About

Joseph H Friedman is a Professor of Neurology with extensive expertise in movement disorders, particularly Parkinson's disease, Huntington's disease, Machado-Joseph disease, episodic ataxia type 2, and drug-induced movement disorders. He obtained his bachelor's degree in mathematics from the University of Chicago, a master's in math from Washington University, and an MD from Columbia University College of Physicians and Surgeons. His training includes a neurology residency at the Neurological Institute of New York, Columbia-Presbyterian Medical Center. Since moving to Rhode Island in 1982, he has dedicated his career to clinical research and patient care in neurology. Friedman has served on the executive committee of the Parkinson Study Group, editorial boards of prominent neurology journals, and was editor-in-chief of the Rhode Island Medical Journal for 20 years. His research interests focus on behavioral aspects of Parkinson's disease, including drug-induced psychosis and fatigue, and he evaluates the effects of various pharmacological treatments. He has been involved in multiple NIH-funded studies exploring genetics, neuroprotection, and cognitive interventions in Parkinson's and Huntington's diseases. Friedman has published over 200 peer-reviewed articles and is a fellow of the American Academy of Neurology and the American Neurological Association.

Research topics

• Medicine
• Sociology
• Demography
• Emergency medicine
• Medical emergency
• Internal medicine
• Psychiatry
• Environmental health
• Political Science
• Computer Security
• Anesthesia
• Criminology
• Law
• Virology
• Pediatrics
• Psychology
• Geography
• Biology
• Social psychology
• Nursing

Selected publications

• US overdose mortality saw first drop below the Jalal-Burke exponential growth curve in 2024

  International Journal of Drug Policy · 2026-05-09

  article1st authorCorresponding
  PublisherDOI

• Mental Health Care for Refugees, Immigrants, and Migrants in the United States

  Psychiatric Services · 2026-05-12

  article

  Diverse refugee, immigrant, and migrant (RIM) populations in the United States face complex mental health needs that are shaped by migration experiences, cultural transitions, and structural barriers to accessing care. Although RIM populations have different legal statuses, cultural backgrounds, and lengths of U.S. residence, many encounter common stressors related to uncertain immigration policies, economic instability, and limited access to culturally responsive services. Recent federal actions-including suspension of the U.S. Refugee Admissions Program and revocation of "protected areas" policies-have intensified fears and mental health vulnerabilities among these populations. Using a multilevel, biopsychosocial approach, the authors aimed to provide clinical guidance on the biological, structural, sociocultural, and health care system factors that affect mental health care delivery for RIM populations. This article provides evidence-based clinical guidance and actionable recommendations that allow clinicians to selectively apply interventions (e.g., trauma-informed practices, low-barrier care models, medical-legal partnerships, and culturally responsive approaches that respect alternative healing frameworks) on the basis of individual patient circumstances. Key recommendations pertain to working with professional interpreters, navigating diagnostic ambiguity, and interfacing with immigration enforcement.

  PublisherDOI

• Charting the Decline of the Fourth Wave: US Overdose Deaths by Race, Ethnicity, and Substance Involvement

  medRxiv · 2026-01-30 · 1 citations

  articleOpen access1st authorCorresponding

  Aims: To characterize decreases in overdose death rates in the United States between 2023 and 2024 by race/ethnicity, and substance involvement. Design: Population-based study of national death records accessed via the Centers for Disease Control and Prevention (CDC) Wide-ranging ONline Data for Epidemiologic Research (WONDER) platform using an underlying cause of death approach. Setting: United States (US). Participants/cases: All individuals who died from drug overdose between January 1999 and December 2024. Measurements: Annual overdose deaths per 100,000 population. Year of occurrence of overdose death; substance involvement; race/ethnicity of decedents. Findings: After many years of increases, the US overdose death rate dropped 24.4% between 2023 and 2024. Decreases reflected declining illicit fentanyl-involved deaths (with and without stimulant involvement). The fourth wave of the US overdose crisis-defined by deaths involving fentanyl together with stimulants-declined for the first time in 2024. Despite overall decreases, deaths involving stimulants without fentanyl, and xylazine, continued to represent a growing fraction of overdose fatalities. Non-Hispanic Black and African Americans had the largest decrease in death rates in 2023-2024-falling 29.3%, but remained elevated at 36.0 per 100,000, 1.51 times higher than the national average of 23.7 per 100,000. Non-Hispanic American Indian and Alaska Native individuals had the highest overdose death rates rate in 2024, at 50.8 per 100,000, representing 2.15 times the national average rate, and experienced a below-average relative decrease of 20.1%. Conclusions: All four previously defined waves of the US overdose crisis are in decline, as deaths involving illicit fentanyl, with and without stimulants, are dropping sharply. Concurrently, the fraction of overdose deaths involving stimulants without fentanyl and those involving xylazine, continued to increase. While racial disparities in drug overdose death rates narrowed slightly during this period, significant gaps remain, with the highest rates among American Indian, Alaska Native, and Black individuals.

  PublisherOA PDFDOI

• Assessing the real-world performance of xylazine test strips for community-based drug checking in Los Angeles

  Harm Reduction Journal · 2026-02-08

  articleOpen access

  BACKGROUND: The veterinary sedative xylazine is increasingly found in illicit fentanyl and has been associated with numerous health harms. Xylazine test strips (XTS) are an emerging technology that can theoretically assist consumers in avoiding xylazine, but they require real-world validation. We leverage community-based drug checking program data to compare real-world XTS performance to 'gold standard' methods. METHODS: Samples were initially assessed by dissolving 1 mg of drug product in 1 mL water and dipping an XTS ("first generation" Wisebatch™) in the sample. Subsequently, confirmatory testing was performed by sending samples to the National Institute of Standards and Technology for qualitative analysis using direct analysis in real-time mass spectrometry (DART-MS). A subset was analyzed quantitatively with liquid chromatography gas spectrometry (LC-MS) to quantify xylazine, fentanyl, and other compounds. RESULTS: A total of n = 1570 drug samples were analyzed between June 2023 and May 2025, and a total of n = 801 XTS were used. N = 715 comparisons between xylazine test strips and mass spectrometry results could be made, including n = 333 among samples that tested positive for fentanyl. Of these, n = 63 samples were confirmed to contain xylazine by mass spectrometry, of which the majority contained low concentrations (average concentration 2.3%; 78% of samples contained less than < 1% xylazine by weight). Of the 63, n = 34 were correctly identified as positive by XTS, yielding sensitivity of 54.0 %. Of n = 270 xylazine negative samples, n = 235 were correctly categorized (specificity = 87.0%). Most false positives occurred with lidocaine present. CONCLUSIONS: In our sample, with a large percentage of low concentration xylazine samples, "first generation" Wisebatch XTS had a relatively low sensitivity, but higher specificity. This highlights the value of confirmatory testing and the complicated and often confusing nature of point-of-care test strips for novel substance detection. Lot testing and validation studies are needed to improve quality control in this area.

  PublisherDOI

• Substance Use Disorder and Harm Reduction Curriculum in United States and Canadian Undergraduate Medical Education: An Online Survey

  Substance Use &amp Addiction Journal · 2025-02-06

  articleOpen access

  BACKGROUND: Substance use disorders (SUD) are a significant public health challenge, necessitating that clinicians are trained in SUD treatment and harm reduction (HR) strategies. Despite this, no studies have assessed the extent of SUD and HR training across all medical schools. This study assesses the current state of SUD and HR curriculum among medical students in the United States and Canada. METHODS: From May to July 2023, we conducted an anonymous online survey via email invitation to student affairs' offices of all 220 accredited US and Canadian medical schools. The survey assessed the curricula students were exposed to related to SUD treatment, HR, and stigmatizing attitudes. RESULTS: A sample of 568 students from 52 medical schools (23.6% of all US and Canadian medical schools) completed the survey. Participants reported that in their medical school they were taught about: recognition of an opioid overdose (80.0%), identifying and treating opioid withdrawal (68.2%), principles and practices of HR (60.6%), administering naloxone (56.6%), the importance of syringe service programs (51.8%), prescribing methadone and/or buprenorphine (29.5%), and counseling patients on safe injection practices (11.4%). In addition, participants reported that they were taught: how to identify drug-seeking behavior (36.4%), that people who use heroin are "drug abusers" (24.4%), to withhold opioid pain medication from patients who are known or suspected to use drugs (15.9%), and that medication for opioid use disorder is another form of addiction (12.6%). DISCUSSION: We found large curricular gaps related to the administration of medications for opioid use disorder and treating opioid overdose and withdrawal, as well as a significant prevalence of stigmatizing attitudes. Renewed efforts are needed to implement comprehensive and destigmatizing SUD curricula. The study is limited by response bias and is expected to overestimate the extent of HR related curriculum, indicating the true gap is likely higher than reported.

  PublisherDOI

• Crystal Clear: Purity of consumer-level methamphetamine samples and methamphetamine-adulteration of other drugs in Los Angeles, 2023-2025

  medRxiv · 2025-03-19 · 1 citations

  preprintOpen access

  Introduction: The United States (US) has seen a rise in methamphetamine use disorders and methamphetamine-involved deaths. The US Department of Justice and Drug Enforcement Agency reports that seized wholesale methamphetamine is almost uniformly high purity. However, there is limited information on the concentration of methamphetamine at the consumer level. We leverage data from a community-based drug checking program in Los Angeles to investigate (1) the makeup of the retail illicit methamphetamine market and (2) the extent to which methamphetamine plays a role as an adulterant in other drugs. Methods: Anonymous participants accessing a community-based drug checking program voluntarily provided samples of illicit drug products and completed brief interviews at four sites in Los Angeles County, California, from February 2023 to January 2026. Samples underwent laboratory-based qualitative testing via direct analysis in real-time mass spectrometry (DART-MS) and quantitative liquid-chromatography mass spectrometry (LC/MS). We quantitated the presence and concentration of methamphetamine as well as all other identified substances among 1) samples expected only to be methamphetamine and 2) samples expected to be another substance (e.g., fentanyl, heroin) where methamphetamine was found as an adulterant/contaminant. Results: Of N=2193 total samples, n=652 (29.7%) were methamphetamine-positive on DART-MS. Among methamphetamine-positive samples, the drug was an expected component in two thirds of samples and unexpected in one third. In samples expected to contain methamphetamine, the mean purity was 78.2% (SD 24.0%; range <1% to ≈100%). As an unexpected component, the mean methamphetamine purity was 17.8% (SD 32.3%), and was mostly commonly found in samples expected to be fentanyl, heroin, MDMA, other amphetamines (e.g., counterfeit Adderall), and 2C-B. Conclusions: Consumers in Los Angeles seeking methamphetamine appear to frequently obtain high-purity samples that are rarely adulterated with other substances, although we observed a wide variation in concentration between samples. In contrast, drugs purchased without the expectation of containing methamphetamine had substantively high prevalence of methamphetamine adulteration/contamination. Both intentional and unwitting consumers may be vulnerable to the health risks of potent and variable methamphetamine, including psychiatric, cardiovascular, and other illnesses. Future research should expand methamphetamine surveillance techniques and investigate how variability in illicit markets may impact health outcomes. Highlights: Samples expected to contain methamphetamine had a mean purity of 72% (SD 24%).For 90% of samples expected to be meth, no other active compounds were detected.Meth was a substantial adulterant in other drugs, e.g. opioids (mean purity 17%).

  PublisherOA PDFDOI

• Assessing the Real-World Performance of Xylazine Test Strips for Community-Based Drug Checking in Los Angeles

  medRxiv · 2025-06-30

  preprintOpen access

  Abstract Background The veterinary sedative xylazine is increasingly found in illicit fentanyl and has been associated with numerous health harms. Xylazine test strips (XTS) are an emerging technology that can theoretically assist consumers in avoiding xylazine, but they require real-world validation. We leverage community-based drug checking program data to compare real-world XTS performance to ‘gold standard’ methods. Methods Samples were initially assessed by dissolving 1mg of drug product in 1mL water and dipping an XTS (“first generation” Wisebatch™) in the sample. Subsequently, confirmatory testing was performed by sending samples to the National Institute of Standards and Technology for qualitative analysis using direct analysis in real-time mass spectrometry (DART-MS). A subset was analyzed quantitatively with liquid chromatography gas spectrometry (LC-MS) to quantify xylazine, fentanyl, and other compounds. Results A total of n=1,570 drug samples were analyzed between June 2023 and May 2025, and a total of n=801 XTS were used. N=715 comparisons between xylazine test strips and mass spectrometry results could be made, including n=333 among samples that tested positive for fentanyl. Of these, n=63 samples were confirmed to contain xylazine by mass spectrometry, of which the majority contained low concentrations (average concentration 2.3%; 78% of samples contained less than &lt;1% xylazine by weight). Of the 63, n=34 were correctly identified as positive by XTS, yielding sensitivity of 54.0%. Of n=270 xylazine negative samples, n=235 were correctly categorized (specificity=87.0%). Most false positives occurred with lidocaine present. Conclusions In our sample, with a large percentage of low concentration xylazine samples, “first generation” Wisebatch XTS had a relatively low sensitivity, but higher specificity. This highlights the value of confirmatory testing and the complicated and often confusing nature of point-of-care test strips for novel substance detection. Lot testing and validation studies are needed to improve quality control in this area.

  PublisherOA PDFDOI

• High variation in purity of consumer-level illicit fentanyl samples in Los Angeles, September 2023–April 2025

  International Journal of Drug Policy · 2025-08-30 · 6 citations

  articleOpen accessSenior author

  BACKGROUND: The illicit manufacture of fentanyl results in product of unknown purity, contributing to overdose risk. However, data on the purity of illicitly manufactured fentanyl (IMF) in the United States typically comes from law enforcement sources and almost no information relevant to retail-level product is made available. We aim to quantify IMF purity among samples from a community-based drug checking program operating at four geographic sites in Los Angeles, California. METHODS: Drug samples (n = 1763) were obtained from participants who also answered an anonymous survey about sample characteristics. Qualitative and quantitative analysis were conducted leveraging directly observed mass spectrometry (DART-MS) and liquid chromatography mass spectrometry (LC/MS) respectively. LC/MS quantified a panel of compounds including fentanyl and fluorofentanyl. Composite IMF purity was estimated by adding the percent mass of fentanyl and fluorofentanyl. RESULTS: A total of 353 samples had either fentanyl, fluorofentanyl, or both quantified between September 2023 and April 2025. Median IMF purity was 5.8 %, mean 10.0 %, SD 11.1 %, range 0.1-64.9 %. Samples expected to be fentanyl (n = 308) had higher median purity (7.0 %) compared to those expected to be heroin (n = 24, median purity 1.4 %) or other drugs (p < 0.001). Powder samples (n = 318) had higher median concentration (6.9 %) compared to pills (n = 11, 0.7 %) or tar (n = 22, 1.4 %) [p < 0.001]. Of expected-fentanyl samples, 42.5 % (n = 131) had an IMF purity of <5 %, while 17.5 % (n = 54) had purity over 20 %. CONCLUSIONS: We found high variation in IMF purity among samples sold as fentanyl, even among samples obtained on the same day, in the same location. This volatility likely plays a role in high overdose risk, even among people with opioid tolerance, in the fentanyl era. Further research is needed to compare these findings to other locations across the United States.

  PublisherDOI

• Estimating the Daily Milligrams of Morphine Equivalent of Illicit Fentanyl Use in Los Angeles: Clinical and Epidemiological Implications

  medRxiv · 2025-10-08 · 1 citations

  preprintOpen access

  Introduction: The market shift from heroin to illicitly-manufactured-fentanyl in North America led to surging opioid mortality. However, limited information exists about the doses of illicit fentanyl regularly consumed. We examined purity of fentanyl samples and estimate the typical daily oral milligrams of morphine equivalent (MME). Methods: Leveraging community-based drug checking data from Los Angeles, we ascertained the purity of 509 samples of fentanyl collected between September 2023 and January 2026 using liquid chromatography mass spectrometry. We assessed typical consumption quantity and routes of administration among 47 respondents who reported regularly using fentanyl. We estimate bioavailability and MME conversion factors from literature. To estimate daily MME, incorporating all parameter uncertainty, we used a bootstrapping approach with 1,000,000 draws, with sensitivity analyses to assess the impact of factors including the correlation between purity and quantity. Results: Among participants, the mean daily consumption of fentanyl was 1.07 grams (95% prediction interval: 0.03g-4.00g). Illicit fentanyl products had a mean fentanyl purity of 12.47% (0.23%-38.80%), and the mean estimated bioavailability based on routes of administration was 50.82% (30.64%-76.75%). The mean estimated IV fentanyl to PO morphine MME conversion factor was 1 to 183.15 (71.85 - 294.21). The mean estimated daily consumption in our sample was 8,887.55 MME (156.56 MME-41,761.3 MME). Conclusions: Under all plausible estimation scenarios, individuals consuming illicit fentanyl in Los Angeles on average use a quantity of MME several orders of magnitude higher than clinical guidelines or typical methadone doses. This likely contributes to high overdose mortality, high opioid tolerance, and more difficult methadone and buprenorphine induction.

  PublisherOA PDFDOI

• The Detection of Xylazine in Tijuana, Mexico: Triangulating Drug Checking and Clinical Urine Testing Data

  Journal of Addiction Medicine · 2025-03-20 · 5 citations

  article1st authorCorresponding

  INTRODUCTION: Xylazine is a veterinary anesthetic increasingly present alongside illicit fentanyl in the United States and Canada, presenting novel health risks. Although xylazine remains less common in the Western US, Mexican border cities serve as key trafficking hubs and may have a higher prevalence of novel substances, but surveillance there has been limited. METHODS: We examined deidentified records from the Prevencasa free clinic in Tijuana, describing urine and paraphernalia testing from patients reporting using illicit opioids within the past 24 hours. Xylazine (Wisebatch and Safelife brands), fentanyl, opiate, methamphetamine, amphetamine, benzodiazepine, and nitazene test strips were used to test urine and paraphernalia samples. Paraphernalia samples were also analyzed with mass spectrometry. RESULTS: Of n=23 participants providing urine and paraphernalia samples concurrently, 100%, 91.3%, and 69.6% reported using China White/fentanyl, methamphetamine, and tar heroin, respectively. The mean age was 41.7 years, 95.7% were male, 65.2% were unhoused, and 30.4% had skin wounds currently. Xylazine positivity in urine for the 2 strip types used was 82.6% and 65.2%. For paraphernalia testing, the xylazine positivity was 65.2% and 47.8%. Confirmatory testing of paraphernalia samples by mass spectrometry indicated a 52.2% xylazine positivity, as well as fentanyl (73.9%), fluorofentanyl (30.4%), tramadol (30.4%), and lidocaine (30.4%). Mass spectrometry suggested lidocaine triggered n=3 and n=0 false positives among the xylazine test strip types. DISCUSSION: Xylazine is present on the US-Mexico border, requiring public health intervention. High lidocaine positivity complicates the clinical detection of xylazine via testing strips. Routine urine testing for xylazine in clinical scenarios is likely feasible, yet confirmatory urine studies are needed.

  PublisherDOI

Frequent coauthors

• Christopher J L Murray

  University of Washington

  61 shared

• Emmanuela Gakidou

  59 shared

• Dan J. Stein

  South African Medical Research Council

  53 shared

• Nancy Fullman

  50 shared

• In‐Hwan Oh

  University of Washington

  47 shared

• Ai Koyanagi

  Instituto de Salud Carlos III

  47 shared

• Chuanhua Yu

  45 shared

• Rachel L Updike

  45 shared

Education

• B.S., Mathematics

  University of Chicago

• M.S., Math

  Washington University

• M.D.

  Columbia University College of Physicians and Surgeons

Awards & honors

• Fellowship in the American Academy of Neurology
• Fellowship in the American Neurological Association