Dopamine Activity in Brain May Play Role in Obesity

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Obese adults may be more susceptible to environmental food cues than lean adults due to differences in brain chemistry that make eating more habitual and less rewarding, according a new study

Juen Guo, PhD, of the National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, and colleagues conducted a study in 43 men and women with varying amounts of body fat. Study subjects followed the same eating, sleeping, and activity schedule.

A questionnaire was used to determine their tendencies to overeat in response to an environmental trigger. PET scans were also used to evaluate the site in the brain where dopamine was able to act.

The obese participants tended to have greater dopamine activity in the habit-forming region of the brain than their lean counterparts, and less activity in the region controlling reward, the researchers reported in Molecular Psychiatry. This might help explain how the obese are more drawn to overeat in response to food triggers and simultaneously make food less rewarding to them.

A causal relationship between habit formation, reward, dopamine activity, eating behavior, and obesity was not established. Researchers note further research will study dopamine activity and eating behavior in people over time with changing diets, physical activity, and weight.

Dopamine Activity in Brain May Play Role in Obesity
Dopamine Activity in Brain May Play Role in Obesity

The obesity epidemic is believed to be driven by a food environment that promotes consumption of inexpensive, convenient, high-calorie, palatable foods. Individual differences in obesity susceptibility or resistance to weight loss may arise because of alterations in the neurocircuitry supporting food reward and eating habits. In particular, dopamine signaling in the ventromedial striatum is thought to encode food reward and motivation, whereas dopamine in the dorsal and lateral striatum orchestrates the development of eating habits.

We measured striatal dopamine D2-like receptor binding potential (D2BP) using positron emission tomography with [18F]fallypride in 43 human subjects with body mass indices (BMI) ranging from 18 to 45 kg m2.

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