William Walsh is a scientist with over 30 years of research experience. After graduating from the University of Notre Dame, he earned a masters degree at the University of Michigan and a Doctorate in Chemical Engineering from Iowa State University. Dr. Walsh’s research and volunteer work involving biochemical predisposition to behavior disorders led to the foundation of the Health Research Institute and the Pfeiffer Treatment Center.  

John Crayton, M.D.

Dr. Crayton is Professor of Psychiatry, Loyola University Medical School and founding Chief of the Section on Biological Psychiatry at Hines VA Hospital. He received his M.D. degree from the The University of Rochester. He was a Research Associate at the National Institutes of Mental Health, Laboratory of Neuropharmacology for three years, and then completed his residency in psychiatry at The University of Chicago. He has participated in fellowship experiences in Clinical Neurophysiology (Uppsala University, Sweden; The Mayo Clinic, Rochester, Minn; Harvard University; and Columbia University). He is board certified in Psychiatry and Clinical Neurophysiology.


Pfeiffer Treatment Center

Suzanne Speckman R.Ph Executive Director

Suzanne earned her degree in Pharmacy from Creighton University. She spent 18 years in retail pharmacy management. Suzanne was hired by HRI in March of 2004 as Pharmacy Director and was moved to Managing Director of HRI in October. Her responsibilities included management of Pfeiffer Treatment Center, HRI Pharmacy, and HRI research program. In January of 2005, Suzanne was promoted to Executive Director of Pfeiffer Treatment Center/HRI.

Allen T. Lewis, M.D., Medical Director

Dr. Lewis comes to Pfeiffer after ten years of general pediatrics practice in Utah and Montana. He received his Doctorate of Medicine from the University of Washington and completed his Pediatric Residency at Primary Children’s Medical Center in Salt Lake City. He served on the Department of Pediatrics Residency Education Committee at the University of Utah and has been a clinical preceptor for both Pediatric and Family Practice resident physicians since starting clinical practice.

Robert deVito, M.D.

After 36 years as a clinician, teacher, administrator, and leader in the field of psychiatry, Dr. deVito concluded his career as Chairman of the Dept. of Psychiatry of the Loyola University Stritch School of Medicine and Chief of Psychiatry at the Loyola University Medical Center to act as part-time Senior Consulting Psychiatrist at the Pfeiffer Treatment Center. Although he has retired from direct patient care, Dr. deVito continues clinical practice as a valuable resource to the medical and research staff.

Dawn Boyd, CNP

Dawn graduated in 1999 from the University of Illinois in Chicago with a Bachelor’s of Science Degree in Nursing. She began her career working at the Rush University Medical Center in 2000. Dawn’s choice was to work on the child and adolescent unit there. In 2004 she graduated from Rush University with a Masters of Science in Nursing. In 2005 she received her certification as a Family Psychiatric -Mental Health Nurse Practioner before coming to Pfeiffer in July of 2005.

Terri McCreedy, APN/CNP

Terri became a certified licensed Nurse Practitioner in Illinois after completing her Masters Degree in Nursing/Nurse Practitioner at North Park University. Prior to completing her Master’s Degree, she worked for ten years as a registered nurse/coronary ICU nurse. She has a B.A. in Biochemistry and has worked as a nutritionist in California.

Tracy Ziemann, P.A. -C

Tracy graduated from the Masters program for Physician Assistant Studies at Finch University/The Chicago Medical School. There she studied many different areas of medicine, with a special interest in pediatrics and adolescent medicine. Tracy received her B.A. in psychology from the University of Iowa.

Catherine Gavin, RD, LDN, MPH

Cathy has recently transitioned to Staff Dietitian. Cathy joined the Pfeiffer Staff in 1997 and worked as the Insurance Support patient advocate. She earned a Bachelor of Science in Nutrition in 2002 from Benedictine University, and completed a 2-year Dietetic Internship and Master of Public Health Degree in 2005. Cathy has a special interest in women and children’s health and nutrition, and environmental health issues. As dietitian, Cathy helps design quality diets and assists patients and families with the transition to special diets.