Philip Sullivan, MD

Staff Psychiatrist
Languages
English
Conditions Treated
Anxiety
Bipolar Disorder
Depression
Obsessive-compulsive disorder (OCD)
PTSD/Trauma
Geriatric

Education and training

  • University of Rhode Island, BS
  • Brown University Medical School, MD
  • The Waltham Hospital, Internship
  • Massachusetts Mental Health Center, Residency and Fellowship

Get to know

Philip Sullivan, MD

*THIS PROVIDER CANNOT PRESCRIBE CONTROLLED SUBSTANCES FOR NH PATIENTS* Doctor Phillip Sullivan is a staff psychiatrist at Talkiatry. He is board certified in both adult psychiatry and child and adolescent psychiatry. His interest in psychiatric treatment was originally triggered by the humanistic writings of Abraham Maslow, Carl Rogers, and Rollo May. As he earned his medical degree and started post-graduate psychiatric training, he went on to learn psycho-pharmacological, cognitive-behavioral, and psychodynamic treatment approaches. He combines these perspectives in diagnosing and treating psychiatric conditions including depression, bipolar spectrum disorders, anxiety, stress and trauma related disorders, adjustment problems, maternal mental health, OCD, ADHD and other disorders. His practice focuses on supportive pharmacological treatment, and he sees listening and empathy as essential elements of the treatment process. He strives to provide a comfortable experience in which doctor and patient work together to understand the presenting problems, develop a treatment plan, reduce symptoms, and optimize functioning. Doctor Sullivan supports and encourages concurrent psychotherapy and will work collaboratively with therapists to optimize the best treatment results. Doctor Sullivan received his MD degree from Brown University Alpert School of Medicine. After completing a medical-surgical internship, he went on to a residency in adult psychiatry and a fellowship in child and adolescent psychiatry at Harvard Medical School's Massachusetts Mental Health Center. He has held academic appointments at Harvard Medical School and the University of New England School of Osteopathic Medicine. In the 36 years following completion of his training, he has worked as the medical director of a mental health center on the under-served Eastern Shore of Maryland, as the medical director of a child and adolescent psychiatric inpatient unit, as a staff psychiatrist at New Hampshire's Dartmouth Hitchcock Clinic, and as the medical director of child and adolescent psychiatric services at Concord New Hampshire's mental health center. Before joining Talkiatry, he served for 18 years as the chief of psychiatry at Southern New Hampshire Medical Center where he also spent three years as the hospital's chief of staff.

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Dr. Ruiz is a compassionate psychiatrist specializing in adult and maternal mental health. She develops personalized treatment plans to address anxiety, depression, bipolar disorder, ADHD, OCD, PTSD, PMDD, and perinatal conditions. Her goal is to help patients reconnect with their values and live balanced, fulfilled, and meaningful lives.

Her passion for medicine began in childhood, inspired by curiosity about the mind and body. She earned an Honors Chemistry degree with  magna cum laude and completed her medical training and psychiatry residency at Texas Tech University Health Sciences Center. With a strong scientific foundation, Dr. Ruiz understands the role of medications, and embraces holistic healing through connection, gratitude, and spirituality.

Dr. Ruiz has experience in diverse clinical settings and has received national awards including the AWP International Fellowship and ADMSEP Innovations Award. She is dedicated to advancing maternal mental health screening and treatment through clinical care and education.

Dr. Ruiz combines pharmacotherapy (medication) with psychotherapy to create individualized treatment plans. Therapy provides powerful tools to manage thoughts, emotions, and behaviors that support balanced brain chemistry. Research shows that medication helps restore this balance more quickly and effectively, especially in moderate to severe cases.  

Dr. Ruiz likens medication for the brain to fertilizer for a garden. Imagine your mental health as a vibrant garden—when well-nourished, it can thrive with resilience, beauty, and balance. But when symptoms like depression, anxiety, ADHD, or mood instability take hold, they act like invasive weeds, crowding out healthy growth and making it hard to enjoy the space. Medication acts like fertilizer, strengthening the garden’s natural systems so the healthy parts can reclaim their place and flourish. Just as some gardens need only seasonal care while others require more consistent tending, medication plans are personalized to support each person’s long-term mental wellness. When the garden is healthy, there's more room to grow, connect, and fully enjoy life.

With a strong background in chemistry and pharmacology, Dr. Ruiz prioritizes educating her patients about how medications work and why they can be helpful. She believes patients should take an active role in understanding their diagnosis and treatment. Her approach emphasizes diagnostic clarity, medication management, patient education, and brief psychotherapy based on cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT).

Your first appointment is a supportive, in-depth conversation to share your story, challenges, and goals. Dr. Ruiz will review your medical and psychiatric history and assess symptoms using a whole-person approach that considers biological, psychological, and social factors.

Together, you’ll develop a personalized plan that may include lab work, medication, and therapy. Initial visits last 60 minutes for thorough evaluation; follow-ups typically last 20–30 minutes, focusing on medication management and brief therapy. If needed, Dr. Ruiz can refer you to in-house or community therapists for add-on therapy support.  

Throughout your care, Dr. Ruiz prioritizes shared decision making to ensure you feel informed, empowered, and supported.

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Staff Psychiatrist

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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Staff Licensed Mental Health Counselor

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Tyler O'Brien, MD

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Dr. O'Brien is a board-certified adult psychiatrist who completed his medical education at Northeast Ohio Medical University. Following his graduation from NEOMED, he completed a residency in Psychiatry and Behavioral Medicine at West Virginia University/Charleston Area Medical Center. Throughout his training, he has enjoyed working in both outpatient and hospital settings and has a great passion for medical education and teaching the next generation of mental healthcare providers. Dr. O'Brien's practice focuses on medication management for a wide variety of mental health diagnoses, including anxiety disorders, depression, Bipolar Disorders, Obsessive Compulsive Disorder, Tic Disorders, and Post Traumatic Stress Disorder. In addition to medication, he offers a mixture of Cognitive Behavioral Therapy, Dialectical Behavioral Therapy, and Psychodynamic Therapy during 30 minute follow up appointments. Dr. O'Brien believes in a truly collaborative and holistic approach to mental healthcare, striving to involve patients and all members of the healthcare team in every aspect of care.‍

Elizabeth Shaffer, MD

Staff Psychiatrist

Elizabeth Shaffer, MD, is an accomplished psychiatrist specializing in child and adolescent psychiatry. She earned her M.D. degree from St. George's University School of Medicine and holds a Bachelor of Science in Child Development from Appalachian State University where she graduated summa cum laude. Dr. Shaffer's passion for working with children and families developed during her involvement in a pre-K Head Start Program in Rural North Carolina. She completed her General Psychiatry Residency and Child & Adolescent Psychiatry Fellowship at Jerry M. Wallace School of Osteopathic Medicine at Campbell University. Dr. Shaffer obtained ABPN Board Certification in General Psychiatry in 2023 and is working towards Board Certification in Child & Adolescent Psychiatry. Dr. Shaffer has received honors and awards for her contributions to psychiatry, including the Laughlin fellowship through The American College of Psychiatrists and Resident of the Year at Cape Fear Valley Health System in 2022.Her areas of interest focus on neurodevelopmental disorders such as ADHD, Autism, and Intellectual Delay. Dr. Shaffer is affiliated with professional organizations like AACAP and APA, demonstrating her commitment to professional development. Dr. Shaffer is dedicated to promoting mental health awareness and family and patient psychoeducation. Dr. Shaffer emphasizes a joint decision-making approach to treatment options and utilizes local resources to provide wrap-around support. Dr. Shaffer is a respected psychiatrist known for her excellence, compassion, and innovative approach to mental health care. Her extensive education, accolades, research contributions, professional affiliations, and community involvement reflect her commitment to making a positive impact in her patients' lives and the broader community.

Mustafa Taquee, MD

Staff Psychiatrist

Dr. Mustafa Taquee is a board-certified Adult Psychiatrist. After receiving his undergraduate degree from Wayne State University in Detroit, he completed his medical degree at Oakland University William Beaumont in Rochester, MI. He is a graduate of the Adult Psychiatry Residency Program at St. Mary Mercy Hospital in Livonia, MI. As a testament to Dr. Taquee's desire to help patients reach their full potential, he has also completed a psychotherapy fellowship through the Michigan Psychoanalytic Institute. Dr. Taquee believes that every patient brings their own mosaic of experiences embedded in a unique story. He understands that building a strong therapeutic relationship through empathy, compassion, trust, and respect is essential. He enjoys taking time to understand his patient's goals, offer psychoeducation, and create a collaborative plan for treatment with the patient. He believes in a holistic approach to mental health treatment, which includes medication management, supportive and cognitive behavioral therapy techniques, as well as mind-body medicine techniques. He also has a special interest in psychodynamic therapy, an in-depth therapy modality, which he incorporates in all patient interactions and sessions. Due to the diversity and richness of culture in southeast Michigan, Dr.Taquee has experience working with patients from varied backgrounds. He enjoys the challenge such a heterogeneous environment brings and is particularly fond of working with young adults experiencing life transitions. He also has experience working with patients from lower socioeconomic backgrounds, as well as adolescents and geriatric populations.

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Specialties
Anxiety
Bipolar Disorder
Depression
Obsessive-compulsive disorder (OCD)
PTSD/Trauma
Geriatric
States
Massachusetts
Florida
New Hampshire
New York
Languages
English
Takes insurance
Virtual visits
36 years experience