Meet Our Clinical Staff


Shannon D. Mullen, Ph.D., CSAT

Shannon D. Mullen completed her Ph.D. in Counseling Psychology from The University of Tennessee in Knoxville, Tennessee, in 2008. She is a licensed psychologist in the states of Georgia and Florida and a PSYPACT clinician. Before her doctoral studies, Dr. Mullen completed a Master of Arts in Counseling at the University of New Orleans. Dr. Mullen established Mosaic Psychological Services in 2010, where she provides clinical and forensic services. Clinical areas of specialty include trauma, attachment, sexual health/addictions, and psychological evaluation. Additionally, as a Certified Sexual Addiction Therapist, she provides targeted interventions for individuals struggling with sexual infidelity and addiction to sexual material and behaviors. Patients are guided through the recovery process through specialized interventions to initiate and sustain long-term recovery and restore relationships broken by betrayal trauma. Dr. Mullen has nearly 20 years of treatment and assessment experience in sexual disorders and addiction. Treating the whole person is a hallmark of her work, and she approaches each person with attention to the physical, emotional, and spiritual dimensions of their personhood. Dr. Mullen is trained in psychodynamic theory and currently practices through a trauma model utilizing Internal Family Systems. She is also EMDR trained. Finally, as a Catholic Christian, theology is a welcomed addition to this clinical work and forms the psychodynamic lens through which the whole person is restored to dignity and health. Dr. Mullen is also a regular speaker and consultant for religious organizations. She designs and hosts training seminars for clinicians in psychosexual assessment and treatment of clergy and clergy applicants. When not engaged in direct patient care and training, Dr. Mullen enjoys supervising emerging new mental health professionals. Georgia License PSY003406 & Florida License PY10361

Mandy B. Mullen, MSW, LCSW, CPTT

Mandy B. Mullen is a Licensed Clinical Social Worker in both Georgia and Florida. Ms. Mullen received a B.S. in Human Services and has a Masters of Social Work from Florida Gulf Coast University in Fort Myers, Florida. Her current professional specialties are play therapy, trauma counseling, child and adolescent behavioral problems as well as marital therapy and relationship counseling. Ms. Mullen is a Certified Partner Trauma Therapist (CPTT) working with the partners of sex addicts and their experience of betrayal trauma. She is certified in Trauma-Focused Cognitive Behavioral Therapy (TF-CBT) and E.M.D.R. Ms. Mullen is also the System of Care Director and is responsible for ensuring the best patient experience for receiving services at Mosaic. Georgia License CSW004523 Florida License SW10187 & Alabama 5030C

David Valpuesta, LMFT

David Valpuesta received his Master's of Science in Marriage and Family Therapy from Valdosta State University. Prior to obtaining his Master's degree, Mr. Valpuesta received his Bachelor of Science in Psychology from Florida State University. As a Marriage and Family Therapist, he understands that when people experience trauma or severe stressors, life may seem to unravel. It is his passion to help couples, families, and individuals experiencing martial or relational conflicts, adolescent behavioral problems, and bereavement issues. He is certified in Anger Management and currently certified as a level 1 in TEAM- CBT. Georgia License MFT001440

Rachelle H. Cantin, Ph.D., NCSP

Rachelle Cantin, Ph.D. is a licensed psychologist in the state of Georgia and a Nationally Certified School Psychologist (NCSP). Dr. Cantin obtained her undergraduate degree at Albion College, where she graduated with honors. Dr. Cantin received her Ph.D. in School Psychology from Illinois State University. While at Illinois State, Dr. Cantin was bestowed the Ora Bretall Graduate Fellowship and University Fellowship. She concluded her doctoral studies with a clinical internship at the APA-approved Florida State University Multidisciplinary Center (FSU MDC). Dr. Cantin has completed specialized training in autism spectrum disorder (ASD), anxiety, trauma, and neuropsychological assessment. She has extensive experience in the evaluation and treatment of developmental, educational, and behavioral disorders among child and adolescent populations. Dr. Cantin holds additional certifications as both a Certified Clinical Telemental Health Provider (CTMH) and a Certified Clinical Anxiety Treatment Professional (CCATP). Georgia License PSY003823 & Florida License PY10943

Carrie Milhous, LPC

Carrie Milhous believes that psychotherapy is a process of healing and of discovery that leads to an awareness of who you are and who you were created to be. Her clinical experiences include working with adolescents and adults who live with ADHD, anxiety, or affective disorders, assisting parents in developing successful parenting strategies, marriage preparation, and enhancement, and supporting older adults as they encounter disabilities and caregiving responsibilities. Carrie favors a strength-based approach with a cognitive-behavioral orientation and she is also a trauma-informed therapist who is an EMDRIA approved EMDR therapist. Carrie is a Licensed Professional Counselor in the State of Georgia. She obtained her Master of Arts degree in Counseling at the University of Notre Dame, and a Certificate of Advanced Graduate Studies in Clinical and Community Counseling from Johns Hopkins University. Prior to that, she received her Bachelors of Science in Psychology at Georgia Southern University. Georgia License LPC005462

Megan A. Nichols, Ph.D.

Dr. Nichols is a licensed psychologist in the states of Florida and Georgia. She specializes in the assessment and treatment of children and adolescents, with a particular interest in Autism Spectrum Disorder. She completed her doctoral studies at Florida State University where she received extensive training in assessment, consultation, and intervention across clinic, hospital, school, and university settings. Dr. Nichols earned her B.S. in psychology from the University of Central Florida and was also licensed as a general education and special education teacher in the state of Florida, where she had experience teaching students with Autism Spectrum Disorder in the general education, self-contained, and residential settings. Dr. Nichols joined Mosaic Psychological Services following the completion of an APA-accredited Predoctoral Internship and Postdoctoral residency at the Florida State University Multidisciplinary Evaluation and Consulting Center. Her training primarily emphasized the neurodevelopmental assessment of Autism Spectrum Disorder, attention disorders, internalizing concerns, and learning disorders. She also has experience providing consultation, positive behavior support, and mental health services to students in rural school districts, and parent training. Her professional interests include social skills training, improving social-emotional health, and understanding the effects of technology use on children and adolescents. Georgia License PSY004455 & Florida License PY10693

Alan Stewart, Ph.D.

Dr. Alan Stewart is a post-doctoral counseling psychologist. After a naval career that included service in combat, he completed his Masters and Specialist degrees in counseling, and his Ph.D. at Georgia State University with a dissertation examining often-unrecognized patterns of depression among African American and European American men.
Dr. Stewart’s clinical specializations include group and individual work with boys and men, assessment, and trauma. He teaches Mental Health First Aid to first responders and others, stress management to newly arrived refugees, and he is a trained Safe Outlet for LGBTQ students. He speaks publicly and teaches workshops for those working with men and boys, including The Boy Code, a keynote at the annual meeting of the Georgia Parent-Teacher Association; Ethical Competencies in the Treatment of Boys and Men, a co-led workshop for the Georgia Department of Juvenile Justice and other organizations; and Brotherhood & Leadership, an invited presentation to the Greek Student Leadership & Development Conference. He is past president of the Georgia Chapters of Boys to Men Mentoring and the ManKind Project.

Maritza Miller, Ph.D.

Maritza Miller is joining Mosaic Psychological Services for her Postdoctoral residency following the completion of an APA-accredited Predoctoral Internship at the Florida State University Multidisciplinary Evaluation and Consulting Center. She completed her doctoral studies at Florida State University where she received extensive training in assessment, consultation, and intervention across clinics, schools, and university settings. Maritza received her Master of Arts in Forensic Psychology from George Washington University. Prior to obtaining her master's degree, Dr. Miller received her Bachelor of Arts in Psychology from Dartmouth.

Taryn Wade, M.S. / Ed.S.

Taryn Wade is completing her doctoral studies in special education at Florida State University. She is a nationally certified school psychologist (NCSP) and is completing licensure hours to become a licensed school psychologist in the state of Florida. Taryn is a board-certified behavior analyst (BCBA). She earned her B.A. in psychology from the University of South Carolina and her M.S./Ed.S in school psychology at Florida State University. She has experience in assessment and intervention support with toddlers through post-high school populations.