Taylor Cortez, LPC

Dr. David Guggenheim is an experienced clinical psychologist and health care administrator. He has worked with patients at different stages of life, including children, adolescents, and adults, and he has treated patients living with a wide range of mental health conditions, including anxiety, depression, post-traumatic stress disorder (PTSD), substance use, and attention-deficit hyperactivity disorder. Dr. Guggenheim has specific training in Trauma-Focused Cognitive Behavioral Therapy, Motivational Interviewing, and foundational training in dialectical behavioral therapy. Prior to joining Talkiatry, Dr. Guggenheim served as the Chief Behavioral Health Officer at Callen-Lorde Community Health Center in New York City, specializing in LGBTQ+ health care. In that role, he oversaw teams of providers including psychiatrists, psychologists, and social workers, who collectively provided care to thousands of patients in the New York metropolitan area. While at Callen-Lorde, he also served as co-chair for the behavioral health subcommittee of the Community Health Center Association of New York State; worked as an Adjunct Professor at Post University; and performed volunteer clinical work at the Weill Cornell Center for Human Rights. Before joining Callen-Lorde, Dr. Guggenheim worked as Associate Chief Behavioral Health Officer at Community Health Center, Inc., a federally qualified health center in Connecticut. A recognized expert, Dr. Guggenheim has delivered lectures to audiences ranging from medical schools to corporate executives, and he has been quoted in national media including The Advocate, Yahoo Finance, and Teen Vogue. Dr. Guggenheim has also been honored with an Early Career Achievement Award from the American Psychological Association in 2016. Dr. Guggenheim received his Bachelor of Arts from the University of Connecticut in 2002 and his Doctor of Psychology in Clinical Psychology from the American School of Professional Psychology at Argosy University/Washington, DC in 2009.

Chad McDaniel, LPC-MHSP, is an experienced mental health professional with a background in both outpatient and inpatient settings. He has worked extensively with clients navigating mental health and substance use challenges. Chad earned his master’s degree in counseling from Southern Adventist University and completed his clinical internship at Parkridge Valley Psychiatric Hospital, where he developed a strong foundation in evidence-based care and client-centered practice.

Chad values open communication and collaboration in every therapeutic relationship. He works alongside clients to establish clear treatment goals and realistic expectations, ensuring that care is both purposeful and personalized. His approach is grounded in empathy and respect, creating a safe and supportive environment where clients feel accepted, heard, and empowered to make meaningful change.

In the initial session, Chad takes time to thoroughly understand each client’s personal history, current concerns, and long-term goals. He then develops an individualized treatment plan that reflects their unique needs and aspirations. Throughout the therapeutic process, Chad regularly reassesses progress, adjusting interventions as needed to help clients achieve lasting growth and improved well-being.

Diamond Junior received her bachelor’s degree in arts & psychology 2007 & two master’s degrees in science, one in Community Mental Health Counseling and the second one in School Counseling Education, in 2011 and 2018. Diamond Junior now has her License in Mental Health Counseling, her Credentialed Alcoholic & Substance Abuse Counseling Certification-Trainee, and her Permanent Certification in School Counseling. Diamond is also currently in doctoral school for her School Psychology degree. Diamond is a former Alcohol and Substance Abuse Preventive Worker & Treatment and Therapeutic Foster Care Family Specialist. Diamond is now currently, an on-line therapist and has her own Mental Health Counseling Private Practice in Buffalo. Diamond's treatment styles & modalities include Trauma-Informed Therapy, Cognitive-Behavioral Therapy, and Grief Therapy.

When working with Diamond, a new patient should know that she is very down to earth and professionally direct. Diamond practices individualism and treat each patient as their own person. Diamond develops treatment plans with the patient, that tailors to each of their individual needs. Diamond is also the co-founder of an All-girls mentoring & educational program called, "Unique Sisters. Unique Sister was started in 2014 and is owned by my mother, Rhodesia Jackson.

Diamond's typical process when working with patients is to first establish a therapeutic rapport by asking open-ended questions. Diamond asks questions such as, "Have you been in therapy before, including as a  child or teen (if the patient is over 18)"? This helps Diamond starting point to build a trusting & individualized relationship with the patient. Diamond's next question would be, "Why did you first enter therapy & we're you diagnosed with any mental health disorders"? Diamond continues to go on and ask if the client is or has been on psychotropic medications and what brings them back to therapy. Diamond gathers all of this information during the first two session and then ask the patient if any skills were built during their therapy journey & if they still utilize the skills. Finally, Diamond would administer the ACE Questionnaire to assess for childhood trauma, if the patient is over 18 years of age.

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Jan Hollis-Cole, LCSW, began her career as a social worker for hospice in 1999 and has extensive experience helping families cope with death and grief due to illness and/or trauma. Following her foundational work with hospice care, Jan expanded her clinical knowledge and expertise in a variety of settings to include substance abuse, challenges related to ADHD, anxiety, depression, LGBTQIA+ issues, and navigating the foster care/adoption system.

Jan believes that connection is the foundation of positive growth and dedicates her work to providing a safe place for clients to engage in self-expression and to explore the particular challenges they face on a daily basis.

Her approach is client centered, focusing on evidenced based therapies such as Cognitive Behavioral Therapy (CBT), Dialectical Behavorial Therapy (DBT) and Eye Movement Desensitization Reprocessing (EMDR). Jan works with clients of all ages and encourages inclusion and diversity within families to promote individual growth.

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Sheena Mammen is a Licensed Clinical Social Worker with seven years of experience in various aspects of mental health. She earned her undergraduate degree from Nyack College and her Master's from Stony Brook, which deepened her understanding of the field. She specializes in treating clients with anxiety, depression, ADHD, interpersonal issues, and perfectionism. Sheena employs culturally sensitive and person-centered approaches to tailor treatments for each individual. Her eclectic therapeutic style is rooted in Cognitive Behavioral Therapy, Dialectical Behavioral Therapy, and Attachment Therapy. She also incorporates communication skills, mindfulness, executive functioning, and social skills training into her sessions, fostering comprehensive support for her clients.

Matthew Green is a Licensed Mental Health Counselor in the state of New York with over seven years of experience in outpatient settings, both in person and virtual. He earned his master’s degree from St. Bonaventure University and began his career at Olean Counseling Center, where he also completed his internship. Licensed since 2022, Matthew brings compassion and clinical expertise to each session.

Matthew strives to create a warm, supportive, and open space where clients feel safe, heard, and respected. He believes trust is essential to meaningful therapeutic work and values open communication to set clear, collaborative goals. His approach is grounded in mutual respect and genuine connection.

In the first session, Matthew gathers a thorough history to understand the full scope of a client’s experiences and goals. He then creates an individualized treatment plan and focuses initially on coping strategies to support day-to-day functioning. As therapy progresses, the work shifts toward deeper issues and goal achievement.

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