For decades, the people arriving at Dr. Richard Horowitz’s Hyde Park practice often came carrying two things: a long list of symptoms and a longer history of trying to explain them. Fatigue, pain, disrupted sleep, and difficulty thinking had sent them from one specialist to another. Some had already been treated for Lyme disease. They were still sick, and the distance between having a diagnosis and getting their lives back could be enormous.
Horowitz built his career inside that distance. A board-certified internist and the longtime medical director of the Hudson Valley Healing Arts Center, he estimates that he has treated 13,000 chronically ill patients during his medical career. Their experiences gradually changed the questions he asked, the conditions he investigated, and his understanding of what medicine could miss when it divided a complicated illness into separate appointments.
“I’ve learned that many of these patients don’t have one underlying source of inflammation,” he says. “They have many.”
That conviction animates his new book, Ending Chronic Illness: A Revolutionary New Program to Reverse Inflammation and Heal Persistent Disease (Avid Reader Press). It also shapes his next chapter. After winding down his practice and keeping a few patients through this year, Horowitz officially closed the office several months ago. He continues consulting with physicians and wants to concentrate on research that could test his approach on a larger scale.
“I’m now going to move into the research space, where I can serve the millions,” he says.
A Practice Changed by Its Patients
In the book, Horowitz recalls finishing his internal medicine residency at Mount Sinai in 1987. Horowitz moved to the Hudson Valley, envisioning a life as a country doctor. He would know his patients, treat familiar problems such as hypertension and diabetes, and enjoy the region’s hiking trails. Practicing in a Lyme hot spot redirected that ambition. Patients arrived with combinations of symptoms that persisted despite treatment, and referrals to specialists did not always produce answers.
One early case helped expand his thinking beyond Lyme itself. A woman who used a wheelchair had drenching sweats, a symptom that suggested a malaria-like infection. In Horowitz’s account, testing identified Babesia, another tick-borne pathogen. After treatment directed at that infection, she regained strength and eventually walked. The lesson he took from the case was that treating one infection could leave another untreated.
Over time, his investigations expanded to include sleep problems, nutritional deficiencies, hormonal abnormalities, environmental exposures, and other potential contributors to persistent symptoms. The practice became an integrative medical center, combining conventional treatment with complementary approaches. His work also took him into physician education and public policy, including service on federal and New York State tick-borne disease working groups.
His 2013 book, Why Can’t I Get Better?, followed by How Can I Get Better? in 2017, brought that approach to readers struggling with resistant Lyme and chronic disease. The new book widens the scope considerably, examining conditions ranging from long Covid and digestive disorders to cardiovascular disease and Alzheimer’s. Across those chapters, Horowitz returns to the same organizing idea: identify the overlapping factors that may be sustaining inflammation.
Mapping the Overlap
Inflammation is the organizing principle of Horowitz’s new book. He sees it as a thread connecting illnesses that medicine often treats separately: persistent Lyme symptoms, long Covid, digestive disorders, and neurodegenerative disease. His central question: What keeps that inflammatory response going in a particular patient—and whether identifying and treating those contributors can improve their health.
His framework, MSIDS—multiple systemic infectious disease syndrome—is a map of those possible contributors and their effects. An infection might be one source; disrupted sleep, nutritional deficiencies, or environmental exposures might be others. In Horowitz’s model, several can operate simultaneously, helping explain why treating a single problem may leave a patient feeling profoundly unwell. “I’ve learned that many of these patients don’t have one underlying source of inflammation,” he says. “They have many.”
The breadth of that argument is also what requires testing. Evidence linking inflammation to different diseases does not establish that those diseases share the same causes or will respond to the same treatment. Horowitz’s ambition is to turn those connections into a practical method: identify what may be sustaining inflammation, address it, and assess whether both symptoms and laboratory findings improve.
The book organizes the framework into 16 points. Six are proposed drivers of inflammation: infections, environmental toxins, microbiome abnormalities, increased intestinal permeability and food sensitivities, vitamin and mineral deficiencies, and sleep disorders. Ten describe possible downstream effects, including hormonal and immune dysregulation, neurological problems, pain, impaired cellular energy production, and deconditioning. Horowitz acknowledges that some relationships can run in both directions, with consequences of illness becoming contributors themselves.
This map guides his investigations. Instead of assuming a diagnosis accounts for every complaint, he works backward from symptoms to possible explanations. Physicians call that process a differential diagnosis. He cites nerve pain as an example: Infections are among the possibilities he considers, along with nutritional deficiencies, thyroid problems, toxic exposures, and nerve compression. “For every symptom, there is a way to go backward and figure out where the symptom is coming from,” he says.
The opening patient story in the book demonstrates both the breadth and the demands of that approach. Gerry, a 48-year-old struggling after Covid, comes to Horowitz with fatigue, headaches, brain fog, pain, and insomnia. Horowitz describes identifying numerous additional problems, including hormonal abnormalities, nutritional deficiencies, and autonomic nervous system dysfunction. According to the book, addressing them took nearly a year before Gerry returned to normal health.
Such accounts give the framework its narrative force. They also pose a research question: When several problems are treated together, how can investigators determine which findings mattered, which interventions helped, and whether another patient would benefit similarly?
What the Evidence Can Show
Horowitz is emphatic about the improvements he has witnessed. He is also explicit about the next level of evidence needed to persuade the wider medical community: randomized, multicenter, placebo-controlled trials.
Much of the evidence he cites for his Lyme treatment approach comes from retrospective studies, which examine patients’ experiences after treatment. These can reveal patterns and generate hypotheses, but they do not provide the same protection against bias as studies that randomly assign comparable patients to treatment and control groups. Improvement following treatment does not, by itself, establish what caused the improvement.
This difference is especially important in treating Lyme. The CDC recognizes that some patients experience prolonged fatigue, pain, and cognitive difficulties after antibiotic treatment. It says the cause of these persistent symptoms remains unknown and that controlled studies have generally found extended antibiotic treatment no better than placebo for curing prolonged symptoms. That evidence forms an important backdrop to Horowitz’s argument for further testing of his particular protocols.
His current interest in Alzheimer’s raises similarly consequential questions. In an April 2026 paper in the Journal of Alzheimer’s Disease Reports, Horowitz described a 67-year-old woman with longstanding Lyme-related symptoms whose elevated blood level of phosphorylated tau 217, a biomarker associated with Alzheimer’s pathology, returned to the laboratory’s normal range after dapsone combination therapy. The regimen pairs dapsone—an antibiotic traditionally used to treat leprosy—with other antibiotics to target what Horowitz believes are persistent forms of Lyme bacteria. The paper also reported reduced pain and improvements in concentration and recall reported by the patient.
The report concerns one patient. It does not establish that Lyme causes Alzheimer’s, that the treatment reverses dementia, or that lowering the marker prevents future cognitive decline. For Horowitz, however, the findings justify investigating whether infections and other factors on his MSIDS map contribute to disease in a broader population.
During the interview, he described plans to discuss a pilot study with physician and Alzheimer’s author Dale Bredesen. The proposed investigation would look at Lyme and other MSIDS factors in patients with Alzheimer’s, as well as Alzheimer’s-related biomarkers in Lyme patients. Those plans represent a research direction, not completed results.
Giving Patients Better Questions
Although Ending Chronic Illness addresses patients directly, much of it contains material for clinicians: testing strategies, laboratory interpretation, treatment protocols, and extensive references. Its practical aim is to give readers a framework for discussing persistent symptoms with their healthcare providers.
Horowitz suggests beginning with the symptom questionnaire included in the book and bringing the results to a physician. A questionnaire can help organize a history and guide discussion; it cannot establish a diagnosis by itself. He also emphasizes that many tests can be obtained through ordinary laboratories, while acknowledging that he uses specialized testing in some circumstances.
His enthusiasm extends to wider use of Alzheimer’s-related blood biomarkers. Here, too, his recommendations reach beyond current professional guidance. The Alzheimer’s Association’s 2025 guideline addresses their use in people with objective cognitive impairment receiving specialized care, following a comprehensive clinical evaluation. It does not establish them as routine screening tests for everyone concerned about inflammation.
For readers, the book’s most useful starting point may be its insistence on a detailed conversation: Which symptoms remain unexplained? What possibilities have been investigated? What would a test result change about treatment? How will improvement be assessed?
Horowitz says he has seen inflammatory markers decline alongside recovery, but he keeps returning to the patient’s experience. “Remember, the most important thing is the patient and how the patient is feeling,” he says. A laboratory number is part of the picture; being able to think clearly, work, sleep, and participate in daily life is the outcome patients are seeking.
With the office closed, he is making himself available to physicians seeking help with complex cases and anticipates further doctor training. The shift carries the same ambition that drove the practice: make persistent illness more understandable and give patients more effective options. His next task is to determine, through stronger studies, how much of what he learned in one Hudson Valley office can reliably help people far beyond it.
This article appears in November 2026.
