Book a therapist or psychiatrist in West Islip, NY covered by Aetna

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 worry about what tomorrow holds? Overthinking about events from the past? If you want to learn to experience the present moment, you have come to the right page. My name is Danielle and I specialize in Anxiety, Depression, and PTSD. In addition to those specialties, I support clients through a wide range of challenges including stress management, life-transitions, and self-esteem issues. I strive to create a relaxed, authentic, non-judgmental therapy environment; So, don’t be surprised if you are welcomed by a woman in jeans and sneakers. I believe the goal in therapy is for each individual to reach their highest potential.

I have a particular passion for working with men, especially guys in their 20s and 30s. A lot of the young men I see are dealing with something the research is only now catching up to — an erosion of in-person connection, a sense of drift, and a shortage of spaces where they can actually say what's going on. I'm genuinely excited and motivated by this work because I believe this generation of men needs — and deserves — real support. That said, I also welcome clients navigating anxiety, discouragement, depression, workplace stress, relationship dynamics, and life transitions of all kinds.

I'm a Brooklyn-bred Psychotherapist and earned my LCSW in 2009. I previously worked in the corporate world, and understand pressure, ambition, career transitions, and what it feels like when the thing you've built your identity around stops fitting. Since becoming a therapist, I've worked in hospitals, outpatient clinics, substance abuse treatment, and psych rehab before settling into a private practice where I'm focused on the work I care most about.

I aim to create a safe, non-judgmental space for self-exploration, discovery, and healing. By utilizing unconditional positive acceptance, my goal is to help clients add to their social and emotional knowledge so they can navigate through difficulties in ways that foster self-esteem, well-being, and growth.

What if improving your relationships isn’t starting together, but starting with you? As a Marriage and Family Therapist (LMFT), I work with individuals who are curious about their relationship patterns and ready to create meaningful change from the inside out. You may feel stuck in recurring dynamics, find yourself questioning how your family background shapes your relationships, or want to communicate more effectively. Together, we create a space to gain clarity, better understand what’s driving these patterns, and begin making intentional shifts toward healthier, more balanced relationships.