Saisha Saint-Cyr, MD

Background and credentials    

Dr. Catherine Cashman is triple board-certified by the American Board of  Psychiatry and Neurology in Adult Psychiatry, Child & Adolescent  Psychiatry, and Forensic Psychiatry. She holds two Bachelor’s degrees: one in  Finance from New York University, and another in Biology from the University  of New Orleans. She earned her medical degree from Nova Southeastern  University and completed an Adult Psychiatry residency at LSU Health Sciences  Center in New Orleans. Dr. Cashman subsequently completed two fellowships:  the first in Child & Adolescent Psychiatry at LSU New Orleans, along with  a certification in Infant Mental Health (working with children ages 0–6 years  and their caregivers); the second fellowship was in Forensic Psychiatry at  the University of Rochester and the Rochester Regional Forensic Unit.    

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Treatment approach    

Dr. Cashman brings an extensive and specialized skillset to psychiatry,  informed by her triple board-certifications. Her treatment approach  integrates clinical expertise from adult, child and adolescent, and forensic  psychiatry, emphasizing accurate diagnosis, risk assessment, and  evidence-based care. With specialized expertise in forensic psychiatry and  competency assessments, she employs rigorous evaluation methods to accurately  inform treatment planning and risk management, particularly in complex or  legally-involved cases.    

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What you can expect in a first visit    

Patients visiting Dr. Cashman for the first time can expect a detailed and  comprehensive psychiatric evaluation. Given her forensic and clinical  experience, initial assessments are thorough, focusing on clear diagnostic  understanding, individualized risk assessment, and appropriate treatment  planning. Patients can anticipate a collaborative, professional, and  structured environment aimed at clarifying diagnoses and addressing their  unique mental health needs effectively.    

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Why Talkiatry?    

We’re a virtual mental health practice that makes it easy to find great  care. We combine quality and convenience to help you thrive—faster. Our  providers, like this one, are highly trained experts who specialize in  medication management and collaborate with you on a treatment plan that fits  your needs and comfort level.

Lance Briggs is a dedicated Psychiatric Nurse Practitioner with over a decade of clinical and leadership experience. A graduate of the University of North Dakota, Lance began as a psychiatric RN in acute inpatient settings before becoming a psychiatric RN supervisor in a major Houston hospital while pursuing advanced practice.

After becoming a PMHNP, Lance initially worked with outpatient addiction treatment and severe mental illness populations, later expanding into bariatric psychiatry to support patients preparing for weight-loss surgery. When the COVID-19 pandemic paused bariatric procedures, Lance founded a private practice—Grey Matters Mental Health—in Seattle, which was later sold to a larger healthcare organization in Minnesota. Lance then transitioned into correctional mental health, serving underserved populations within the criminal justice system. Currently, Lance is working at Talkiatry, providing compassionate, high-quality care informed by experience across diverse and challenging environments.

Lance understands that every patient is unique. His approach is grounded in Carl Rogers’ principle of unconditional positive regard, creating a safe, calming space where patients feel heard and valued. Lance takes time to explore developmental history, family background, and major life events, recognizing how past experiences shape present challenges. He aims to understand each symptom fully and offers thoughtful, collaborative treatment options.

Dr. Alfers is a board-certified psychiatrist specializing in adult psychiatry. He has been practicing for over 11 years. He completed his undergraduate education at Virginia Tech, graduating Cum Laude with degrees in Biology and Chemistry. Following graduation, he attended a research internship at the National Institutes of Health where he received a Post-baccalaureate Intramural Research Training Award. Dr. Alfers completed his medical degree from the Western University of Health Sciences in Pomona, CA. He completed his General Psychiatry Residency at Georgetown University, where he served as Chief Resident. After residency, he entered private practice in McLean, VA. Dr. Alfers takes a comprehensive approach to patient care. He integrates biological, psychological, and environmental factors into treatment planning. He focuses on developing a meaningful therapeutic relationship and providing medication interventions for specific treatment goals. Dr. Alfers provides interpersonal psychotherapy in conjunction with medication management services. Dr. Alfers has a special interest in the treatment of multiple mental health conditions, including depression, anxiety, bipolar disorder, PTSD, ADHD, and OCD. Dr. Alfers treats adults ages 18 to 65 years old. For established patients of Dr. Alfers, please call 917-634-5311 to schedule an appointment and let the care coordinator know you are an established patient.

Dr. Kira Posteraro is double board-certified in Adult and Addiction Psychiatry and has over 10 years of clinical experience. She completed her General Adult Psychiatry Residency at Allegheny General Hospital in Pittsburgh, PA, followed by a fellowship in Addiction Psychiatry at Beth Israel Medical Center in New York, NY.

Dr. Posteraro’s career has included serving as Director of Psychiatric Services at an addiction treatment center in Pittsburgh, PA, where she provided care across the full continuum of substance use disorder treatment—including residential, acute PHP, IOP, outpatient, and aftercare services. She later held the role of Section Chief Psychiatrist for the Center for Treatment of Addictive Disorders at VA Pittsburgh Healthcare System, offering both residential and outpatient services and acting as Medical Director for the SAMHSA-certified Opioid Treatment Program. Most recently, she served as Chief of Psychiatry for the Behavioral Health Service Line at VA Pittsburgh, where she had the honor of caring for our nation’s Veterans.

While her clinical expertise centers on the diagnosis and treatment of substance use disorders, Dr. Posteraro also has extensive experience treating a wide range of psychiatric conditions, including depressive and bipolar spectrum disorders, anxiety disorders, and trauma-related disorders.

Dr. Posteraro uses a collaborative, supportive approach to care, incorporating motivational interviewing to help guide patients on their journey to wellness. She integrates holistic strategies alongside medication management and is dedicated to meeting patients where they are in treatment to build individualized, effective recovery plans.

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Dr. Mousavi holds the position of attending psychiatrist at Talkiatry. She is Board certified in adult psychiatry and has been practicing for over 6 years. Dr. Mousavi's practice focuses on medication management. Typically, she offers this in conjunction with supportive therapy in 30-minute follow up visits. Dr. Mousavi may believe that additional therapy is also needed and ask that you bring a therapist into your care team to provide the best outcome. She has completed her residency at Westchester Medical Center/New York Medical College. She has experience of working in private practice at the Institute for Family Therapy in Miami. She has also worked as an outpatient psychiatrist at Montefiore in NY and INOVA outpatient clinic in Virginia.

Dr. Tetyana Tarnavsky is a board-certified psychiatrist trained in Adult Psychiatry. She attended Dnipropetrovsk State Medical Academy in Ukraine where she received her M.D., M.S. and Ph.D. degrees in Psychiatry. Dr. Tarnavsky completed her residency at Harvard South Shore Psychiatry Residency Training Program in MA, where she was elected chief resident. Dr. Tarnavsky has an extensive research experience in Ukraine and the USA. She had studied computer addiction for her dissertation; had multiple abstracts and presentations; published several articles in peer-reviewed psychiatric journals as well as a book entitled Computer Addiction: Formation, Diagnosis, Correction and Prophylaxis. She has helped organize international conferences with the goal of improving access to and quality of healthcare in Dnipropetrovsk, Ukraine, and providing a national model for health care reform. Dr. Tarnavsky has worked with a variety of patients with diverse backgrounds in a Community Health Center and in the Partial Hospitalization Program as well as supervised medical students, psychiatry residents, and nurse practitioners. She has been a lecturer on psychiatry at Harvard Medical School and was involved in the training of psychiatry residents in the Harvard South Shore Psychiatry Training Program. Her primary focus has been on treating adults with depression, anxiety, post traumatic stress disorder, adjustment disorder, ADHD and other disorders. Dr. Tarnavsky strives to provide quality and compassionate treatment to individuals and their families.‍