UPTON, NY— Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have produced new evidence that brain circuits involved in drug addiction are also activated by the desire for food. The mere display of food — smelling and tasting favorite foods without actually eating them — causes increases in metabolism throughout the brain. Increases of metabolism in the right orbitofrontal cortex, a brain region that controls drive and pleasure, also correlate strongly with self-reports of desire for food and hunger.
“These results could explain the deleterious effects of constant exposure to food stimuli, such as advertising, candy machines, food channels, and food displays in stores,” says Brookhaven physician Gene-Jack Wang, the study’s lead author. “The high sensitivity of this brain region to food stimuli, coupled with the huge number and variety of these stimuli in the environment, likely contributes to the epidemic of obesity in this country.” The study appears in the April 2004 issue of NeuroImage.
This reaction is an example of an evolutionary adaptation that is no longer adaptive in modern environments. While calorie malnutrition was a major cause of death for almost all of human history in many parts of the world today calorie malnutrition is rarely a cause of death. Human brain reactions to food are therefore more often maladaptive than adaptive. Humans need biotechnologies that will help them adapt themselves to the new environments they have created for themselves and our response to plentiful food is a major cause of the need for adaptive biotechnologies.
Previous Brookhaven work has shown similarities between the brains of food addicts and drug addicts.
Brookhaven scientists have conducted previous research showing that the right orbito-frontal cortex is involved in compulsive behaviors characteristic of addictive states, and that this brain region is activated when addicted individuals crave drugs such as cocaine (see related story). They have also shown that food stimulation, as done in this study, increases levels of dopamine, a neurotransmitter involved in pleasure and reward, in the brain’s dorsal striatum (see related story). Additionally, to better understand the relationship of the dopamine system to obesity, they looked at the brain circuits of obese individuals and found that, like drug addicts, these individuals had fewer dopamine receptors than normal control subjects (see related story).
In their most recent research the Brookhaven scientists used positron emission tomography (PET) scans to study the response of normal people to food and found that food exposure increases metabolism in almost all major areas of the brain.
The researchers found that food stimulation significantly increased whole brain metabolism. Metabolism was higher in all regions of the brain examined, except for the occipital cortex, which controls vision and would not be affected. The areas most affected were the superior temporal, anterior insula, and orbitofrontal cortices. Food stimulation also resulted in increases in self-reports of hunger and desire for food. Increases in metabolism in the right orbitofrontal cortex were the ones that were most significantly correlated with increased reports of hunger.
People suffering from food addiction problems would benefit from removing reminders about food from their environment. That is hard to do because of the sheer number of sources of food reminders ranging from street signs of restaurants, billboards, advertisements in magazines, on radio and on TV, TV portrayals of people eating, and the presence of a kitchen in most dwellings. Still, there are ways to reduce one's exposure to food smells and images. For instance, remove all visible food in a house by having no fruit basket on a table and no food cans visible on shelves. One could listen to commercial-free satellite as a way to avoid food ads. Also, avoid looking at the types of magazines that have a lot of food ads.
Technology may eventually provide greater control over one's environmental stimuli. For instance, some web sites already provide ways to configure personalized ad profiles of areas of interest. Digital TV advances ought to allow one to separate what show one is going to watch from what ads one sees. Perhaps some day TV channels will let one specify the types of ads one wants to watch and thereby provide a way to avoid, say, food or alcohol ads.
In the longer run food addiction problems will be controllable by drugs that will suppress appetite. Also, it will eventually become possible to turn up the amount of brown fat cells that burn off excess calories.
Gene-Jack Wang has done other interesting work about addiction. Wang and his colleagues previously showed that methamphetamine-induced brain damage is long-lasting. For details see my previous post Partial Recovery From Methamphetamine-Induced Brain Damage.
It will be interesting to see whether the lower dopaminergic neuron levels in the right orbito-frontal cortex of people with addiction problems in all cases precede the addiction or are caused by the addiction or a mixture of both. Also, are obese people more prone to drug addictions? Given that some obese people feel motivated to take methamphetamine to suppress appetite separating out the causes and effects is difficult.
|Share |||Randall Parker, 2004 April 20 10:30 AM Brain Addiction|