Gaby
Researchers at Stony Brook University have pinpointed the age when human cognitive function starts to slip.
Analyzing brain scans and tests from 19,300 volunteers, they found cognitive decline begins around age 44 and accelerates until about age 67.
That may not be comforting, but brain aging does slow down again by the time people reach 90.
Why is this discovery important?
The team says these findings could help develop ways to protect brain health later in life.
“Understanding when and how brain aging accelerates gives us strategic time points for intervention. We have identified a critical period in midlife when the brain begins to experience reduced access to energy, but before irreversible damage occurs—essentially, it’s a breaking point before a breakdown,” said neurobiologist Liliana Muhika-Parodi, the study’s lead author.
Her team identified neuronal insulin resistance as a possible underlying cause. They found that insulin becomes less effective on neurons with age, so neurons take up less glucose for energy, which disrupts brain signaling.
So the researchers suggest restoring or replacing neuronal energy sources could slow brain aging and offer another treatment option for neurodegenerative diseases.
“In middle age, neurons experience metabolic stress from a lack of fuel; they struggle but remain viable. Providing alternative fuel during this critical period may help restore function. In later years, however, prolonged fuel deprivation can trigger a cascade of other physiological effects that make intervention less effective,” Muhika-Parodi said.
Promising experiment with ketones
The researchers tested their idea in 101 people who were given ketone supplements. Ketones are molecules the body can use as an alternative energy source when glucose supply or production is limited. They can also improve neurons’ insulin sensitivity and help correct metabolic disturbances.
After taking the supplements, participants’ cognitive decline stabilized. The largest benefits appeared in middle-aged people (ages 40–59), suggesting timing will be crucial for this type of treatment.
Neurobiologist Botond Antal, a co-author of the study, said, “Instead of waiting for cognitive symptoms to appear, which may not show up until significant damage has occurred, we can potentially identify at-risk individuals using neurometabolic markers and intervene during this critical window.” The study appeared in the journal PNAS.
