Meet Our Providers Florida

Dr. Jawad Riaz, MD

Dr. Jawad Riaz completed medical training at King Edward Medical University, Pakistan. Early during medical school, he became enthusiastic about pursuing combined training in internal medicine and psychiatry. He completed his psychiatry residency at Mount Sinai School of Medicine, Cabrini Medical Center. He has often been inspired by patients’ resilience, creativity, and innovation in solving complex problems and navigating shared decisions between patients and physicians. He also has vast experience working as an adult psychiatrist at a community medical health center.

In his practice, he focuses on comprehensive and extensive psychiatric evaluations, and treatment plans specific to individual needs to promote lifestyle balance and mental well-being. Dr.Jawad Riaz has significantly earned the reputation of treating patients with all psychiatric issues ranging from depression, mood disturbances, bipolar disorder, panic, social anxiety, OCD, psychosis, Paranoia, schizophrenia, sleep problems, attention problems, PTSD, as well as troubles with work and relationships.

Currently, he is an active member of The American Psychiatry Association (APA), American Medical Association (AMA), American Association of Sleep Medicine (AASM), and American Association of Addiction Medicine (AAAM)

Dr. Jana Cua, MD

Dr. Jana Erika Cua is a board-certified psychiatrist and serves as Medical Director for three companies. She practices telepsychiatry and supervises mid-level providers.

Dr. Cua was born and raised in New Jersey. She graduated cum laude from the University of Florida with a Bachelor of Science in Biology in 2009. In 2011, and graduated with a Master of Science in Biochemistry from Rutgers University. She continued to obtain her Doctor of Medicine degree from Ross University in 2015, graduating with High Honors. She did her Internal Medicine internship from 2016-2017 at Florida State University before transferring to psychiatry. She completed an ACGME-accredited Psychiatry Residency at Community Health of South Florida and served as chief resident in her final year. Dr. Cua is working on obtaining her Master of Business Administration from the University of Miami.

Dr. Codie Vassar, MD

Dr. Codie Vassar, a dedicated psychiatrist. He is passionate about helping people and has a strong background in mathematics and science. With his expertise in psychiatry, he specializes in diagnosing, treating, and preventing mental illnesses for individuals aged six and above.

Dr. Vassar completed his undergraduate studies at the prestigious University of Wisconsin-Madison and earned his medical degree from the renowned Medical College of Wisconsin. Fluent in English and Spanish, he ensures effective communication with a diverse range of patients.

Dr. Vassar’s patient care philosophy revolves around collaboration, empowerment, and psychoeducation. He actively involves his patients in their treatment journey, encouraging shared decision-making and ensuring they have a thorough understanding of their condition and available treatment options.

Offering medication management and evidence-based psychotherapy, Dr. Vassar provides comprehensive care to promote mental health and well-being. He tailors treatment plans to each patient’s unique needs and values, embracing cultural sensitivity in his approach.

Patients can expect a warm and caring environment when visiting Dr. Vassar. His genuine concern for their well-being and commitment to their success in both health and overall quality of life create a trusting and supportive therapeutic relationship. Whatever the need may be—medication management or psychotherapy—Dr. Vassar’s expertise and genuine care will guide patients towards improved mental well-being.

Lisa Shallenberger, PA-C

Lisa Shallenberger is a physician assistant with a certificate of added qualifications in psychiatry. She has 30 years of healthcare experience. She earned her undergraduate degree at California State University at Northridge. She furthered her education by attending Miami Dade College’s physician assistant program, where she graduated with honors and is a member of Phi Theta Kappa, the honors society. She attained a master’s degree in medical science at St. Francis University, where she graduated with honors and is a member of Delta Epsilon Sigma. Having lived in Miami for over 20 years, she realized the importance of patients being understood and became conversant in Spanish.

As a member of the Orlando Psychiatric Associates family, she has found a unique opportunity to reach people in need. She has a particular interest in finding the best treatment for everyone in a positive, professional, and caring manner. Performing a thorough psychiatric evaluation and creating an individualized treatment plan is the foundation of her treatment of patients. Taking into consideration medical needs and genetic background allows for the personalization of the treatment and long-term goals. She relies on therapists and other OPA team members to create the best environment for patient success. Her areas of interest include bipolar disorders, anxiety disorders, major depression, adjustment disorders, attention deficit hyperactivity disorder, psychotic disorders, and post-traumatic stress disorder. Before finding her dream job in psychiatry, she worked in a variety of specialties, such as neurology, pain management, aesthetics, and internal medicine. Additionally, she has written for the Rosh Review, an academic and didactic review that assists students in the field of medicine to achieve their goals. These experiences have granted her a unique perspective in her patients’ best management and treatment.

Nathaniel Kalil, DNP, PMHNP-BC

Dr. Nathaniel Kalil is a board-certified Psychiatric Mental Health Nurse Practitioner who enjoys working with individuals and families across all stages of life. He earned his Doctor of Nursing Practice from Hawai‘i Pacific University, where he focused on delivering compassionate, culturally responsive mental health care.

He treats a wide range of conditions, including anxiety, depression, ADHD, trauma, and stress-related concerns. Dr. Kalil is committed to creating an inclusive and affirming environment where patients from all backgrounds feel respected, understood, and supported, including members of the LGBTQ+ community.

His approach is collaborative, practical, and patient-centered. He believes the most effective care comes from strong partnerships, and he takes the time to listen, educate, and develop personalized treatment plans aligned with each patient’s goals.

Dr. Kalil provides care in English, Portuguese, and Spanish, helping ensure accessible and effective communication for a diverse patient population.

Angela Whittamore, PMHNP

Angela Whittamore, PMHNP, is a board-certified Psychiatric-Mental Health Nurse Practitioner dedicated to providing compassionate, patient-centered psychiatric care. With a strong foundation in nursing and advanced training in psychiatric mental health, she provides comprehensive psychiatric evaluations, diagnosis, medication management, and ongoing monitoring.

Angela takes a thoughtful and patient-focused approach to understanding each patient’s symptoms, concerns, and mental health needs. She is committed to providing evidence-based care in a supportive and respectful environment, with a focus on helping patients achieve greater stability and overall well-being.

Her clinical approach emphasizes individualized care and ongoing collaboration, ensuring that each patient receives care based on their unique needs and goals.

Ariel Jakes, PMHNP

Psychiatric Mental Health Nurse Practitioner with extensive clinical experience delivering patientcentered care across medical and psychiatric settings. Skilled in comprehensive psychiatric assessment, diagnosis, psychopharmacological management, and crisis intervention across the lifespan. Experienced in telehealth psychiatry, outpatient behavioral health, and crisis stabilization services.

Brings a strong foundation in medical management and chronic disease care that enhances treatment of patients with co-occurring psychiatric and medical conditions. Known for strong clinical judgement, collaborative interdisciplinary practice, and compassionate patient advocacy in complex healthcare environments.