Linda B. Welsh, Ed.D.Director

Dr. Welsh is one of the founding partners of AATC over 30 years ago. She specializes in treating agoraphobia and anxiety disorders. She is trained in Cognitive Behavioral Therapy as well as psycho-dynamic therapy, EMDR, Erisksonian Hypnosis, Post Traumatic Stress Disorder, and grief counseling. Dr. Welsh utilizes a combination of treatment approaches to customize therapy for maximum effectiveness. She also lectures at local hospitals, medical schools, and community facilities highlighting stress management and communication skills. Dr. Welsh is the author of “Chronic Illness and the Family: A Guide to Living Every Day” which addresses the emotional impact of illness on the patient and family. The majority of new adult clients are evaluated by Dr. Welsh in order to match the individual with the appropriate therapist.

Gerald T. O’Brien, Ph.D.Associate Director

Dr. O’Brien is a licensed psychologist with more than 35 years of clinical experience. Dr. O’Brien specializes in the cognitive-behavioral treatment of anxiety disorders, depression, stress and worry management, and life changes. He earned his Master’ and Doctorate degrees in clinical psychology from the University of Iowa. Dr. O’Brien has taught at the State University of New York at Albany and was Assistant Director of the Anxiety Disorders Clinic at that university. He worked for more than 20 years in community mental health at the Penn Foundation in Sellersville, PA. Dr. O’Brien has been affiliated with AATC for over 20 years.

Find Dr. O'Brien on Twitter

Lori J. Kasmen, Psy.D. Director of the Program for Children and Adolescents

As Director of Child and Adolescent Services at AATC, Dr. Kasmen specializes in providing cutting-edge, empirically-supported Cognitive-Behavioral therapy (CBT) and Exposure/Response Prevention (E/RP) to children (ages 4+), teens, families and adults affected by anxiety, OCD and related concerns. An expert in the field with over 18 years of experience, she has written numerous articles and presents regularly to consumers and professionals on anxiety and related topics. She also trains psychologists and other professionals in the use of CBT. In addition to her work at AATC, Dr. Kasmen serves as the Anxiety Consultant to the School District of Haverford Township.

Dr. Kasmen is a graduate of Emory University where she was elected Phi Beta Kappa. She received her master’s and doctoral degrees from the Georgia School of Professional Psychology. She completed a pre-doctoral internship at duPont Hospital for Children (Nemours). She was awarded a grant by the Nemours foundation to further her training through completion of a three-year post-doctoral fellowship at duPont, with a focus in cognitive-behavioral therapy, neuropsychological evaluation, and psychological treatment of children with medical illnesses.

Dr. Kasmen has extensive experience treating the full range of anxiety disorders across the age span, including severe/complicated OCD (and PANS/PANDAS), Generalized Anxiety Disorder, adjustment disorders, panic disorder, separation anxiety, shyness/social anxiety, stress management, and specific phobias. Dr. Kasmen also treats ADHD, Autism Spectrum Disorders, behavioral issues, school avoidance, sleep problems, tics, and body-focused repetitive disorders (e.g., compulsive hairpulling/skinpicking). In addition to individual treatment, she enjoys working with parents and families around these concerns. Dr. Kasmen is a professional member of the International OCD Foundation and the Pennsylvania Psychological Association.

Leslie G. Lenox, L.C.S.W., DCSW

Leslie is a psychotherapist with more than 30 years of clinical experience. She specializes in agoraphobia, anxiety and panic disorder, couples therapy, and women’s issues. She treats adults, adolescents, and students with adjustment and developmental issues. Formerly, she was a Clinical Associate Professor at Temple University Medical School, where she supervised medical students and psychiatric residents.

Chelsea H. Hersperger, Psy. D.

Dr. Hersperger earned her doctorate in clinical psychology at the Graduate School of Applied and Professional Psychology of Rutgers, the State University of New Jersey. While at Rutgers, she received training in the treatment of obsessive-compulsive spectrum disorders, using cognitive-behavioral therapy, exposure and response prevention, and habit reversal training. Dr. Hersperger completed her pre-doctoral internship at Terry Children’s Center in New Castle, DE, where she was trained in trauma-focused cognitive behavioral therapy as well as parent-child interaction therapy. She specializes in the treatment of anxiety and related disorders in children, teens and adults

Danielle D.Trucksess Ph.D.

Danielle Trucksess received her Ph.D. in Clinical and Developmental Psychology from Bryn Mawr College. She specializes in the treatment of anxiety and related disorders in children, adolescents, and adults. In addition to her clinical internship and post-doctorate training at University Counseling Centers working with young adults, Dr. Trucksess received specialized training in exposure-based treatments for anxiety disorders at the University of Pennsylvania’s Center for the Treatment and Study of Anxiety (CTSA). She is also a certified school psychologist and has worked at the Upper Darby School District, The Philadelphia School, and the Child Study Institute at Bryn Mawr College in that capacity.

Niela M. Hirsch, Psy.D.

Dr. Hirsch specializes in cognitive-behavioral and exposure-based therapies for children, adolescents, and adults. She also currently co-leads the children and adolescent CBT groups with Dr. Lori Kasmen. Dr. Hirsch received her doctorate in Clinical Psychology from La Salle University, where she completed her doctoral dissertation on the development of a prenatal distress measure that is currently in publication. Her pre-doctoral internship was conducted at the Wilmington Veteran Affairs Medical Center, where she received training in trauma therapies and mindfulness based approaches. In addition to her work in private practice, Dr. Hirsch has served as a therapist at college counseling centers and community mental health clinics, and as an adjunct professor at Temple University.

Mark Ferreira, Psy.D.

Dr. Ferreira has 14 years of clinical experience working with children, teens, adults, and families within a cognitive behavioral framework. He received his doctoral degree from the Graduate School of Applied and Professional Psychology of Rutgers University, while his pre-doctoral internship was conducted at Rutgers University Medical School. Once his doctoral training was completed Dr. Ferreira completed a two-year postdoctoral fellowship at the University of Pennsylvania, Child & Adolescent OCD, Tich, Trich, & Anxiety Group (COTTAGe). Here he received specialized training in Cognitive Behavioral Therapy for Anxiety Spectrum Disorders, including but not limited to Obsessive Compulsive Disorder (OCD), Generalized Anxiety Disorder, and Social Anxiety Disorder. Dr. Ferreira also specializes in utilizing Habit Reversal Training (HRT) in the treatment of Tourette's Syndrome and related tic disorders, Trichotillomania (hair pulling), and skin picking (excoriation).

Daniel Chazin, Ph.D.

Dr. Chazin is a licensed psychologist specializing in cognitive-behavioral treatments for anxiety, obsessive-compulsive, and depressive disorders in adults, adolescents, and children. He combines expert training in effective treatment strategies with a personalized, client-centered approach to help clients gain mastery of a variety of problem areas, including many complex and difficult-to-treat areas.

Dr. Chazin's specialties include OCD and related disorders (such as body dysmorphic disorder and compulsive hair pulling); PTSD and trauma; panic attacks; social anxiety; health anxiety; generalized anxiety and worry; perfectionism; specific anxieties (such as driving and flying); depression; borderline personality disorder; and problems of emotional dysregulation. He is an expert in Cognitive-Behavioral Therapies (CBT), Exposure and Response Prevention (ERP), Prolonged Exposure (PE), Cognitive Processing Therapy (CPT), Dialectical Behavior Therapy (DBT), Habit Reversal, and Mindfulness Based Treatments.

Dr. Chazin has authored multiple publications and presentations at national and international conferences. He is an active member of the Association for Behavioral and Cognitive Therapies (ABCT) and the Anxiety and Depression Association of America (ADAA), and has taught undergraduates, graduate students, and psychiatry residents at Rutgers, University of Pennsylvania, and Saint Joseph's University. He received his bachelor’s degree from Yale University and his master's and doctoral degrees in clinical psychology from Rutgers University. Dr. Chazin completed his clinical internship at the Boston Consortium in Clinical Psychology and the National Center for PTSD Behavioral Science Division and his postdoctoral fellowship at the University of Pennsylvania’s Center for the Treatment and Study of Anxiety.

Joanne M. Kling, MBA Practice Administrator

Joanne is the Practice Administrator at AATC. She earned a Master of Business Degree from Holy Family University in Philadelphia. She serves as a mentor for the American College of Healthcare Executives. Joanne is continuing her professional development as a Fellow of ACHE where she is pursuing board certification in healthcare management (FACHE). Joanne is available to assist you with any questions you may have regarding insurance claim management.

Anna Akritidis

Anna is the Office Coordinator at AATC. She provides administrative support to our Practice Administrator and Clinical Staff.