Felicitas Koster, DO

Staff Psychiatrist
Languages
English
Conditions Treated
Medication Management

Education and training

  • A.T. Still University, Kirksville College of Osteopathic Medicine Medical Doctor/Osteopathic Doctor (MDDO)

Get to know

Felicitas Koster, DO

Dr. Koster is board certified in psychiatry and forensic psychiatry. After completing her medical education, residency, and fellowship, she started working on a Forensic Assertive Community Treatment (FACT) team, followed by working at a community hospital. She then transitioned to a clinic serving patients who were determined severely mentally ill (SMI). Dr. Koster has been involved with teaching residents and working within an academic institution. Dr. Koster is a Fellow of the American Psychiatric Association, a member of the American Academy of Psychiatry and the Law and the American Osteopathic Association. Dr. Koster enjoys working with people of diverse backgrounds and experiences. She uses a culturally sensitive and holistic approach in the evaluation and treatment of brain health conditions. She believes in a team approach and her patients' active participation in treatment planning. She incorporates a variety of modalities in her treatment that can include medications, personal medicine, psychotherapy, mindfulness, and lifestyle changes. Dr. Koster specializes in psychopharmacology and believes in using medications when indicated at the lowest effective dose to minimize the risk of side effects. She is experienced in treating depression, bipolar disorder, anxiety disorders, OCD, PTSD and schizophrenia. If Dr. Koster believes you would benefit from additional therapy, she will collaborate with your therapist to achieve the best outcome.

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Jennifer Phillips, LCSW

Staff Therapist

Jennifer Phillips is a Licensed Clinical Social worker who has worked in the mental health field since 2013.  During graduate school, Jennifer completed her internships at the Tuscaloosa County jail, the University of Alabama Student Veterans Center, and the Birmingham Veteran’s Affairs Medical Center in their Health Care for Homeless Veterans program.  Jennifer went to undergraduate and graduate schools in Alabama and moved to Arizona in 2013 to work with the Department of Veterans Affairs to continue working with homeless veterans.  Jennifer also has experience teaching at Pima Community College and is a clinical supervisor for associate level clinicians through the Arizona Board of Behavioral Health Examiners.  

Jennifer’s prior working experience and training has been with adults, homeless veterans, Native Americans, LGBTQIA, women, and individuals in rural or remote areas, providing access to much needed mental health services in provider shortage areas.  She enjoys working with patients who have anxiety, depression, insomnia, mood disorders, and self-esteem issues.  She is trained in geriatrics and especially loves working with adults over the age of 65.  

Jennifer is trained in Cognitive Behavioral Therapy, Cognitive Behavioral Therapy for Insomnia, Dialectical Behavioral Therapy, Mind-Body Approach, Mindfulness-Based Therapy, and Prolonged Grief Disorder (where the patient is experiencing grief for at least 12 months).  As she is trained in several different treatment modalities, Jennifer can customize therapy to meet everyone’s needs.

Sara Mateo, MD

Staff Psychiatrist

Dr. Sara Mateo holds the position of staff Psychiatrist at Talkiatry. She is a board-eligible adult Psychiatrist. Dr. Mateo completed her Medical degree at the University of Benghazi- Faculty of Medicine and finished General Psychiatry Residency training at Tower Health/DrexelPhoenixville Hospital. Throughout her career, Dr. Mateo has actively contributed to various leadership roles and committees, demonstrating her commitment to advancing medical education and promoting diversity in the field. During her training, she generously shared her knowledge through educational presentations and lectures, fostering the growth of fellow trainees and medical students. Dr. Mateo is dedicated to creating a therapeutic environment characterized by warmth, empathy, and nonjudgmental support. Her approach involves collaborating with patients to develop individualized treatment plans that consider cultural, biological, psychological, and social factors. With a primary focus on medication management, Dr. Mateo's keen interest in psychotherapy is evident, as she often integrates supportive therapy, cognitive behavioral therapy, and psychodynamic psychotherapy during 30-minute follow-up visits to optimize wellness and recovery. Dr. Mateo brings a wealth of experience in caring for individuals of diverse ages and backgrounds, adeptly addressing a wide spectrum of conditions. Her expertise extends to treating depressive disorders, bipolar disorders, anxiety disorders, trauma and stress related disorders, ADHD, OCD, Insomnia, psychotic disorders; she also has experience treating individuals with medical comorbidities.

Ashlyn Tellers, PMHNP

Staff Nurse Practitioner

Dr. Ashlyn Tellers is a board certified Psychiatric Mental Health Nurse Practitioner. She received her Doctorate degree in nursing with an emphasis in psychiatry, in 2020 from the University of Arizona. She has been caring for mental health patients for twelve plus years in the long-term care, inpatient, residential, and outpatient settings. She specializes in treating adults with depression, anxiety disorders, bipolar disorder, ADHD, and OCD with medication management and supportive therapy. She focuses on educating her patients to build a therapeutic and safe treatment plan with every patient. Dr. Tellers encourages her patients to discuss their past mental history and current stressors to finding the root cause of their triggers and identify healthy coping skills, while also referring patients to therapists for more specialized therapies.

Kristen Soukup, LCSW

Staff Therapist, Clinical Lead

Kristen Soukup, LCSW is a mental health therapist at Talkiatry. Kristen completed her undergraduate degree at the University of Rochester where she studied Psychology and Brain & Cognitive Science. She then went on to pursue her Master's degree in Social Work at the State University of New York at Buffalo. After completing her Master's degree, Kristen began working at an outpatient cancer center where she provided care coordination and therapeutic support to patients and their families enduring cancer diagnoses, treatments, and end of life. She then worked to pursue her clinical license in working with adults with significant and persistent mental illness in an outpatient setting. Kristen functioned not only as a primary therapist but also as the crisis team leader, providing supervision to other clinicians and assisting clients both in the clinic and the community. Kristen believes in looking at the whole person in their environment when working with her patients. She comes from a nonjudgmental and empathetic standpoint and genuinely wants to put the patient's goals and values first. Kristen has experience in treating patients with anxiety, depression, OCD, Bipolar disorder, and personality disorders. Kristen is trained in Dialectical Behavioral Therapy and tends to utilize Cognitive Behavioral Therapy techniques in treatment. She has knowledge and interest in human motivation and performance related issues, and utilizes Motivational Interviewing and mindfulness skills to assist her patients with these concerns. Kristen also has training in treating anxiety and Obsessive Compulsive disorders and uses exposure therapy to assist patients in overcoming these struggles.‍

Joel Witherspoon, LCMHC

Staff Therapist

Joel Witherspoon is a licensed Clinical Mental Health Counselor with over 20 years of clinical experience working in various mental health settings, working directly with clients from diverse backgrounds living with a broad range of mental health conditions. Joel earned his Undergraduate degree at California State University Long Beach, Graduate School at East Carolina University, Greenville, NC, and completed his internship in Raleigh, NC. Joel has been practicing for 19 years as a Licensed Clinical Mental Health Counselor, focusing on mood disorders, trauma, situational adjustment disorders, and any life challenge that interferes with a client's happiness. Working with Joel, treatment is specific to the individual with the focus on modalities that are specific to each person's challenges. Joel uses an eclectic approach with a foundation in person-centered therapy, cognitive behavioral therapy, dialectical behavioral therapy, interpersonal therapy, and trauma therapy combined with somatic interventions such as mindfulness.

Alexander Wittenberg, DO

Staff Psychiatrist

Background and credentials    

Dr. Alexander Wittenberg is a board-certified adult psychiatrist. He received his undergraduate degree from Cornell University, majoring in Human Biology, Health, and Society. He earned his medical degree from the New York Institute of Technology College of Osteopathic Medicine, where he was a  member of the Psi Sigma Alpha Osteopathic Honor Society. As chief resident at  Mount Sinai Beth Israel, he gained extensive experience working in outpatient  settings and managing patient care at one of New York City's busiest clinics. Dr. Wittenberg has expertise in treating a wide range of mental health conditions, including depressive disorders, anxiety disorders, bipolar disorder, trauma and stressor-related disorders, and OCD.    

Treatment approach    

Dr. Wittenberg offers highly individualized and empathic treatment, primarily focusing on medication management. He frequently recommends integrating therapy into treatment plans and may suggest collaborating with a therapist. Dr. Wittenberg prioritizes a holistic approach, emphasizing overall well-being alongside symptom relief. He encourages the incorporation of mindfulness, self-compassion, exercise, nutrition, and attention to interpersonal relationships into his treatment strategy.    

What you can expect in a first visit    

During an initial visit with Dr. Wittenberg, patients can anticipate a collaborative, patient-centered, and non-judgmental environment designed to foster a meaningful therapeutic relationship. He will thoroughly discuss individual concerns and treatment goals, exploring potential therapeutic interventions, including medication management and holistic strategies to support mental health and overall wellness.

   

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.

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Specialties
Medication Management
States
California
Arizona
New York
Languages
English