Do you eat because you are depressed? Or are you depressed because of what you eat?

Depression is very common with an estimated 5-10 per cent of the UK population affected to some degree at any one time. It is more typically thought of as strictly emotional or biochemical, but Nutrition can play a key role, contributing to onset of depression and exacerbating its severity.

New research by Fulton & Sharma (2012) shows that, in addition to causing obesity, excessive consumption of high-fat foods can cause chemical reactions in the brain ultimately leading to depression.

Reward and pleasure centres in the brains of both animals and humans are controlled by a chemical called dopamine. Dopamine enables people to see rewards and take actions to move towards them. Fulton & Sharma showed that mice fed a high-fat diet developed depressive symptoms with changes in the brain's reward and pleasure centres associated with depression.

The fat-fed mice developed high levels of CREB. CREB is a molecule that activates genes involved in brain function including genes that dampen the reward-circuitry. Having high CREB may make the same-old dose of a 'drug', in this instance high-fat food, less rewarding and promote a negative mood state. It seems that if you comfort eat fatty foods to improve your mood you may actually end up feeling worse!

Dr. Fulton draws a comparison with drug addiction whereby a vicious cycle sets in where “food-highs” are used as a way to combat depression. “In a similar way to illicit drugs” says Fulton “continually eating high-fat foods can lead to depression as the 'come-downs' take their toll”.

Whilst Fulton's research focuses on the relationship between high-fat diet and depression, there are plenty of other dietary patterns, including excess sugars, nutrient deficiencies and skipping meals that may contribute to or exacerbate depressive symptoms.

References

Nestler E and Malenka R (2004) Scientific American ;290(3):78-85.

Petra Rattue. (2012, May 28). "Exploring The Relationship Between Depressive Symptoms And High-Fat Diets." Medical News Today. Retrieved from
http://www.medicalnewstoday.com/articles/245910.php.

Sharma S & Fulton S (2012) Diet-induced obesity promotes depressive-like behaviour that is associated with neural adaptations in brain reward circuitry International Journal of Obesity 10.1038/ijo.2012.48.