Only a few weeks ago I looked at a study on fast food consumption and depression, and only a few days ago I talked about a brand new study looking at high fat diets and protection from heart attack damage. And today, weve got another study on high fat diet, this time in mice, and depressive-like behavior. What is the effect of a high fat diet? Well, it appears to be getting more complicated with each new study.
But it this study, at least, it looks like diet-induced obesity might produce depressive-like effects in mice. But how the diet is doing that is not so well defined.
Sharma and Fulton. Diet-induced obesity promotes depressive-like behaviour that is associated with neural adaptations in brain reward circuitry International Journal of Obesity, 2012.
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Several studies in humans have found a correlation between obesity and the development of depression. But its important to keep in mind that correlation is not causation. Many people who become obese also have other things going on (socioeconomic status, family history, comorbid disorders) which can influence the development of depression. In order to determine if obesity itself is causing depression, you first have to deliberately cause obesity in a controlled population.
And this is where mice come in. Using a specialty high fat and high sugar diet, Sharma and Fulton fed up a set of mice for 12 weeks, until they were significantly fatter than control mice. They then looked at behavioral tests for anxiety and depression.
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What you can see above are different behavioral tests. The top two panels represent the elevated plus maze, a plus shaped design with two open arms and two closed arms. Mice prefer to stay in the closed arms of the maze, because they prefer darkness and small spaces. The more anxious a mouse is, the more time he will spend in the closed arms. In this case, the mice fed on a high-fat diet spent more time in the closed arms of the maze.
In the second set of bars, the open field, the findings were similar. The mouse is placed in a large open field. He will usually stay out of the center, preferring the more protected edges and corners. The more anxious a mouse is, the more he will stay to the edges of the field. Again, the high-fat diet mice stayed on the edges more than normal mice suggesting that high-fat diets make mice more anxious.
However, anxiety tests are not depression. For their main depression measure (the bottom set of bars), the authors used the forced swim test, where a mouse is placed in a bucket of water and swims for a few minutes. After a while it will realize it cant get out and begin to float, a sign of behavioral despair. Mice given antidepressants will swim more and float less, and mice showing depressive-like behavior will float more. In this case, the high fat diet mice floated more than control mice, which the authors suggest is depressive like behavior.
See the rest here:
High fat diets and depression: a look in mice
