A new study has found that a high fat diet completely alters the behaviour of immune cells within the brain, causing a reduction in the number of connections between neurons.
While we all know that eating a high fat diet is bad for us, and it has been previously shown that diets high in fat are associated with age-related cognitive decline, the specific mechanisms involved have not been well studied.
A recent study has investigated the effects of a high fat diet and related obesity on cellular signalling within the brain. Researchers from the Department of Neuroscience and Regenerative Medicine, Medical College of Georgia, Augusta, United States, used a mouse model to study these effects. They first fed the mice either a high-fat diet or a low fat diet, for three months. They found an increase in inflammatory markers in the brains of the mice after three months on a high fat diet. However, they also found that the microglia, (immune cells present in the brain), began to change their behaviour when mice were fed a high fat diet. Rather than moving around as normal, they became stationary and began to ‘eat’ the synapses (the connections between neurons), resulting in an overall reduction in synapses within the hippocampus.
As a result, the mice on the high fat diet were also found to have an impairment in hippocampus-dependent memory, signal transmission between synapses.
The researchers then switched a group of mice from the high fat diet to the low fat diet. By doing this, the researchers found that the brain changes were reversed after 2 months on a low fat diet. The results demonstrate that while the brain changes due to a high fat diet are detrimental, there is also the potential to reverse the negative effects.
Hao, S, Dey, A, Yu, X, Stranahan, AM. “Dietary obesity reversibly induces synaptic stripping by microglia and impairs hippocampal plasticity” Brain, Behaviour & Immunity doi:10.1016/j.bbi.2015.08.023
Written by Deborah Tallarigo, PhD