Researchers at the MSIDS Research Foundation and Hudson Valley Healing Arts Center in Hyde Park, New York, report that a nine-week course of double-dose dapsone combination therapy normalized phosphorylated tau and amyloid beta blood biomarkers in a single chronic Lyme disease patient with Alzheimer's-associated pathology, according to a study published April 27, 2026 in the Journal of Alzheimer's Disease Reports.
The case report describes a 67-year-old woman with a 15-year history of chronic Lyme disease and co-infections including Babesia, Bartonella, Ehrlichia, and Coxiella burnetii. Pre-treatment blood testing showed abnormal levels of P-tau 217 and an abnormal amyloid beta 42/40 ratio, both validated surrogate markers for Alzheimer's-associated neurodegeneration and amyloid plaque burden. Following a nine-week oral regimen combining dapsone, tetracycline, rifampin, azithromycin, and methylene blue, alongside high-dose folic acid and nutraceuticals, both biomarkers returned to normal ranges. Rheumatoid factor, used as an index of systemic inflammation, also declined. The authors, led by Richard I. Horowitz, MD, describe this as the first published case of Alzheimer's biomarker normalization in a patient with chronic Lyme disease.
The study frames its findings within the infection-amyloid-tau hypothesis, which posits that persistent Borrelia burgdorferi infection drives neuroinflammation that in turn promotes amyloid deposition and tau hyperphosphorylation. Prior autopsy-based research has identified co-localization of Borrelia biofilm forms with amyloid plaques and phosphorylated tau in brain tissue, though a causal relationship has not been established in controlled human studies. The MSIDS framework used by Horowitz positions Alzheimer's in some patients as a downstream consequence of untreated or undertreated tick-borne infection rather than a primary idiopathic neurodegenerative process.
The multi-drug protocol was designed to address the biofilm-phase persistence of Borrelia burgdorferi, which is considered resistant to standard single-agent antibiotic regimens. Dapsone, administered at double dose, was selected for its anti-inflammatory properties and activity against biofilm-phase bacteria. Rifampin was included for intracellular penetration, azithromycin for coverage of persistent bacterial forms, and methylene blue for mitochondrial support and potential anti-tau aggregation activity. High-dose folic acid was co-administered to reduce the risk of dapsone-associated hemolytic anemia.
The report is a single-patient case study with no control group, no randomization, and no blinding. Within-patient pre- and post-treatment biomarker comparisons constitute the entirety of the evidence base. No formal statistical analysis is applicable at N=1, and spontaneous biomarker fluctuation cannot be excluded. The study does not report cognitive outcome measures, meaning biomarker normalization has not been linked to functional or clinical improvement in this patient. The paper was authored by the treating physician and published under the auspices of his own foundation, which carries conflict-of-interest considerations standard to investigator-initiated case reports.