The human brain needs over 20% of the body’s energy to function, and it gets this from metabolizing either glucose or ketone bodies.

Hypometabolism occurs when brain cells cannot use glucose as an energy source.

The brain is vulnerable to changes in metabolism.

People with Alzheimer’s disease often experience a severe drop in the brain’s glucose metabolic rate, and the extent of this reduction is associated with the severity of their illness.

Alzheimer’s disease is the most common form of dementia. According to the World Health Organization (WHO), approximately 50 million people globally have dementia, and about 60 to 70% of these have Alzheimer’s disease.

While scientists have been unable to pinpoint why the brain cells stop metabolizing glucose at this point, previous research has shown that a drop in glucose metabolism appears early before Alzheimer’s symptoms develop.

In this study into a low carb diet, researchers from the United States and the United Kingdom used the stability of this communication network between brain regions as a way to measure age-related changes in the brain.

They set out to investigate when these changes start and whether a change in a person’s diet from one rich in glucose to ketones could affect the communication between these brain regions.

To determine when these changes to neural stability emerge, the researchers used two large-scale functional magnetic resonance imaging (fMRI) datasets. One dataset came from the Max Planck Institut Leipzig in Germany, and the other from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) in Cambridge, UK. The datasets contained brain scans of nearly 1,000 adults across their life-span (ages 18 to 88).

This type of brain scan measures the stability of brain networks, defined as the brain’s ability to sustain functional communication between its regions.