Kristina Schnitzer, MD

Douglas Brennan, MD, earned his medical degree from the University of Colorado School of Medicine and completed an adult psychiatry residency at Massachusetts General Hospital (MGH) and McLean Hospital. He also completed a forensic psychiatry fellowship at MGH. Dr. Brennan has experience in both outpatient and inpatient settings, supervising residents and mid-level practitioners, and working in emergency and inpatient facilities. He remains on staff at MGH as an instructor for Harvard Medical School and is double-board certified in adult and forensic psychiatry. His outpatient work includes several years treating patients at the Department of Veterans Affairs with post-traumatic stress disorder, depression, and anxiety.

Dr. Brennan enjoys collaborating with patients to understand their goals, set expectations, and provide education on treatment options. He offers medication management evaluations and follow-up visits while working alongside licensed therapists to provide behavioral support as needed.

Dr. Brennan begins by thoroughly reviewing each patient’s history, concerns, and goals in the initial session. He then develops individualized treatment plans tailored to the patient’s objectives, ensuring care aligns with their personal goals and needs.

Getting to know meDr. Kishan Peddanna is a board-certified general psychiatrist with experience treating patients across the lifespan. He attended The Ohio State University for his undergraduate studies and earned his medical degree from the University of Cincinnati. Dr. Peddanna completed his residency in General Psychiatry at The Ohio State University and a fellowship in Child and Adolescent Psychiatry at Nationwide Children’s Hospital.

Dr. Peddanna values continuity of care and collaboration, working with patients toward long-term improvements while building meaningful connections. His approach is grounded in shared decision-making, ensuring treatment plans align with each patient’s goals. He has extensive experience managing conditions such as ADHD, mood disorders, and anxiety.

Dr. Peddanna’s practice focuses on medication management complemented by supportive psychotherapy. He uses evidence-based assessments and interventions to guide individualized treatment planning, fostering a care experience that is both effective and patient-centered.

Xavier Diao, MD (he/him) is a board-certified psychiatrist. He earned his undergraduate degrees in Psychology and Biological Sciences at the University of Maryland, where he also obtained his medical degree. Dr. Diao completed his psychiatry residency at the Icahn School of Medicine at Mount Sinai, received additional training in child and adolescent psychiatry at Columbia and Cornell, and finished a psychoanalytic fellowship at the New York Psychoanalytic Society & Institute. Prior to joining Talkiatry, he was an Assistant Professor of Clinical Psychiatry at the University of Pennsylvania, where he provided clinical care and teaching along the undergraduate-graduate medical education continuum.

Dr. Diao's therapeutic orientation is informed by psychodynamic, cognitive behavioral, and dialectical behavior modalities. He has expertise in the treatment of a diverse range of mental health conditions, including depression, anxiety, OCD, and PTSD. Dr. Diao uses a developmentally informed and LGBTQ-affirmative approach in his practice, with the aim of enriching meaning and alleviating suffering in the domains of work, play, and love.

Dr. Diao begins each encounter with gentle curiosity, inviting patients to share their stories without fear of judgment. Together, he crafts an individualized treatment plan with the patient that may include medication, psychotherapy, and/or referrals to subspecialty care, always in close collaboration with other members on the treatment team.

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Margaret Ngumi, MSN, APRN, FNP-C, PMHNP-BC, is a dual board-certified Psychiatric Mental Health and Family Nurse Practitioner with over 20 years of experience in healthcare. She began her career as a Family Nurse Practitioner and later pursued a post-master’s certification in psychiatry to address the growing need for accessible mental health services. Margaret has extensive experience in both inpatient and outpatient settings, treating conditions such as depression, anxiety, PTSD, mood disorders, and substance use disorders.

She takes a collaborative, patient-centered approach to care, creating a safe and supportive environment where individuals feel heard and empowered. With a strong emphasis on holistic care, Margaret considers all aspects of a patient’s well-being—including lifestyle, relationships, and overall health. Whether through medication management, therapy, or lifestyle modifications, she is committed to helping patients achieve meaningful and lasting improvements in their mental health.

Margaret begins with a comprehensive psychiatric evaluation to understand each patient’s history, concerns, and goals. She then works closely with them to develop a personalized care plan that may include medication, therapy, and evidence-based lifestyle interventions. She prioritizes open communication, patient education, and ongoing collaboration to ensure treatment remains effective and evolves with each patient’s needs. Through her compassionate and evidence-based approach, Margaret is dedicated to helping individuals find balance and improve their overall quality of life.

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Dr. Bryce Toburen is a board-certified psychiatrist dedicated to compassionate, collaborative care across the lifespan. His training includes an MD from the Medical College of Wisconsin, residency at The Ohio State University where he served as Chief Resident, and a fellowship in Child & Adolescent Psychiatry at Nationwide Children's Hospital. Outside the clinic, he enjoys sports, tennis, exploring nature, traveling, and spending time with loved ones.

Each patient brings a unique story, and he strives to create a safe, respectful space where you feel heard and supported. His interest in psychiatry stems from a desire to maximize the well-being of patients and their families through strong therapeutic relationships. Compassion and curiosity guide his work, along with a strong belief in the power of connection and collaboration. You can expect open communication and a focus on your personal goals throughout your time together.

Treatment is personalized using evidence-based approaches that include psychotherapy, medication management, and lifestyle strategies. He specializes in addressing anxiety, depression, ADHD, OCD, and trauma-related concerns. Collaboration and trust are central to his approach, with an emphasis on empowering patients to take an active role in their healing and well-being.

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Dr. Jeffrey Seley is board certified in adult psychiatry. He has been in practice for over 21 years. Dr. Seley's practice focuses on medication management in conjunction with supportive therapy and psychoeducation in 20-30 minute follow-up visits. At times, Dr. Seley may recommend additional therapy and ask that you bring another therapist into your care team to provide the best outcome. Dr. Seley graduated from Cornell University with a B.A. degree in psychology. He received his medical degree from the University of South Florida and completed his residency at New York University and its affiliated hospitals, including Tisch and Lenox Hill, where he served as chief resident. He has worked for over twenty years in private practice and at a large community hospital in Pennsylvania. His extensive hospital experience kept him sharply focused on the connection between medical issues and mental health presentations. Dr. Seley brings to his patients over twenty years of experience in general adult psychiatry treating a wide variety of conditions including depression, anxiety, bipolar disorder, ADHD, addiction, and geriatric issues. His treatment philosophy stresses the importance of being responsive, compassionate, and kind. He sees his work as the enhancement of hope.