As a resident of Mather Hospital, you will have the distinction of working with, and being mentored by, a remarkable group of board-certified physicians. Our faculty includes nationally recognized clinicians and researchers, with vast levels of experience teaching and guiding students in their journey to becoming a licensed physician. All of our faculty are board certified, some in in multiple specialties, bringing a well-rounded knowledge to each rotation they supervise. The physicians listed below are considered the core faculty of the residency program. 

Jenna Taglienti, MD serves as Program Director for the Psychiatry Residency Program and Medical Director of the Mental Health Clinic.  She is an Assistant Professor at Zucker/Hofstra School of Medicine.  Board certified in Adult Psychiatry, Dr. Taglienti has been at Mather Hospital since 2016.  Dr. Taglienti grew up in Oklahoma, however moved to Buffalo as a teenager, and is a graduate from State University of New York at Buffalo Medical School.  She completed her Psychiatry residency at State University of New York at Stony Brook where she also served as Chief Resident for the academic year 2011-2012.  She previously worked for and taught as an Assistant Professor at the Stony Brook School of Medicine.  She also served as the Assistant Outpatient Clinic Director and Associate Residency Program Director at Stony Brook University Hospital from 2014-2016.  Passionate about teaching, she was awarded the Psychiatry Residency Faculty Teacher of the Year award in 2015 at Stony Brook.  Dr. Taglienti enjoys implementing techniques to enhance resident wellness.  She incorporated Wellness days into the core didactic curriculum in order to ensure all residents are caring for their own health needs.  She enjoys mentoring residents and has an open door policy, residents are encouraged to come in to speak with her at any time.  She frequently seeks resident feedback and makes adjustments in order to enhance the overall quality of the program.   In 2020, she was nominated and awarded as Northwell Health’s Teacher of the Year for Mather Hospital.  In her spare time, she enjoys spending quality time with her children at the aquarium, beach, and/or local museums.

Joanna Stanczak, MD is the Associate Program Director of the Psychiatry Residency Program. She serves as the adult inpatient unit psychiatric attending and outpatient resident clinic psychiatrist.  She completed her residency training at Zucker school of Medicine-Northwell Health at Mather Hospital, where she served as the 2021-2022 Chief Resident. During her time in residency, she was awarded Northwell Teacher Associate in Psychiatry.  Furthering her passion for resident wellness, she served as the Wellness Committee Co-chair from 2020 to 2022. She is also a member of the promoting physician excellence committee at Mather Hospital.  She is a Graduate of American University of Antigua School of Medicine, and a Stony Brook University Alumni. Her interests include tennis, travel, Zumba, floral design, cooking, and is a dog mother to an Australian Shepherd.

Brandon R. Theodule, MBA serves as the Program Administrator for the Psychiatry Residency Program. Brandon has worked in the healthcare industry for several years in different roles. Before coming to Mather Hospital, Brandon worked as an Operations Manager for a surgical practice on Long Island. Prior to that, he worked at South Oaks Hospital Northwell Health in Amityville, NY as a Behavioral Health Associate, while also doing Practice Management for Keep Smiling Therapy PLLC in Melville, NY.

Brandon holds a bachelor’s degree in Healthcare Administration, a Masters Degree in Business Administration, and is currently enrolled in a second Masters Degree program in Healthcare Administration at Hofstra University. He is a member of the Project Management Institute, Healthcare Financial Management Association, and American College of Healthcare Executives.

In Brandon’s spare time, he enjoys fitness, sports, outdoor activities, motorcycling, and spending time with friends and family.

Donna Donoghue, MD

Donna Osikowicz Donoghue, MD serves as Medical Director of the Mental Health Clinic and faculty member of the Psychiatry Residency Program. She serves as one of the primary inpatient psychiatry attendings supervising residents. Dr. Donoghue has been Board Certified in Adult Psychiatry since 2002 and joined Mather Hospital in 2015. A native Long Islander, Dr. Donoghue attended University of Maryland School of Medicine but returned to complete her psychiatry residency at Hillside Hospital/ Long Island Jewish Hospital where she served as Chief Resident from 1999 to 2000. Dr. Donoghue was previously Assistant Professor of Psychiatry at Stony Brook School of Medicine from 2001 to 2014 where she supervised psychiatry residents and served as Assistant Director at the Outpatient Clinic. During her time at Stony Brook, she was Associate Director of CPEP and also served as an expert witness, testifying in over 100 Assisted Outpatient Treatment cases. Dr. Donoghue has been involved in developing the psychiatry residency program since its beginnings and has taken great pride to see how far it has come under the direction of Dr. Taglienti, Dr. Chacko, and the well-rounded and dedicated faculty. Dr. Donoghue has a special interest in helping educate parents in the autism community about available resources and navigating the system. In her spare time, she enjoys crafting, traveling, and spending time with her husband and six children.

Hammad Mohsin, MD

Hammad Mohsin, MD is a core faculty member of the Psychiatry Residency Program and is a Medical Director at Chemical Dependency Clinic. He is an Assistant Professor of Psychiatry at NYU Langone health. A graduate from Nishtar Medical College, Multan, Pakistan, he completed his Psychiatry residency at Albert Einstein College of Medicine, Bronx Lebanon, where he also served as Chief Resident for the academic year 2013-2014.   He also completed two Fellowships  in Addiction Psychiatry at Albert Einstein College of Medicine, Montefiore Medical Center and Psychodynamic Psychotherapy, New York Medical College.  He is double board certified in adult and Addiction Psychiatry. Dr. Mohsin previously worked as an Assistant Professor and Medical Director at Montefiore Medical Center, Chemical Dependency program. His areas of interest and expertise is working with patients with substance use disorder and comorbid behavioral problems.

Saad Khan, DO serves as a Tele Psychiatry Attending for the Mather Hospital Northwell Health Psychiatry Residency Program. Born and raised in Smithtown, New York, Dr. Khan is a native Long Islander, who joined the department in November 2020. He completed his medical education at Western University of Health Sciences in Pomona, California. He then went on to complete his General Psychiatry Residency at Tufts Medical Center in Boston, Massachusetts, where he served as the Administrative Chief Resident during the 2016-2017 academic year. After completing his residency, Dr. Khan went on to complete his fellowship training in Consultation & Liaison Psychiatry at NYU Langone in 2018. He is board certified in both General Adult Psychiatry and Consultation & Liaison Psychiatry. He has previously worked for other health systems and served as a faculty member at the rank of Assistant Professor at Icahn School of Medicine at Mount Sinai, Baylor College of Medicine, and Texas A&M College of Medicine teaching medical students and training Psychiatry residents and fellows.


George Lasker, MD, PhD is a core faculty member of the Psychiatry Residency Program and an inpatient attending at Mather Hospital. A graduate from the Georgia Institute of Technology, he received the John H Ridley award for achievement in science during his undergraduate studies. He was a recipient of the Physician Scientist Program Scholarship at the Tulane University School of Medicine where he completed his MD as well as a PhD in pharmacology. Following medical school, Dr. Lasker attended Johns Hopkins Hospital for completion of his psychiatry residency in Baltimore, Maryland. He is board certified in Adult Psychiatry. He is active in the area of publication surrounding pharmacology, neurology and psychiatry with over 30 peer reviewed papers. His areas of interest involve teaching, utilization of new pharmacologic agents and novel modalities for treatment resistant depression. 



Zubair Ali, MD is the Chief of Consultation Liaison Psychiatry at South Shore University Hospital. Dr. Ali completed residency at Richmond University Medical Center, where he served as Chief Resident from 2017 to 2019.  As Chief Resident, he played an active role in the education of medical students and junior residents. Dr. Ali went on to complete a fellowship in Consultation Liaison Psychiatry at Stony Brook University Hospital, where he furthered his education in palliative care, neurology, critical care, and transplant psychiatry.

As chief of Consultation Liaison Psychiatry at South Shore University Hospital, Dr. Ali has expertise in delirium and psychiatric care for patients with complex medical conditions. His interests include photography, technology, and spending time with his dog, Benji.


Alan T. Kaell, MDAlan T. Kaell, MD serves as the Director of Resident Scholarly Activity and Faculty Development at Mather Hospital. Board certified in Internal Medicine, Rheumatology and Geriatrics, Dr. Kaell has been an active investigator since 1983, focusing on rheumatology and immunology, resulting in numerous published research articles and chapters. He has lectured on his findings internationally, has had privileges at 4 major hospitals in Suffolk County and has been a reviewer and editor of various national journals for over 30 years. Dr. Kaell has conducted over 20 Phase II, III and IV clinical trials for anti-rheumatic therapies and has been the recipient of NIH and Fetzer research grants. He has taught medical students, residents and fellows for the past 30 years and is currently a participant in the Academy of Rheumatology Medical Educators, whose mission is to develop, implement and assess novel teaching techniques by incorporating Patient Reported Outcomes and evaluating patient and physician behavioral changes.

Erin Dainer, MD serves as Chair of the Department of Psychiatry at Mather Hospital Northwell. Prior to joining Mather Hospital Dr. Dainer served as Regional Medical Director of Mental Health for Teladoc Health with the mission to integrate psychiatry in all aspects of medicine and to provide services to all regardless of their geographical locations.  Prior to her employment at Teladoc Health, she directed the Adult Outpatient Psychiatry Clinic, Telepsychiatry, and Integration at Stony Brook University Hospital.  While serving at Stony Brook she expanded ambulatory services from one outpatient clinic to three, and conceived and implemented its Telepsychiatry program.  She further expanded psychiatric and behavioral health integration services to encompass adult primary care clinics as well as subspecialty and pediatric clinics.  Within the Family Medicine clinics, she implemented collaborative care services.

Dr. Dainer earned her Bachelor of Sciences degree in Biology with highest honors from Georgia Institute of Technology and her MD from the Medical College of Georgia.  She trained in Internal Medicine and Psychiatry at Tulane University, which led to board certification in both specialties.

As Department Chair of Psychiatry at Mather Hospital, Dr. Dainer will have oversight of psychiatric services and will identify and develop new clinical programming to enhance access and utilization of high-quality psychiatric care.


Greg Haggerty, Ph.D., received his B.A. in psychology from St. John’s University and his Ph.D. in clinical psychology from Adelphi University. His completed his APA-Accredited clinical psychology internship at Zucker Hillside Hospital/Northwell Health (formally North Shore-LIJ Health System) and received post-doctoral research training at Zucker Hillside Hospital’s Division of Psychiatric Research. Dr. Haggerty has served as the director of research for Nassau University Medical Center’s Psychiatry department and was chair of the hospital’s Institutional Review Board (IRB). He has worked as chief psychologist for NUMC’s adolescent inpatient unit and as supervising psychologist in NUMC’s adult outpatient clinic where he supervised child and adolescent psychiatry fellows, psychiatry residents, psychology externs and psychology interns (as part of an APA-accredited psychology internship). He maintains an active research program focusing on personality assessment, training, psychopathology classification, and treatment outcome. Dr. Haggerty has received funding for his research from the NIMH and American Psychoanalytic Association and has active research collaborations with Massachusetts General Hospital, University of Michigan, St. John’s University, Adelphi University and Austin Riggs Hospital.