By Ali Moresco

Growing evidence suggests that Alzheimer’s disease may be shaped not only by age and genetics, but by the immune system’s long-term memory of infection.

In the latest episode of Pathobiome Perspectives, I speak with Alzheimer’s researcher Elizabeth “Betsy” Bradshaw, PhD.

She is Assistant Professor of Neurology at Columbia University Irving Medical Center and Principal Investigator of the Bradshaw Laboratory: Neuroimmunology and Genetics of Alzheimer’s Disease.

Dr. Bradshaw’s research explores how past infections leave lasting imprints on the brain’s immune system, increasing vulnerability to neurodegeneration years, or even decades, later.

Alzheimer’s through an immune lens

Large genome-wide association studies (GWAS) have revealed that many genetic risk factors for Alzheimer’s are linked to immune system pathways, not just neurons. This discovery has shifted research toward understanding how immune cells in the brain respond to infection, inflammation, and environmental stress across a lifetime.

At the center of this work are microglia–AKA the brain’s resident immune cells.

Dr. Bradshaw’s lab uses human-derived microglia-like cells created from blood monocytes to study how pathogens influence immune behavior. By exposing these cells to Alzheimer’s-associated pathogens such as HSV-1 (Herpes Simplex Virus Type 1), her team examines how genetic background and infection history shape immune responses.

Their findings suggest that infections can epigenetically and metabolically reprogram microglia, altering how they respond to aging, stress, and amyloid buildup long after the infection has cleared.

“Microglia remember,” Dr. Bradshaw explains. “Even after the pathogen is gone, they carry its imprint—responding differently decades later when the brain faces new challenges.”

Reframing Alzheimer’s as a neuroimmune disease

Dr. Bradshaw’s work reframes Alzheimer’s as a neuroimmune disease, shaped by the interaction between genetics, infection, and immune memory.

Understanding how immune cells are “trained” by past infections could transform early detection and prevention strategies- making it possible to identify risk and intervene long before symptoms appear.

This research also reinforces a critical message for patients affected by chronic and persistent infections: the immune system’s history matters, and its long-term impact on brain health may be one of the most overlooked factors in neurodegenerative disease.

Binge all the episodes of Pathobiome Perspectives here. 

Pathobiome Perspectives was developed in collaboration with the Pathobiome Research Center at PCOM, led by Founding Director Nikki Schultek, and Director Dr. Brian Balin and the Center for Chronic Disorders of Aging (CCDA). This event was made possible through the joint support of these two PCOM Centers.

Ali Moresco is a tick-borne disease survivor, advocate, speaker and founder of Moresco PR, a healthcare communications firm. She also serves as Executive Board Chair of Project Lyme. You can connect with Ali on Instagram at @AliTMoresco or on YouTube.