develop.

A next step might be to find out "whether the same is true of frontal brain activity in alcoholism, possibly by looking at the children of alcoholics," she said.