You probably know that forgetful moment when a familiar name slips away. Most of us accept it as part of growing older. Scientists are now starting to zero in on what might be driving it.
A team led by neuroscientist Lige Leng at Xiamen University has traced one such driver to a protein called Menin. It naturally drops with age in a small brain region called the hypothalamus, the body's control center.
In a study published in PLOS Biology, restoring Menin in old mice reversed several signs of aging within about 30 days. Skin thickened, bone mass rose, and the animals performed better on learning, memory and balance tests.
How a brain hub protein shapes memory
The hypothalamus is a pea-sized region deep in the brain that keeps metabolism, hormones and body temperature in check.
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Leng's team found that when Menin drops in a specific cluster of these neurons, inflammation rises. That shift seems to ripple outward and nudge the body toward aging.
One of Menin's jobs is to help the brain make D-serine, an amino acid the brain uses as a chemical messenger for learning and memory. When Menin drops, D-serine supply falls too.
The amino acid that eased memory loss in old mice
When Leng's team added D-serine to the drinking water of aged mice for three weeks, the animals learned faster and remembered better. The amino acid did not fix the skin and bone changes, which suggests Menin shapes aging through more than one route.
In humans, the evidence is far thinner. A small randomized trial from 2016 in Oncotarget tested D-serine against a placebo in 50 healthy older adults. Participants improved on one measure of spatial learning but showed no clear change on other cognitive tests or mood scores.
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Why doctors are not ready to recommend D-serine
A 2025 study in Cellular and Molecular Life Sciences sounded a warning. In mice engineered to develop Alzheimer's features, extra D-serine early in the disease disrupted brain signaling. Removing the enzyme that makes D-serine reduced some later cognitive problems.
That contrast matters. D-serine may help a healthy aging brain and hurt one already on an Alzheimer's path. High doses have also raised kidney safety questions in animal work, and long-term safety in people is not established.
For now, Menin and D-serine are leads for scientists, not pills to buy. Anyone worried about memory changes should talk to a doctor rather than reach for an amino acid supplement.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.