Find a therapist in Great Neck, NY — covered by insurance

As a clinical psychologist, I assist patients in reshaping negative thought and behavior patterns in a judgement free setting.

Hi, I'm Jean-Jeffrey Marcellus, DNP, PMHNP-BC, AGNP-BC, a board-certified Psychiatric Mental Health Nurse Practitioner with over 19 years of healthcare experience. I provide compassionate, evidence-based care for adults experiencing ADHD, anxiety, depression, insomnia, and substance use disorders.

I specialize in Medication-Assisted Treatment (MAT) for alcohol, opioid, benzodiazepine, kratom, and prescription medication dependence. My approach is collaborative and personalized, focusing on creating treatment plans that support each individual's goals, recovery, and overall well-being.

I offer both in-person and telehealth appointments, providing a welcoming, judgment-free environment where patients feel heard, respected, and empowered. I am committed to delivering culturally responsive care and making high-quality mental health services accessible to individuals from diverse backgrounds.

Do you notice patterns of behaviors that you are unsatisfied with? Therapy is a significant step towards working through and facing life's most difficult challenges. I have worked with adults, adolescents and children treating issues of adjustment, self-doubt, mood swings, trauma and anxiety attacks. When you approach the therapeutic process with curiosity, you can grow, heal, and thrive.

Does your child or adolescent’s behavior leave you wondering, “What is going on?”Are they having meltdowns, withdrawing, struggling at school, worrying, or feeling sad? Children and adolescents often communicate their feelings through behavior long before they have the words to explain what they are experiencing.I work with children, adolescents, and families navigating challenges such as adoption, divorce, co-parenting, blended-family transitions, grief and loss, school-related worries, family conflict, and the growing push for independence. I help children and caregivers better understand what may be underneath the behavior while strengthening connection, communication, and emotional regulation. I am a Licensed Clinical Social Worker (LCSW) and Registered Play Therapist-Supervisor (RPT-S). I received my Doctorate in Clinical Social Work (DSW) and Master’s in Social Work (MSW) from New York University, and my Bachelor’s of Science in Social Work (BSW) from Cornell University. With more than two decades of clinical experience across inpatient, outpatient, and residential settings.

I am a Double Board-Certified nurse practitioner specializing in psychiatric mental health and family health. As a dedicated psychiatric nurse practitioner, I use an integrative and holistic approach to mental health. As a family nurse practitioner, I take into consideration how physical health impacts mood and relationships. I employ evidence-based medication management. Together, we can pinpoint what's causing you stress and navigate towards a balanced state. I employ brief supportive psychotherapy in every session to help patients manage their emotions, particularly those dealing with chronic illnesses or experiencing high levels of stress. By offering empathy and validation, I aim to strengthen coping mechanisms, boost resilience, and enhance overall mental well-being.