Microglia, resident immune cells of the central nervous system, contribute to the surveillance and maintenance of brain tissue. With aging, however, this balance appears to shift.
The study, supported by the United States National Institutes of Health, analyzed postmortem hippocampal tissue from 40 neurologically healthy adults aged 20 to 95. In the 50–75 age bracket, researchers observed a change in the local immune profile, more pronounced than a simple, age-related gradual variation.
Specifically, homeostatic microglia would decrease, while cells displaying more inflammatory signals and characteristics resembling immune cells derived from the blood would increase. The finding suggests a possible shift in the composition of the hippocampal immune compartment.
Clinical Practice Relevance
This finding is of interest because neuroinflammation is involved in neurodegenerative diseases, including Alzheimer’s disease. For the general practitioner, it does not imply new tests or immediate changes in management, but it reinforces attention to preventing cognitive decline starting in midlife.
Keeping cardiovascular and metabolic risk factors in check, staying physically active, maintaining healthy sleep, safeguarding mental health, engaging in cognitive stimulation, and pursuing lifestyle interventions remain central.
Caution in Interpretation
The study was conducted on postmortem tissue and on a small sample: it does not allow establishing a causal relationship with neurodegenerative diseases nor proposing new diagnostic biomarkers.
Nevertheless, it identifies a potential critical biological window between ages 50 and 75, during which the hippocampal immune balance could undergo substantial changes. Further studies will be needed to clarify whether preserving microglial function might contribute to protecting memory and cognitive functions.
Study
Nathan R. Zemke et al., Epigenetic and 3D genome reprogramming during the aging of the human hippocampus. Science 393, eadt8307 (2026).
Abbonati a Karla Miller
