Fatty foods might be comforting as we eat them, but a recent study from by the Universite de Montreal found that a diet rich in high-fat foods is linked to anxiety and depression in mice.

High-fat foods cause us to feel good momentarily as they “light” up parts of our brain, but lead researcher Stephanie Fulton says that foods rich in fat “can actually cause chemical reactions in the brain in a similar way to illicit drugs, ultimately leading to depression as the ‘comedowns’ take their toll.”

Fulton said that while recent studies are revealing that obesity is linked to a higher risk of depression, the underlying biological mechanisms between the two remain unknown. The Universite de Montreal study investigates whether a high-fat diet affects the brain’s emotion and reward circuits:

“For the new study, the researchers studied mice already prone to obesity. One group was fed a diet high in fat, particularly saturated fat, the other low-fat chow. After 12 weeks, the rodents were given a series of behavioral tests, including ‘anxiety’ tests measuring how they react to a new environment. Stressed animals tend to freeze, or run off to a corner, rather than explore. Mice given the high-fat diet were much less active, avoided open areas and did little exploring. In a swim test used to measure ‘behavioral despair’ — a test also widely used by drug companies to screen new anti-depressants — mice had to swim in a glass cylinder filled with water for six minutes. ‘Animals that give up quickly — they stop swimming and just float and stop trying to pull themselves out of the beaker — that’s [a sign of] self-helplessness,’ Fulton said. Mice on the high-fat diet ‘actually gave up’ and attempted fewer escapes, she said. When the researchers studied the rodents’ brains, they found higher levels of corticosterone, a stress hormone. They also saw a difference in the expression of proteins responsible for signaling among neurons in areas of the brain regulating emotions and reward.”

Comments Fulton, “In the short-term, high-fat food feels comforting, but in the long-term, and with increasing adiposity (fat mass), it is having negative effects on mood. We know that diet is a large contributor to the obesity epidemic throughout the world.”

Source: PsychCentral