Drinking among some alcoholics may be a way of increasing the body's levels of the brain chemical serotonin, according to recent study findings, and low levels of this chemical may also cause them to crave sweets. Carbohydrate craving may be an important clue to developing more diversified treatments for alcohol-dependent subjects. The team reports that diet has a significantly different effect on alcoholics who have high cravings for carbohydrates compared with those who report lower levels of cravings.

Alcohol and carbohydrates have both been shown to increase levels of serotonin in the body, the researchers explain. Low levels of this chemical can lead to depression, anxiety, aggression, and sleep problems.

After a high-carbohydrate diet, alcoholics showed significantly greater increases in symptoms of depression than the individuals not given the high carbhoydrate diet. Depression scores after a high-protein diet did not change for any of the groups. The authors point out that sweets seem to have a paradoxical effect on patients with high levels of craving: they appear to provide a brief improvement in mood followed by a longer period of mood worsening. Similar findings have been reported in patients with depression and bulimia.

In addition, carbohydrate-craving alcoholics reported significantly more craving for alcohol during both types of diets than the other two groups, the findings indicate. This group also showed more symptoms of personality disorder than non-craving alcoholics.Before the diet phase of the study, the alcoholic patients showed lower levels of serotonin activity in the blood. The high-protein diet, however, affected the two groups of alcoholics differently. This diet increased serotonin activity in carbohydrate-craving patients, while it decreased serotonin activity in non-craving patients and in controls.

Moorhouse and colleagues suggest that alcoholics with strong cravings for carbohydrates may form a distinct subgroup of patients with this disease. This type of alcoholic may drink to increase their serotonin levels, and may increase their intake of carbohydrates if not drinking, to achieve the same effect. Abnormal (serotonin) response to diet is specific to high carbohydrate-craving subjects," the authors point out. "This response may reinforce alcohol and/or food intake and perpetuate substance abuse. High carbohydrate craving alcohol-dependent subjects are potentially at greater risk for relapse than low carbohydrate craving alcohol-dependent subjects.

Alcoholism: Clinical and Experimental Research May 2000;24:635-643