A brain enzyme may help memory hold up in old age, mouse study suggests

Most of us know the moment: a name that will not come, keys that are not where we left them. Some people keep a sharp memory into their eighties, and others do not. A new study on age-related memory loss suggests part of the difference may lie in one enzyme the brain makes to protect itself. The work is mostly in mice, and it is not a treatment.

The study appeared in Nature Neuroscience on 15 October. It points to a natural defence that rises with age, and that seems strongest in older people whose thinking stays clear. That makes it a useful clue to one of medicine’s oldest questions: why memory loss and aging affect people so differently.

How one enzyme in the mouse hippocampus became the lead

The team is from Mass General Brigham in Boston. Cinzia Vicidomini is the first author and Amar Sahay the senior author.

They looked for genes that switch on when the hippocampus, the brain’s memory hub, starts losing synapses. Synapses are the links between nerve cells. One gene stood out: Pla2g2f. It makes a phospholipase, an enzyme that cuts fats, and its job in the brain was unknown.

Its levels rise in the hippocampus with age and with brain inflammation. To test what it does, the team turned it off in memory-related nerve cells of middle-aged mice. They also raised it in aged and middle-aged mice. The results ran in a clear direction:

• Less enzyme, more damage. Synapse loss got worse. The brain’s immune cells, called microglia, turned more inflammatory. New nerve cells matured poorly, fat droplets built up, and memory suffered.
• More enzyme, more protection. It guarded against many of these changes and kept memory working in aged mice.
• Timing mattered. Raising it in middle age, before major decline, changed the course of later memory loss.

In human microglia grown from stem cells, the enzyme also cut the build-up of fat droplets and stored cholesterol.

The human link is a pattern, not proof

The team also studied two large existing collections of brain gene data from donors who had memory tests in life. Activity of the human version of the gene rose with age. It was highest in “resilient” older people, whose thinking stayed intact despite amyloid-beta deposits, a hallmark of Alzheimer’s.

That fits the mouse results, but it is a correlation. It does not show the enzyme caused the resilience. In our reading, this adds to research on Alzheimer’s cognitive resilience: a candidate, not an answer.

Much is still unknown. No sources we found gave sample sizes or effect sizes, so we describe the results only in words. We found no comment from independent scientists. The mouse method for raising the enzyme is a lab tool, not a ready human approach. The authors say more studies are needed to know whether raising it in patients could be done safely.

If age-related memory loss worries you or your family

Can memory loss from aging be prevented? Not with this enzyme, at least not yet. There is no pill, supplement or trial for age-related memory loss based on it, and no product can honestly claim one.

What does help is well known. Mayo Clinic and Consumer Reports point to regular exercise, a healthy diet, sleep, blood pressure control and staying social. Hearing care matters too. If a parent’s forgetfulness is getting worse, a doctor’s visit is still the right first step.

Do not mix this up with GPLD1, a different, exercise-linked enzyme from the liver that made news earlier this year.

A careful clue that earns attention, not yet hope

On balance, this is solid early science. It finds a protective system, tests it both ways in mice and checks it against human brain data. The idea that the brain fights back, and that the fight weakens in some people, is a hopeful frame for cognitive decline with age.

The limits are just as plain. Mice are not people, the human data shows a link rather than a cause, and key numbers are not public in the coverage. Like the recent brown fat study, where a blood-pressure pill raised brown fat in mice, the gap from mouse to patient is long.

The likelier path is slow. This finding gives labs a clear target to test, and it may take years to learn whether it helps people.

The team says it is now looking for safe ways to raise the enzyme. The next study to watch is one that tries it beyond the mouse.