Shaneika Lindsay, PMHNP

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. Deringer is a psychiatrist with board certification in general psychiatry and addiction psychiatry. She earned her M.D. from the University of Michigan Medical School, and she completed her psychiatry residency and addiction psychiatry fellowship training at New York University. She has previously held faculty roles at New York University School of Medicine and Harvard Medical School. She has been involved in training the next generation of psychiatrists through her past work on the Program Director team for the MGH-McLean Psychiatry Residency Program. She has expertise in treating adults with mood disorders, anxiety disorders, substance use disorders, personality disorders, trauma, and ADHD.

Dr. Deringer cares deeply about understanding each patient's unique experience.  She recognizes that mental health symptoms are impacted by an individual's biological make-up, social situation, and their individual way of interacting with others in the world.  She will assess all of these factors and work with you to develop an appropriate treatment plan to help you feel better and meet your goals.  She incorporates supportive psychotherapy into all of her patient meetings; this may include discussions of the role of nutrition, exercise, and sleep habits in your overall well-being.

Dr. Deringer will begin the evaluation process with a thorough one-hour session in which we will discuss your current symptoms, your prior treatment history, your medical history, and your goals for treatment.  At the end of that session, she will begin to formulate her diagnostic impression and treatment recommendations.  Sometimes, the evaluation process may require more than one session, and it may be helpful for Dr. Deringer to gather information, with your permission, from prior treatment or to collaborate with your therapist if you have one.  Dr. Deringer will work with you on a medication treatment plan, if clinically indicated, to help you manage your symptoms and achieve your treatment goals.

Dr. Jordan Kalosieh has experience treating patients across the lifespan in a variety of clinical settings, including inpatient, intensive outpatient, rehabilitation, and outpatient care. She earned her medical degree from St. George’s University School of Medicine and completed her psychiatry residency at HCA Aventura Hospital, where she served as chief resident.

Dr. Kalosieh believes in open and transparent communication, offering guidance while respecting each patient’s autonomy. She values authenticity in the therapeutic relationship, combining warmth with directness to create a calm, attentive, and nonjudgmental environment where patients feel supported and understood.

Dr. Kalosieh takes a holistic approach, carefully considering each patient’s unique history, needs, and goals when creating treatment plans. She emphasizes shared decision-making by clearly communicating her thought process and engaging patients as active partners throughout their treatment journey.

Dr. Sallie Jo Hadley holds the position of Staff Psychiatrist at Talkiatry. She is board-certified in psychiatry and pediatrics and is board-eligible in child and adolescent psychiatry. She has been practicing for 22 years. Dr. Hadley's practice is focused on medication management with supportive therapy in follow-up sessions of 15 or 30 minutes. Dr. Hadley is experienced with collaborative treatment and encourages adding a therapist to your care team in those situations where additional therapy might be helpful. Dr. Hadley is a graduate of the Mount Sinai School of Medicine's triple-board program (psychiatry, pediatrics, and child and adolescent psychiatry). She completed post-doctoral research fellowships at Mount Sinai's Seaver Center for Autism Research/Compulsive-Impulsive Anxiety Disorders and at Columbia University's New York State Psychiatric Institute, the latter focusing on metabolic and weight issues in children and adolescents with psychiatric disorders. Dr. Hadley had an early background as a nurse, receiving her B.S. in Nursing from the University of North Carolina-Chapel Hill. Her experience in neonatal, psychiatric, and hospice nursing led her to pursue her degree in medicine. Dr. Hadley has worked in pharmacologic research in both academic and industry settings. Prior to joining Talkiatry, she practiced in a multi-specialty clinic for individuals and families dealing with autism or intellectual disabilities and complex medical co-morbidities. Dr. Hadley enjoys working with motivated individuals of all ages who are seeking to better their life or better cope with life circumstances. She has particular expertise in working with individuals and their families suffering from anxiety, depression, and obsessive-compulsive disorders.

Nan Ambrosy is a PMHNP with over 23 years of experience in outpatient and inpatient settings, caring for patients across the lifespan with a wide range of diagnoses. She earned her Doctor of Nursing Practice from Graceland University and holds master’s and post-graduate certificates from Wichita State University. She is ANCC board-certified as both an Adult Psychiatric Clinical Nurse and Lifespan Psychiatric Nurse Practitioner.

Nan uses a patient-centered approach with shared decision-making, fostering strong therapeutic relationships. She focuses on the whole person, emphasizing a balanced lifestyle that includes physical health, sleep, nutrition, exercise, social connections, and spirituality.

She begins with a thorough biopsychosocial assessment and collaborates with patients to set treatment goals. Using clinical judgment and diagnostic criteria, she develops individualized plans, discussing evidence-based treatment options such as therapy and medications. Follow-ups include ongoing monitoring to assess progress and refine goals as needed.

Dr. Tiffany Abtahi is board certified in adult psychiatry and has been in practice for over 6 years. She completed her residency at Icahn School of Medicine, Elmhurst Hospital Center program where she served as Chief Resident in her final year. After completing her residency training, Dr Abtahi worked as a staff psychiatrist in the VA Medical Center focusing on PTSD, depression, and anxiety. Dr. Abtahi has held an academic appointment at the University of UT Southwestern medical school and has spent her professional career supervising/teaching medical students and psychiatry residents. Dr. Abtahi's practice focuses on medication management and providing psychoeducation to her patients. However, if indicated, Dr. Abtahi may believe that additional therapy is also needed and ask that you bring a therapist into your care team to provide the best outcome. Dr. Abtahi has experience treating a large variety of mental health conditions across a variety of populations. She strongly believes in tailoring treatments through a holistic and patient-centered approach based on individual and multi-faceted histories. Dr. Abtahi looks forward to working with you.