Alzheimer’s immune dysfunction may extend far beyond the brain, according to new research revealing an unexpected role for bone marrow in disease progression. Scientists found that Alzheimer’s disease disrupts the production of certain immune cells in bone marrow, potentially preventing protective monocyte-derived macrophages from reaching the brain. In an established mouse model of amyloid disease, blocking the responsible inflammatory signaling pathway restored healthier immune-cell production and reduced several manifestations of disease.
The findings, published September 8, 2026, in Nature Neuroscience, strengthen a growing view that Alzheimer’s should not be understood solely as a disorder confined to the brain. Systemic immune changes may also influence how the disease develops and progresses.
Alzheimer’s Immune Dysfunction Reaches Bone Marrow
The study focused on myelopoiesis, the biological process through which bone marrow produces myeloid immune cells, including monocytes.
Previous research has suggested that monocyte-derived macrophages can travel from the circulation into diseased brain tissue and support local immune defenses when resident microglia are unable to adequately manage Alzheimer’s-related pathology. Experimental increases in these cells have been associated with reduced inflammation, less pathology and slower cognitive deterioration in mouse models.
The new research asked why these potentially beneficial immune cells do not naturally enter the Alzheimer’s brain in greater numbers.
Researchers discovered that their production was already being disrupted at the bone marrow level.
Alzheimer’s Immune Dysfunction Alters Monocyte Development
In the 5xFAD mouse model, which develops rapid amyloid accumulation and is widely used to study aspects of Alzheimer’s pathology, hematopoietic stem-cell behavior and monocyte development were altered.
The researchers identified a strong type I interferon, or IFN-I, signature within the affected bone marrow. This inflammatory signaling appeared to interfere with normal differentiation of monocytes before they could leave the marrow and enter circulation.
Importantly, the researchers did not observe the phenomenon only in mice.
They also identified a similar altered phenotype among circulating monocytes from people with Alzheimer’s disease, providing an important human connection to the experimental findings.
That does not establish that the same mechanism causes Alzheimer’s progression in humans, but it supports further investigation.
Type I Interferon Becomes Key Target
Type I interferons are important components of the immune system and help coordinate responses to infections and cellular stress.
Persistent or inappropriate activation, however, can contribute to chronic inflammatory conditions.
The researchers investigated whether excessive IFN-I signaling was responsible for the abnormal bone marrow response in Alzheimer’s.
They tested two approaches in 5xFAD mice.
One involved using neutralizing antibodies to block type I interferon signaling. The other involved replacing bone marrow with marrow lacking IFNAR1, a receptor required for the interferon response.
Both approaches provided evidence that the pathway was mechanistically important.
Alzheimer’s Immune Dysfunction Improved After Blockade
Blocking IFN-I signaling restored more normal myeloid-cell production and corrected abnormal monocyte characteristics.
The intervention was also accompanied by greater recruitment of monocyte-derived macrophages into the brain and improvement in Alzheimer’s-related pathology in the mouse model.
These results suggest that the peripheral immune system may represent a therapeutic target rather than simply a secondary consequence of brain disease.
However, the findings should not be interpreted as evidence that interferon-blocking drugs are ready to treat Alzheimer’s patients.
The therapeutic experiments were conducted in mice, and systemic interferon signaling plays important roles in immune defense. Any attempt to manipulate the pathway in humans would require careful evaluation of benefits, infection risks, treatment timing and potential unintended immune effects.
Protective Immune Cells Could Reinforce Microglia
Microglia are resident immune cells of the brain and perform important functions including surveillance, debris clearance and inflammatory regulation.
During Alzheimer’s disease, however, microglial function can change considerably.
The researchers’ broader model proposes that circulating monocyte-derived macrophages can act as additional immune reinforcements when resident microglia are unable to adequately respond to accumulating pathology. Previous experimental work has shown that peripheral monocyte-derived cells can participate in restricting amyloid pathology.
The new study provides a possible explanation for why that reinforcement system becomes inadequate.
Rather than the brain simply failing to recruit sufficient cells, Alzheimer’s-related systemic inflammation may be altering the supply of appropriate immune cells before they ever reach the circulation.
Alzheimer’s Disease May Be More Systemic
The research adds to evidence that communication between the brain and peripheral immune system matters in neurodegeneration.
Bone marrow, spleen, circulating immune cells and the interfaces surrounding the central nervous system increasingly appear to participate in processes traditionally viewed primarily through the lens of neurons and brain-resident immune cells.
The Schwartz laboratory at the Weizmann Institute has spent years studying brain-immune communication and the potential contribution of blood-derived immune cells to central nervous system protection and repair.
This systemic perspective does not diminish the importance of amyloid plaques, tau pathology or neurodegeneration.
Instead, it suggests that disease progression may reflect interactions between brain pathology and broader immune dysfunction.
Human Research Is the Critical Next Step
The most important limitation is that the therapeutic findings came from the 5xFAD mouse model.
Mouse models reproduce selected aspects of Alzheimer’s disease but cannot fully recreate the biology, progression and clinical complexity of human dementia.
The detection of altered circulating monocytes in patients strengthens the study’s translational relevance, but researchers will still need to determine whether bone marrow IFN-I dysfunction occurs consistently across larger and more diverse human populations.
Additional work must also establish when these immune changes emerge relative to cognitive symptoms and whether modifying the pathway can safely alter disease progression in people.
Alzheimer’s Immune Dysfunction Expands Treatment Thinking
The study offers a potentially important shift in how scientists think about Alzheimer’s biology.
Instead of focusing exclusively on removing pathological material from the brain, future therapeutic strategies may investigate whether restoring healthier communication between the peripheral immune system and brain can strengthen natural protective mechanisms.
The findings identify bone marrow myelopoiesis and type I interferon signaling as particularly interesting areas for further research.
For now, the discovery remains preclinical rather than a new therapy. But it provides compelling evidence that Alzheimer’s immune dysfunction may involve the body’s blood-cell production system as well as the brain.
If future human studies confirm the mechanism, treating Alzheimer’s could eventually involve not only targeting what happens inside the brain, but also correcting immune dysfunction occurring far beyond it.
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