Is it really true that adiposity can affect the way we control our goal directed behavior?
Health problems associated with being overweight
Weight problems are reaching epidemic proportions worldwide, with approximately 60% of American adults and 50% of European Union adults (in 46 of the 53 countries) being overweight or obese – rates that are expected to further increase over the next years. This increase represents a serious and costly challenge to public health given the well-known physical consequences associated with obesity, including type 2 diabetes, hypertension and other cardio-vascular diseases, stroke, several forms of cancer, and depression.
Being overweight enhances distraction
Besides the physical consequences are there any cognitive consequences associated with being overweight?
Together with my colleague Lorenza Colzato, we tried to answer this question by comparing a group of people with a normal weight (Body mass index-BMI: 18-25) with a group of overweight people (BMI: 25-30) on the Simon task—in which participants have to ignore irrelevant information on a computer screen. We found that overweight people were more distracted by the irrelevant information than people with a normal weight. This means that adiposity seems to damage interference control, the ability of suppressing irrelevant information.
Even though the task we used to diagnose interference control in overweight people is rather artificial, the deficit itself is likely to affect everyday behavior. Many real-life situations require the ability of suppressing distraction. This is particularly obvious for examples like traffic behavior, where stopping to walk or to drive is necessary when the traffic light turns from green to red, or when passengers, animals, or vehicles are suddenly crossing the street.
Mechanism of action
What are the neurobiological underpinning of our findings? The neurotransmitter dopamine seems to play a pivotal role. It has been found that, in overweight individuals, BMI correlates negatively with striatal dopamine D2 receptor levels, and that lower-than normal striatal D2 receptor availability is associated with reduced metabolic activity in the same brain regions which are crucial for the ability to suppress irrelevant information.
Want to know more? Please read our article published in the journal Appetite:
Sellaro, R., & Colzato, L. S. (2017). High body mass index is associated with impaired cognitive control. Appetite, 113, 301-309.