Comfort food for the brain

AH DOPAMINE, THAT FASCINATING NEUROTRANSMITTER linked to the brain’s reward pathways and implicated in everything from addiction to Parkinson’s disease.

In a report published in the academic journal Appetite, researchers at the McGill-affiliated Douglas Mental Health University Institute say they are the first to connect a specific dopamine suppressing gene with a predisposition to childhood obesity.

Michael J. Meaney, James McGill Professor in the departments of Psychiatry and Neurology and Neurosurgery, led a team of researchers who administered a snack test — consisting of foods ranging from eggs, apples and baked beans to Frosted Flakes, white bread and a chocolate chip muffin — to 150 four-year-old children. The children’s mothers also filled out questionnaires addressing daily food intake and preferences.

Neurological studies suggest that our bodies’ levels of dopamine can affect eating behaviour, and research in obesity studies has shown that sweet and fatty foods can trigger a greater release of dopamine, inducing more significant feelings of enjoyment and pleasure.

Meaney and his colleagues performed DNA analyses on the children to screen for the seven repeat allele (7R) of the dopamine-4 receptor gene (DRD4), which has been shown to decrease dopamine function and which has also been associated with increased eating behaviour and obesity, particularly in females.

The researchers found that girls who carry the 7R allele ate more fat and protein, as well as less vegetables, nuts and whole wheat bread, than non-carriers, suggesting that the allele influences food choices from an early age.

“Our research indicates that genetics and emotional well-being combine to drive consumption of foods that promote obesity,” Meaney said. “The next step is to identify vulnerable children, as there may be ways for prevention and counselling in early obesity stages.”