Friday, December 21, 2007

Genetic Anomaly Linked To Seasonal Binge Eating -- Arehart-Treichel 40 (3): 46 -- Psychiatr News

Genetic Anomaly Linked To Seasonal Binge Eating -- Arehart-Treichel 40 (3): 46 -- Psychiatr News

Genetic Anomaly Linked To Seasonal Binge Eating
Joan Arehart-Treichel

A gene variant involved in dopamine transmission may be linked to a binge-eating syndrome in seasonal affective disorder. The finding may point toward detection and prevention strategies.

Although only a small percentage of North Americans experience full-blown seasonal affective disorder—about 1 percent of Americans and 2 percent of Canadians—a much larger percentage—between 10 percent and 15 percent—report depression accompanied by increased eating and weight gain during the fall and winter. Moreover, of this larger percentage, a substantial number also engage in binge eating.

Now a gene variant linked to seasonal affective disorder binge eating appears to have been identified. It is a variant of the dopamine-4 receptor gene called the seven-repeat allele.

The study was headed by Robert Levitan, M.D., an associate professor of psychiatry at the University of Toronto. Results appeared in the November 2004 Biological Psychiatry. "Pending replication in other samples," the scientists wrote, "these results point to a genetic vulnerability factor that could help in the early identification and treatment of women at higher risk for seasonal weight gain associated with binge-eating behavior."

The dopamine-4 receptors appear to be active in limbic areas of the brain involved in cognition and emotion. There are seven known variants of the gene that codes for these receptors; the seven-repeat allele is one. Between 25 percent and 35 percent of Caucasians and up to 65 percent of some American-Indian populations possess at least one copy of this version.

Levitan and his colleagues previously found a link between the seven-repeat allele and obesity in women with seasonal affective disorder, implying that the allele might bring about weight gain via binge eating. They then undertook another study to investigate this hypothesis.

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