Michael A. Diefenbach, PhD

Professor, Merinoff Center for Patient-Oriented Research, The Feinstein Institure for Medical Research

Director, Behavioral Research, Department of Medicine & Urology

Professor, Hofstra Northwell School of Medicine

Phone: (516) 321-8001
Email: mdiefenbach@northwell.edu

About the Investigator

Dr. Diefenbach is a behavioral scientist with a degree in Health/Social Psychology whose research focuses on how patients make treatment decisions under distressing and uncertain medical conditions. He has investigated basic psychological mechanisms of decision making, focusing on individual cognitive and affective factors and their influences on information processing, decisional satisfaction, regret and quality of life. Guided by a self-regulation theoretical framework, Dr. Diefenbach translates and applies basic psychological phenomena into applied patient focused interventions with the goal of enhancing enhancing patient quality of life through improved decision making and symptom control.

Dr. Diefenbach’s research has been continuously federally funded for over 20 years and has involved a variety of patient populations, including prostate, bladder, and breast cancer patients. In an effort to enhance patient decision making he has developed in-person as well as web-based programs. His Prostate-Interactive Education System (PIES) was one of the first web-based comprehensive and interactive prostate cancer information resources for newly diagnosed prostate cancer patients. In addition, he guided the development of three additional programs: Healing Choices for Prostate Cancer and Healing Choices for Breast Cancer, as well as a web-based resource for prostate cancer survivors (PROGRESS).

More recently, Dr. Diefenbach developed applications for the smart phone to support a slow-breathing exercise to control vasomotor symptoms experienced by men on androgen deprivation therapy (2Breathe) and a cancer screening information tool (HealthOwl). He is currently developing a decision making application for a low-health literate prostate cancer population (Healium).

Before joining Northwell Health, Dr. Diefenbach was Associate Professor of Urology and Oncological Sciences at the Icahn School of Medicine at Mount Sinai, New York. Dr. Diefenbach serves on the editorial board of Annals of Behavioral Medicine and Cancer Epidemiology, Biomarkers, and Prevention. He is also a Senior Editor of Translational Behavioral Medicine. He is a frequent reviewer for the Department of Defense, the Veteran’s Administration and the National Institutes of Health, where he served as a permanent member of the Behavioral Medicine and Intervention study section (BMIO). He was elected to Fellow status of the Society of Behavioral Medicine and the Academy of Behavioral Medicine. He has been serving as secretary/treasurer of the Society of Behavioral Medicine since 2012.

Research Focus

Dr. Diefenbach’s program of research has several foci: on the basic psychologicial level he is interested in the cognitive and affective factors as they relate to health behaviors and decision making. On an applied level, he is translating these basic findings into patient-centered interventions, with the goal to improve patient adjustment to disease and treatment and quality of life. Within this general framework, Dr. Diefenbach is conducting studies to examine and improve risk communication between patients and physicians, enhance decision making for a variety of at-risk populations, explore new ways to educate patients through innovative programs on multiple electronic platforms, and enhance symptom control during treatment. His research research follows strict methodological standards using both quantitative and qualitative methods, is rigorously evidence based and transparent.


University of Mainz, Germany
Degree: BS
Field of Study: Psychology

University of Wisconsin, Madison
Degree: MS
Field of Study: Social/Health Psychology

Rutgers, The State University of New Jersey
Degree: PhD
Field of Study: Social/Health Psychology

Rutgers, The State University of New Jersey, The Institute for Health
Degree: Post-doctorial fellow
Field of Study: Health Care Policy and Aging

Fox Chase Cancer Center, The Division of Population Science
Degree: Advanced cancer training fellow
Field of Study: Psychosocial and Behavioral Medicine

Honors and Awards

2012-Present Treasurer/Secretary, Society of Behavioral Medicine
2012 Elected to fellow status for the Society of Behavioral Medicine
2010 C. Tracey Orleans Distinguished Service Award, Society of Behavioral Medicine
2009, 2010 Program Chair for the annual conference and scientific sessions Society of
Behavioral Medicine
1992 Dissertation Research Award from the American Psychological Association for
outstanding research proposal
1989, 1991 Travel Awards from the American Psychological Association to attend and
present research at the annual meetings
1986, 1987 Fulbright Fellowship to study Health Psychology at the University of
Wisconsin, Madison, WI

  1. Wu, L. M., Tanenbaum, M. L., Dijkers, M. P., Amidi, A., Hall, S. J., Penedo, F. J., & Diefenbach, M.A. (2016). “Cognitive and neurobehavioral symptoms in patients with non-metastatic prostate cancer treated with androgen deprivation therapy or observation: A mixed methods study.” Social Science & Medicine, 156, 80-89. doi:10.1016/j.socscimed.2016.03.016.
  2. Badr H, Lipnick D, Diefenbach M.A., Posner M, Kotz T, Miles B, Genden E. “Development and usability testing of a web-based self-management intervention for oral cancer survivors and their family caregivers.” Eur J Cancer Care (Engl). 2015 Oct 27. doi: 10.1111/ecc.12396. PMID: 26507369.
  3. Shen MJ, Nelson CJ, Peters E, Slovin SF, Hall SJ, Hall M, Herrera PC, Leventhal EA, Leventhal H, Diefenbach M.A. “Decision-making Processes among Prostate Cancer Survivors with Rising PSA Levels: Results from a Qualitative Analysis. Med Decis Making.” 2015 May; 35(4):477-86. doi: 10.1177/0272989X14558424. Epub 2014 Nov 10. PMID: 25385751; PMCID: PMC4424110.
  4. Badr H, Carmack CL, Diefenbach M.A. “Psychosocial interventions for patients and caregivers in the age of new communication technologies: opportunities and challenges in cancer care.” J Health Commun. 2015;20(3):328-42. doi: 10.1080/10810730.2014.965369. Epub 2015 Jan 28. Review. PMID: 25629218; PMCID: PMC4361271.
  5. Phillips, L. A., Diefenbach, M.A., Abrams, J., & Horowitz, C. R. (2015). “Stroke and TIA survivors’ cognitive beliefs and affective responses regarding treatment and future stroke risk differentially predict medication adherence and categorized stroke risk.” Psychology & Health, 30(2), 218-232. doi:10.1080/08870446.2014.964237.
  6. Wu LM, Austin J, Valdimarsdottir H, Isola L, Rowley SD, Diefenbach M.A., Cammarata M, Redd WH, Rini C. (2014) “Cross-sectional study of patient-reported neurobehavioral problems following hematopoietic stem cell transplant and health-related quality of life.” Psychooncology, 23(12), 1406-1414. doi:10.1002/pon.3554.

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