High-fat diet during adolescence increases impulsive behaviors in adult rodents

For adults, a diet high in saturated fats and added sugar has been linked to impulsivity and poor self-control. But what role, if any, does diet play in adolescent psychological development?

Researchers report in ACS Chemical Neuroscience that adolescent rodents fed a high-fat diet showed poor control during motor inhibition tasks and conservative decision-making in gambling scenarios as adults. This information could provide insights into human development.

Diet is one of many factors—like sleep, exercise and substance use—expected to affect an adolescent’s cognitive development and reward-seeking behavior. Previously, researchers collected evidence that supports the importance of sleep and exercise on behavioral development, but there is limited data about the effects of specific patterns of eating. So, Santiago Mora and colleagues designed experiments to look at the potential influences of a high-fat diet during adolescence on the actions and choices of adult rats.

For the experiments, Mora’s team fed 20 young rats a high-fat diet of cheesecake (cheesecake rats) and another 20 a nutritionally balanced chow diet (chow rats). When the rodents reached adulthood, the researchers trained all 40 to perform multiple tasks, including a gambling scenario. These attention and inhibitory-control tasks allowed the researchers to evaluate the animals’ abilities to manage impulsive and compulsive actions and make safe decisions.

Task evaluations revealed that adult cheesecake rats prematurely responded to visual cues (i.e., jumping the gun to get a tasty snack), which the researchers say is evidence of increased impulsive actions. However, the adult cheesecake rats exhibited less risky decision-making by opting for safer but smaller rewards during gambling scenarios (i.e., no high rolling in casinos) than the adult chow rats.

In additional tests, the researchers identified genetic differences between the cheesecake and chow rats’ prefrontal cortices (one of the parts of the brain that control behavior and personality) and gut metabolism biomarkers.

Briefly, the cheesecake rats exhibited altered function of the mesolimbic pathway—the so-called reward pathway—in their brains and had modified levels of fatty acids in their guts linked to neurological and behavioral outcomes. The results suggest that a high-fat diet during adolescence could interfere with brain development and affect neurobehavioral outcomes in adulthood.

The researchers say that their data show a high-fat diet in adolescence can provoke long-term changes in impulsive behavior in rats, but they recognize more research is needed to “disentangle the specific mechanisms underlying these intriguing effects.”