Already linked to overeating and obesity in adults, a particular genetic feature—the seven-repeat (7R) allele of the dopamine-4 receptor (DRD4) gene—has now been associated with a bent toward fatty snacks and other lip-smacking foods among children, particularly girls. This result, according to researchers, raises the possibility that adult overeating and obesity may originate in food choices observable in the preschool years.
The 7R allele is just one factor in the formation of food-choice patterns. Nonetheless, it is clear that it plays an important role, along with environmental stresses and emotional well-being. To clarify the 7R allele’s role, researchers at McGill University tested 150 four-year-old children by administering a snack test meal. The children were faced with healthy and non-healthy food choices. Mothers also completed a questionnaire to address their child’s normal food consumption and preferences.
The snack test revealed that girls who were 7R carriers ate more fat and protein, and the food-frequency questionnaire showed that 7R carriers of both sexes consumed more ice cream. In addition, the 7R carriers—who, incidentally, were not obese—ate fewer portions of vegetables, eggs, nuts, and whole-bread.
This work, carried out as part of the MAVAN (Maternal Adversity Vulnerability, and Neurodevelopment) project, was announced November 26. It is described in a paper entitled “Association between the seven-repeat allele of the dopamine-4 receptor gene (DRD4) and spontaneous food intake in preschool children,” scheduled to appear in the February 2014 print issue of journal Appetite.
One of the study’s authors, Patricia Silveira, M.D., Ph.D., describes the association between the 7R allele and food intake as follows: “We found that a variation in a gene that regulates the activity of dopamine, a major neurotransmitter that regulates the individual’s response to tasty food, predicted the amount of ‘comfort’ foods—highly palatable foods such as ice cream, candy, or calorie-laden snacks—selected and eaten by the children. This effect was especially important for girls who we found carried the genetic allele that decreases dopamine function.”
An even more important finding was highlighted study leader Michael Meaney, Ph.D., a professor at McGill who co-heads MAVAN: “The amount of comfort food eaten during the snack test in the four-year-olds predicted the body weight of the girls at six years of age.”
According to Dr. Meaney and his team, “blaming” obese individuals for making poor food choices may be unwarranted. “Our research indicates that genetics and emotional well-being combine to drive consumption of foods that promote obesity,” explains Dr. Meaney. “The next step is to identify vulnerable children, as there may be ways for prevention and counseling in early obesity stages.”
The work outlined by Dr. Meaney is part of a broader effort—determining how maternal care influences the expression of genes in offspring, particularly genes that regulate responses to stress. Dr. Meaney and his team examine the molecular mechanisms by which maternal care alters gene expression and the subsequent effects on neuron growth, function, and health.