A new study analysed networks in the brains of people of different ages and found that brain aging appears to accelerate at certain points in life. (Image credit: Eugene Mymrin/Getty Images)
The study found that the human brain suddenly begins to age significantly faster at around age 44, with peak aging rates reached by age 67.
The work, published March 3 in the journal PNAS, appears to confirm the findings of another study recently reported by Live Science, which analyzed aging using blood samples and found periods of accelerated aging around age 44 and 60.
A new neuroscience study has also found that brain aging is linked to insulin resistance, in which cells require more insulin than normal to control blood sugar levels. What’s more, it found early signs that ketone supplements may offer some protection against certain aspects of brain aging.
Ketones are substances in the body that act as an alternative energy source by replacing sugars. So if the brain is aging due to a lack of sugars, ketones could help make up for the shortfall, the team suggested.
However, further research will be needed to confirm this hypothesis.
Early Signs of Brain Aging
The researchers used four existing brain scan datasets that included data from a total of 19,300 people aged 18 to 90. To analyze the connections between different brain regions, the team used two types of scans: functional magnetic resonance imaging (fMRI), which measures blood flow, and electroencephalogram (EEG), which records electrical activity between neurons in the superficial layers of the brain.
In these scans, the scientists looked for signs that blood flow and electrical activity between brain regions had either disappeared or become inconsistent, indicating a breakdown in the connectivity between network nodes. They had seen this network breakdown as a sign of aging in previous studies that assessed the effects of diet on the brain. Similar disruptions are also seen in neurodegenerative diseases associated with aging, and the extent of these disruptions typically reflects a person’s overall level of aging.
In their analysis, the researchers found that the brain begins to age faster at around age 44, and the rate of aging peaks around age 67. After that, the brain's aging process begins to slow down until the rate stabilizes around age 90.
“We didn't expect that the effects could show up as early as the 40s,” senior study author Lilianna Mujica-Parodi, a neuroscientist at Stony Brook University, told Live Science.
Sugars vs Ketones
The network disruptions they observed were similar to changes previously documented in the brains of people aged 50 to 80 with type 2 diabetes. Mujica-Parodi and her team wondered whether the changes might be due to the neurons’ poor response to insulin, the hormone responsible for transporting sugar from the blood into cells.
The effect isn’t limited to people with diabetes. “Eighty-eight percent of North Americans have at least one detectable sign of insulin resistance,” said Dr. Luis Adrian Soto-Mota, a metabolism researcher at the Monterrey Institute of Technology in Mexico who was not involved in the study but has worked with the team before.
After examining all the brain scans, including data from people with and without insulin resistance, the team found that people in their 40s with high blood sugar levels had faster brain aging than the same older people without signs of insulin resistance.
Moreover, across all the scans, certain areas of the brain aged faster than others, prompting the researchers to wonder whether these areas might be more sensitive to insulin. The protein GLUT4 is known to rely on insulin to move sugar into cells. So the team turned to the Allen Brain Atlas, which includes data on GLUT4 gene activity, and found that rapidly aging areas were indeed more dependent on GLUT4.
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