December 1, 2011 — Alcohol abuse appears to be much more detrimental to the female brain than to the male brain, new research suggests.
Investigators from the multidisciplinary Gothenburg Alcohol Research Project in Sweden found that after 4 years of excessive drinking, women experienced the same loss of serotonergic function that occurred in men who had been abusing alcohol for 12 years.
"We have to be aware that women are more vulnerable to excessive drinking, not just bodily harm but also [harm] to the brain. We also have to be aware that prevalent psychiatric disorders such as depression and anxiety, which are related to imbalance in the serotonin system and which women often are seeking help for, may also be influenced by excessive drinking," principal investigator Claudia Fahlke, PhD, from the Department of Psychology, University of Gothenburg, Göteborg, Sweden, told Medscape Medical News.
The study was published online July 28 in Alcoholism: Clinical & Experimental Research and will appear in the January 2012 print edition of the journal.
First Study of Its Kind
According to the study, alcohol dependence has been associated with reduced function of serotonin and dopamine, as well as with a reduction of noradrenaline activity. The researchers note that no previous study had investigated all 3 systems in the same alcohol-dependent individuals.
"Such a design would address the question whether 1, 2, or all 3 systems are affected by excessive alcohol consumption," they write.
The researchers investigated all 3 monoaminergic systems in a group of alcohol-dependent individuals and compared them with the monoaminergic systems in a group of control participants who engaged in nonharmful alcohol consumption.
For the study, investigators examined 70 participants: 19 women (10 alcohol-dependent, 9 healthy control patients) and 51 men (32 alcohol-dependent, 19 control patients). All of the alcohol-dependent participants were recruited from 3 outpatient clinics and were considered high-functioning: 86% had jobs, and 93% had permanent residences. Men and women had consumed the same amount of alcohol during the last year before the investigation; the average alcohol intake during that period was 759 ± 564 g pure alcohol per week.
Central serotonergic neurotransmission was evaluated by the prolactin response to a 40-mg dose of citalopram during a 5-hour period. As demonstrated in previous studies, hormonal responses to serotonin-releasing agents or receptor antagonists are reduced during periods of ongoing drinking, and also during abstinence periods.
Testing revealed that both sexes experienced a 45% decrease in serotonergic neural transmission relative to control participants at 3 hours (P = .007), 4 hours (P < .05), and 5 hours (P < .005) after citalopram administration. However, the effect was seen after only 4 (±3) years of alcohol abuse in women compared with 14 (±8) years in men.
"We expected that long-term excessive alcohol intake would impair the serotonin function in both genders, but [it] was a surprise for us that women´s serotonin function should be equally affected as men's, despite [the fact] that they, on average, had been drinking excessively just for 4 years," Dr. Fahlke said.
According to the authors, the similar loss of serotonergic function in alcohol-dependent women and men despite the disparity in length of alcohol abuse suggests a "telescoping effect" in women.
"The term refers to the later onset and possibly accelerated negative effects that chronic alcohol consumption may have on the brain's structural and functional systems in women," said Dr. Fahlke, noting that even short-term excessive alcohol consumption may be deleterious in women.
Dr. Fahlke explained that it was unlikely that men and women experience a similar alcohol-related decrease in serotonergic function during the first 4 years, and that serotonergic function then stabilizes.
"In an earlier study of ours and unpublished data from the present investigation, we have found a positive correlation between years of excessive alcohol consumption and serotonergic function.
"This means that the longer a person has been drinking, the more reduced is his/her serotonergic function. Based on this finding we assume that there is a gradual reduction in the serotonergic function," Dr. Fahlke said.
Need for Earlier Intervention?
"This research builds upon preexisting work demonstrating that the serotonin system interacts with alcohol drinking to alter future propensity to drink. The differential effect in women compared with men who drink needs further follow-up and validation, as it would stress their need for earlier treatment intervention," Bankole A. Johnson, DSc, MD, PhD, Mphil, FRCPsych, told Medscape Medical News.
Dr. Johnson is a licensed physician and board-certified psychiatrist who is certified throughout Europe and the United States. He currently serves as alumni professor and chairman of the Department of Psychiatry and Neurobehavioral Sciences at the University of Virginia School of Medicine in Charlottesville.
The potential implications for therapy should also be explored, Dr. Johnson added.
"Future research into whether women compared with men that have alcohol dependence respond better to treatment with serotonergic medications would be an interesting follow-up study," he noted.
The study was supported by grants from the Alcohol Research Council of the Swedish Alcohol Retailing Monopoly and the Health and Medical Care Committee of the Region Västra Götaland. Dr. Fahlke and Dr. Johnson have disclosed no relevant financial relationships.
Alcohol Clin Exp Res. Published online July 28, 2011. Abstract
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