Oksana Kershtyn, MD

Medical Director

Dr. Oksana Kershteyn joined the Talbott Recovery staff in early 2012, where she serves as staff psychiatrist at Talbott Dunwoody. Since July 2018, she also fills the role of medical director at Foundations Roswell. Originally from Siberia, Russia, she graduated from Russia’s top medical school, the Siberian State Medical University, where she also completed her general adult neurology residency.
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After moving to the United States, Dr. Kershteyn completed her general adult psychiatry residency at Albany Medical College in New York. While there, she was a Chief Resident and was also awarded the Alan D. Miller Leadership Award through the New York State branch of the American Psychiatric Association. After completing her residency, Dr. Kershteyn continued to serve at Albany Medical College as consultation liaison-psychiatry, attending psychiatrist-inpatient services and attending psychiatrist-crisis services. She also served as assistant professor in psychiatry at Albany Medical College’s Department of Psychiatry. Dr. Kershtyn’s certifications include the American Board of Psychiatry and Neurology (Psychiatry) and she is a board-certified addictionologist.

Jeanne Ryan, LCSW, LSCSW

Clinical Director
Jeanne Ryan
Born and raised in Williamsville, New York, Jeanne Ryan first became a primary therapist at Foundations Atlanta at Roswell in September 2016. She chose the mental health field after a lifelong dream to work in a helping profession. Using a holistic approach, Ryan highly values the recovery journey and its importance to patients and their families.
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She earned a bachelor’s degree in psychology from Binghamton University and a master’s degree in social work from the University of Illinois at Chicago. With a background in working with youth and their families, Ryan brings a depth of experience to her role as clinical director in the Roswell community. When she’s not working, she enjoys spending time with her family, playing tennis, walking the dog, watching her kids play soccer, traveling and jewelry-making. She and her husband have a son, a daughter and a dog.

Lauren DeRossette, LPC, NCC

Primary Therapist
Lauren DeRossette
From Fort Thomas, Kentucky, Lauren DeRossette became a primary therapist at Foundations Atlanta at Roswell in 2013. Passionate about meeting people from all walks of life, it has always been her dream to work in the mental health field. DeRossette has a master’s degree in community counseling from Argosy University. When she’s not working, she enjoys writing, yoga, soccer, dancing and music. DeRossette has two cats, Romeo and Felix, and has been with her partner for several years.

Theresa Westfall

Primary Therapist
Theresa Westfall
Theresa Westfall has been a primary therapist with Foundations Roswell since December 2017. She holds a degree in psychology from Emory University and a Master of Science in clinical mental health counseling from Mercer University. She is specially trained to administer trauma treatment, including the use of progressive counting and brainspotting. She is also trained in collaborative and proactive solutions – a model used to build strong communication and address behavioral challenges.
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After university, Westfall completed her clinical internship at New Life Community Ministries in Decatur, Georgia, where she assisted in developing their counseling and case management program.

Westfall was born in Charlotte, North Carolina, but raised in Decatur, Georgia. From an early age, she knew she wanted to become a therapist and help others. She loves seeing people gain self-esteem, find healing and change the trajectory of their entire lives through therapy. “I love that the work is so dynamic,” she said. “I am continually learning and growing as a counselor.” When she isn’t working, she enjoys spending time with her husband and two kids, camping, reading, practicing photography and painting.

Mitzi Hargett, RN

Director of Atlanta Outpatient Nursing Services
From North Alabama, Mitzi Hargett joined the Foundations Atlanta team in November 2010. Director of outpatient services for both Roswell and Midtown locations, she is passionate about carrying the message of recovery with compassion. Hargett earned her associate’s degree in nursing from South Dakota State University. When she’s not working, she loves reading, shopping and spending time with her son.

Christy Crane

Business Office Manager

Carla Matias

Assessment Manager