Nikhil Prasad Fact checked by:Thailand Medical News Team Jun 30, 2026 1 hour, 9 minutes ago
Medical News: A new study is drawing attention to an often-overlooked factor in Alzheimer’s disease—common infections. Researchers have discovered that infections, especially those affecting the lungs, can significantly alter how the brain functions at a genetic level in people with Alzheimer’s.
Study shows infections can alter brain genes and weaken defenses in Alzheimer’s disease
The research involved scientists from the University of Exeter (UK), Maastricht University (Netherlands), Harvard Medical School (USA), University of Bristol (UK), Newcastle University (UK), University of Manchester (UK), University College London (UK), and University of Southampton (UK), alongside several major UK brain banks.
What the Study Looked At
To better understand this link, researchers examined brain tissue from 202 individuals. This group included people diagnosed with Alzheimer’s disease as well as those without it. Some had respiratory infections at the time of death, while others did not.
The focus was on the prefrontal cortex, an area of the brain responsible for memory, decision-making, and behavior. By analyzing gene activity in this region, scientists aimed to uncover how infections influence the Alzheimer’s brain.
Major Genetic Changes Found
The results revealed two very different patterns. In Alzheimer’s patients without infections, 763 genes were found to behave differently compared to healthy individuals. These genes were largely linked to energy production and known pathways involved in neurodegeneration.
However, in those with infections, the number of altered genes dropped to 122—but with a crucial difference. A total of 57 of these genes were unique to Alzheimer’s patients with infections.
These specific genes were associated with blood vessel function, immune regulation, and how brain cells respond to stress. This indicates that infections trigger a distinct biological response rather than simply intensifying existing disease processes.
Brain Defenses Appear Weakened
One of the most concerning findings was that infections may weaken the brain’s immune response instead of strengthening it. The study showed reduced activity in pathways responsible for fighting infections, along with suppressed vascular and circulatory functions.
At the same time, there was an increase in gene activity related to cellular stress and repair mechanisms. This
Medical News report suggests that the Alzheimer’s brain may enter a dysfunctional state during infection, where it struggles to mount an effective defense.
Blood-Brain Barrier May Be at Risk
The research also highlighted potential damage to the blood-brain barrier, a critical protective layer that prevents harmful substances in the bloodstream from entering the brain
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Key cells that maintain this barrier—astrocytes, pericytes, and endothelial cells—were found to be significantly affected during infection. When these cells are disrupted, the barrier may become compromised, allowing inflammatory molecules to enter the brain and potentially accelerate damage.
A Complex Chain Reaction
The findings point to a complex chain reaction triggered by infections in Alzheimer’s patients. These include widespread changes in gene activity, disruption of immune signaling, and impaired blood vessel function.
Rather than simply increasing inflammation, infections appear to reshape how the brain responds at a deeper level. This includes altering cellular communication, metabolism, and structural stability within the brain.
Why This Matters
Respiratory infections are already a major cause of death among individuals with dementia. This study provides a possible explanation, showing that the brain may be less capable of coping with additional stress during infection.
It also raises the possibility that preventing infections—through vaccination or early medical care—could play an important role in slowing disease progression and protecting brain function.
Conclusion
The study offers compelling evidence that infections do far more than trigger temporary illness in Alzheimer’s patients. They appear to fundamentally alter brain biology, weakening immune defenses, disrupting vascular integrity, and shifting gene activity toward a maladaptive state. These insights highlight the urgent need for better infection prevention and management strategies in individuals with Alzheimer’s disease, as controlling infections may help reduce brain damage and improve overall outcomes in this vulnerable population.
The study findings were published in the peer reviewed journal: Neurobiology of Aging.
https://www.sciencedirect.com/science/article/pii/S019745802600120X
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