Alcoholics likely have reduced levels of serotonin, a neurotransmitter believed to regulate sleep, dreaming, mental illness, craving, and eating. Because alcohol increases serotonin levels, some researchers speculate that alcohol-dependent individuals are using alcohol to self-medicate their reduced serotonergic function, bringing it up to a ‘normal’ level. Like alcohol, carbohydrates increase serotonin levels. A study in the May issue of Alcoholism: Clinical & Experimental Research may have found a sub-group of alcoholics who self-medicate low levels of serotonin with carbohydrates when they’re not drinking.
"More and more, we appreciate that alcoholism and alcohol problems are complex disorders that involve physiological and psychological factors," said David J. Drobes, assistant professor of psychology at the Medical University of South Carolina. "Research is now beginning to uncover specific genetic factors and neurobiological mechanisms that contribute to alcoholism. This study helps us to understand how disturbances in one of the important neurochemical systems, the serotonergic system, may be related to increased alcohol craving among certain alcoholics."
"We know that impaired serotonin function can lead to depression, anxiety, aggression, and sleep problems," said Mona Moorhouse, clinical dietician at the Royal Ottawa Hospital and lead author of the study. "Many anti-depressants will enhance serotonin, for example. In addition, we know that serotonin affects food intake, specifically, carbohydrate intake." Moorhouse’s study was prompted by observations of patients attending a local addiction treatment center; about 50 percent of those in treatment for alcoholism reported extreme cravings for carbohydrates, particularly sweets, upon abstinence from alcohol. Moorhouse called this a "biological drive."
Researchers examined the response of a distinct group of alcoholics - those who reported high cravings for carbohydrates - to two different diets: a high sugar diet, and a high protein diet. When placed on a diet high in sugar, these alcoholics became more depressed than other study participants. A diet high in protein increased the serotonin activity of this select group, whereas it reduced it in the other study participants. In addition, those alcoholics who reported high cravings for carbohydrates also reported that they were likely to crave alcohol when under stress.
"This finding is consistent with studies that show a strong relationship between various moods and craving for alcohol," noted Drobes. "Negative moods - such as stress, anger and depression - are major cues for craving. People tend to drink more often when they’re in good moods or bad moods, relative to a neutral mood, but there’s a particularly strong relationship between bad moods and drinking. Social settings are a major environment for drinking among people who don’t have a problem with alcohol, but alcoholics tend to drink more when they’re depressed, stressed, or angry."
"What’s interesting about this study," said Moorhouse, "is that in terms of their biochemistry, high carbohydrate craving addicts responded very differently to diet as compared to those with no food cravings. There’s something unique about this group. They have an abnormal response to diet; perhaps they have an abnormal response to alcohol too. This study’s findings provide us with a little bit more insight into this dysfunction, and may enable future research to look at treatment strategies."
Drobes concurs. "Because of this study, we now know more about how serotonin is disrupted in certain kinds of alcoholics. This may lead to improved development of medication that is not only designed to treat the disorder of alcoholism, but may identify which alcoholics are going to benefit from which medication."
"What we still don’t know," added Drobes, "is whether this disregulated serotonergic system is a predisposing factor for alcoholism or is it an effect of alcoholism? In other words, are some people born with a chemical imbalance that primes them to become alcoholics at some point in their lives? Or does someone’s serotonergic system first become disregulated after excessive drinking? It’s the chicken or egg question, and an interesting area for future research."
Funding for this Addiction Science Made Easy project is provided by the Addiction Technology Transfer Center National Office, under the cooperative agreement from the Center for Substance Abuse Treatment of SAMHSA.
Articles were written based on the following published research:
Moorhouse, M., Lob, E., Lockett, D., Grymala, J., Chudzik, G., & Wilson, A. (2000, May). Carbohydrate craving by alcohol-dependent men during sobriety. Alcoholism: Clinical and Experimental Research, 24(5), 635-643.
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