A high-fat diet can cause immune cells in the brain to start destroying connections between neurons.
Naturally, losing these connections is bad for your brain.
The effects of a high-fat diet, however, can be reversed in just two weeks (in mice at least).
Dr Alexis M. Stranahan, who led the study, said:
“Microglia eating synapses is contributing to synapse loss and cognitive impairment in obesity.
On the one hand, that is very scary, but it’s also reversible, meaning that if you go back on a low-fat diet that does not even completely wipe out the adiposity, you can completely reverse these cellular processes in the brain and maintain cognition.”
The study provides some of the first evidence of why fat is bad for the brain.
The root of the problem is that a high-fat diet produces chronic inflammation.
This stimulates the body’s microglia, a part of the immune system, which then get out of control, as Dr Stranahan explained:
“Normally in the brain, microglia are constantly moving around.
They are always moving around their little fingers and processes.
What happens in obesity is they stop moving.
They draw in all their processes; they basically just sit there and start eating synapses.
When microglia start eating synapses, the mice don’t learn as effectively.”
Researchers compared one group of mice getting 10% fat in their diet with another receiving 60% fat.
After 12 weeks the mice on the high-fat diet were obese.
More than that, though, their synapses were getting fried at an increased rate.
The killing of non-functioning synapses is fine normally, Dr Stranahan explained:
“That is one way the developing brain refines itself.
It allows you to keep only those synapses that you need or the synapses you have been using.”
But the problem is that…
“Fat dramatically alters their dynamic.
Instead of doing garbage disposal, they are taking your mailbox, your front door, your kitchen sink and all the stuff that you need, and not doing their job of getting rid of trash.”
Network brain image from Shutterstock