Karelis Sierra-Cintron, MD

Dr. John Lundeen earned his medical degree from the Medical College of Georgia and completed his psychiatry residency at TriStar Centennial Medical Center. He has worked with adults of all ages in both outpatient and inpatient settings, bringing a wide range of experience to his practice.

Dr. Lundeen approaches every patient with respect, empathy, and a genuine desire to understand their unique experience. He recognizes that seeking treatment can be intimidating and strives to create a welcoming, non-judgmental environment where patients feel safe and heard.

Dr. Lundeen believes in a collaborative treatment process, prioritizing each patient’s goals, values, and input. He emphasizes mental health education as a core component of care, empowering patients to better understand their treatment options and take an active role in their well-being.

Background and credentials

Dr. Agarwal is a board-certified adult psychiatrist. He obtained his bachelor's degree in Biological Sciences from the University of California at Irvine and graduated cum laude with his medical degree from the American University of Antigua. Dr. Agarwal completed his psychiatry residency training at the University of Central Florida, where he was elected chief resident.

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Treatment approach

Dr. Agarwal employs a collaborative and patient-centered approach, primarily focusing on medication management in combination with supportive therapy. He is a strong advocate of psychoeducation, believing it to be an integral part of effective psychiatric care. Dr. Agarwal specializes in treating adults experiencing depression, anxiety, PTSD, and insomnia. He is also experienced in managing patients with psychiatric conditions complicated by medical comorbidities such as obesity, hypertension, chronic pain, and diabetes.

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What you can expect in a first visit

Patients visiting Dr. Agarwal for the first time can anticipate a comprehensive evaluation conducted in a collaborative and supportive environment. Dr. Agarwal prioritizes understanding each patient's individual needs and concerns, creating a personalized treatment plan that integrates medication, supportive therapy, and psychoeducation. Follow-up visits typically last about 30 minutes, allowing time to adjust treatment and reinforce therapeutic strategies.

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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.

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Dr. Pallavi Tatapudy, MD, earned her medical degree from the Renaissance School of Medicine at Stony Brook University, where she was inducted into the Gold Humanism Honor Society. She completed Stony Brook’s combined residency in Adult Psychiatry and fellowship in Child and Adolescent Psychiatry, along with the Leadership Education in Neurodevelopmental Disabilities Fellowship. Board certified in adult psychiatry and board eligible in child and adolescent psychiatry, she has worked across inpatient, emergency, outpatient, and school settings. Her training includes expertise in Cognitive Behavioral Therapy, Psychodynamic Psychotherapy, and Motivational Interviewing, and she incorporates principles from Supportive Psychotherapy, Dialectical Behavior Therapy, and Family Systems Therapy.

Dr. Tatapudy’s warm, approachable style values each patient’s lived experience. She practices attunement to align with her patients and prioritizes cura personalis—care for the whole person. She is skilled in medication management for a wide age range and integrates therapeutic skill-building. Outside of work, she enjoys nature, visiting national parks, water activities, Indian Bhangra dance, music, and reflecting on meaningful quotes.

Dr. Tatapudy sets a collaborative agenda, listens attentively, and thoroughly reviews patient history. She includes perspectives from support systems when appropriate, offers psychoeducation with creative examples, and encourages open questions and feedback. She shares credible resources, supports learning together, and helps patients define realistic goals and measurable benchmarks for progress.

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. Gloria Odum is a board-certified psychiatrist who treats adult patients. She completed her undergraduate studies at Johns Hopkins University, Baltimore, MD, where she received her Bachelor's degree with Honors in Public Health, then completed her medical degree at The University of Texas at Houston. She completed her residency in psychiatry at the University of Texas Dell Medical School in Austin, where she served as chief resident. Dr. Odum has worked in several clinical, leadership and administrative positions and has been actively involved in teaching and community outreach. She previously worked at The Menninger Clinic, which specializes in psychotherapeutic treatments. Dr. Odum has expertise in treating a wide variety of mental health disorders including depression, anxiety, PTSD, trauma disorders, bipolar disorder, schizophrenia, ADHD, OCD, and addiction. Dr. Odum strongly believes in treating the person and not the diagnosis. Dr. Odum's approach is holistic, collaborative, supportive, and patient-centered. Dr. Odum has been in practice since 2011.

Dr. Mark Sundahl is a board-certified adult psychiatrist. He was born and raised in the suburbs of Kansas City, Kansas. He has always been fascinated by the natural world and received a bachelor’s degree in biology at Kansas State University where he was active in a research lab investigating protein function in the human body. He completed medical school training and residency at the University of Kansas School of Medicine in Kansas City, Kansas along with Wichita, Kansas. Dr. Sundahl has experience working with a broad range of mental health symptoms and a diverse patient population

Dr. Mark Sundahl is a board-certified adult psychiatrist. He was born and raised in the suburbs of Kansas City, Kansas. He has always been fascinated by the natural world and received a bachelor’s degree in biology at Kansas State University where he was active in a research lab investigating protein function in the human body. He completed medical school training and residency at the University of Kansas School of Medicine in Kansas City, Kansas along with Wichita, Kansas. Dr. Sundahl has experience working with a broad range of mental health symptoms and a diverse patient population

Dr. Sundahl understands the importance of collaboration and the therapeutic alliance when working with patients. He will clearly explain his findings and discuss treatment options he feels are reasonable. Dr. Sundahl thinks it is important for patients to have all the necessary information to make informed decisions when it comes to their psychiatric treatment.

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