First Published Case of Alzheimer's Biomarker Reversal in a Chronic Lyme Disease Patient Using Dapsone Combination Therapy

Peer-reviewed findings published in the Journal of Alzheimer's Disease Reports show a 63% reduction in phosphorylated tau after a nine-week oral protocol

HYDE PARK, N.Y., April 27, 2026 /PRNewswire/ -- Richard I. Horowitz, MD, and the MSIDS Research Foundation published findings today in the Journal of Alzheimer's Disease Reports demonstrating that dapsone combination therapy (DCT), a short-course oral antibiotic regimen, can reverse key biological markers associated with Alzheimer's disease in a patient with chronic Lyme disease. The peer-reviewed case study is the first to show that targeting the persistent, biofilm forms of the Lyme bacterium can normalize phosphorylated tau and improve amyloid beta ratios in the blood, offering a fundamentally new direction for both Alzheimer's prevention and chronic Lyme treatment.

Lyme disease, caused by the spirochetal bacterium Borrelia burgdorferi, is a global epidemic. A 2022 study in BMJ Global Health found that approximately one in seven people globally have been exposed, and the CDC estimates 476,000 Americans are diagnosed each year, with Medicare rates approximately 7x higher. Research has shown that Borrelia burgdorferi can invade the brain as a biofilm infection, co-localizing with amyloid plaques and phosphorylated tau in Alzheimer's autopsy tissue, and prior research has reported a more than tenfold increase in the occurrence of Alzheimer's when spirochetal infections are detected.

"Until now, the standard approach to Alzheimer's treatment has been to name the disease and manage symptoms with pharmaceuticals that do not significantly change its course," said Dr. Richard Horowitz, MD, board-certified internist, Lyme disease researcher, and Medical Director of the Hudson Valley Healing Arts Center, who has treated over 13,000 chronically ill Lyme and tick-borne patients across a 41-year career. "This research shows that when you target the underlying infectious and inflammatory drivers, the brain has a remarkable capacity for recovery. The implications for millions of Americans living with both Lyme disease and cognitive decline could be significant based on this initial research."

Case Study: Dapsone Therapy for Lyme Disease

The patient, a 67-year-old woman with a 15-year history of chronic Lyme disease and co-infections (Babesia, Bartonella, Ehrlichia, and Coxiella burnetii), completed nine weeks of double-dose dapsone combination therapy (DDDCT). The protocol combines dapsone with a tetracycline, rifampin, azithromycin, and methylene blue, along with nutraceutical support including high-dose folic acid.

The patient reported subjective improvements in concentration, memory recall, and joint flexibility. In addition, the study found that:

• P-tau 217 dropped from 0.33 pg/mL (more than double the normal threshold) to 0.12 pg/mL, a 63% reduction, well within normal range.
• Amyloid beta 42/40 ratio improved from 0.185 to 0.216, reducing the estimated future risk of cognitive impairment.
• Rheumatoid factor (a marker of peripheral inflammation) normalized from 20 IU/mL to 12 IU/mL.

This case study and literature review represent Dr. Horowitz's tenth published study on dapsone combination therapy, building on a decade of peer-reviewed research involving more than 365 patients in which cognitive improvement has consistently been the treatment's strongest documented outcome.

Why current Alzheimer's testing guidelines need to change

Current IDSA, AAN, and ACR guidelines do not recommend routine Lyme testing in dementia patients, despite research suggesting a causal link between spirochetal infections and Alzheimer's disease. This case study provides the first direct clinical evidence, using recently validated biomarkers, that treating Borrelia burgdorferi can normalize Alzheimer's markers, supporting the infection-amyloid-tau hypothesis and creating an urgent case for further studies and updated clinical guidelines.

The research applies Dr. Horowitz's 16-point Multiple Systemic Infectious Disease Syndrome (MSIDS) model, a diagnostic and treatment framework that identifies potential underlying sources of inflammation driving chronic illness. Dr. Horowitz has published extensively on the MSIDS model in the context of chronic Lyme disease, as well as Long COVID, and this is the first time this model has been shown to also address potential underlying sources of inflammation affecting Alzheimer's patients. A comprehensive literature review in the study shows that all sixteen factors have been independently published as contributors to Alzheimer's and dementia, providing new avenues for prevention and treatment, giving people hope.

About the MSIDS Research Foundation (MRF)

The MSIDS Research Foundation researches the causes, treatments, and possible cures of tick-borne and other chronic diseases, and works to disseminate scientific knowledge for the benefit of all who suffer from acute and chronic illness.

About Richard I. Horowitz, MD

Dr. Richard Horowitz is a board-certified internist and medical director of the Hudson Valley Healing Arts Center in Hyde Park, New York. Over 41 years of clinical practice, he has treated more than 13,000 patients with Lyme and tick-borne diseases. Dr. Horowitz's newest book, Ending Chronic Illness: A Revolutionary New Program to Reverse Inflammation and Heal Persistent Disease, will be published by Simon & Schuster in October 2026. The book serves as a definitive guide for patients and practitioners alike, providing a paradigm shift to reverse inflammation and heal a broad-range of persistent diseases. Dr. Horowitz is also the author of the New York Times bestseller Why Can't I Get Better? and the national bestseller How Can I Get Better?

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SOURCE MSIDS Research Foundation