High-sugar diet and obesity linked to brain insulin resistance and neurodegeneration

Researchers at the Fred Hutchinson Cancer Research Centre in the United States have found a connection between obesity and neurodegenerative diseases like Alzheimer's.

They used fruit flies to show that a high-sugar diet, often associated with obesity, can lead to insulin resistance in the brain. This insulin resistance reduces the brain's ability to clear away waste materials from neurons, increasing the risk of neurodegeneration.

The study focused on this connection by using fruit flies, which share some similarities with humans. Previous research had already shown that a high-sugar diet causes insulin resistance in the body's peripheral organs, and this study looked at how it affects the brain. The researchers specifically examined glial cells, which play a role in brain health. They found that the high-sugar diet caused reduced levels of a protein called PI3k in these cells, indicating insulin resistance.

They also looked at the equivalent of microglia in flies, called ensheathing glia, which help remove waste from the brain. These glial cells had low levels of another protein called Draper, showing that their function was impaired. Further experiments revealed that artificially reducing PI3K levels led to both insulin resistance and low Draper levels in the ensheathing glia.

This research, published in the journal PLOS Biology, provides valuable insights into the relationship between obesity, insulin resistance in the brain, and the increased risk of neurodegenerative diseases. These findings could influence the development of therapies to reduce the risk of these disorders in the future.