Where the experts come to work

For nearly four decades, CenExel ACMR has been dedicated to assisting pharmaceutical companies find new cures to help patients better manage their healthcare.

Center Leadership

Dr. Robert Riesenberg

Robert Riesenberg, MD

ACMR Founder and Principal Investigator

Dr. Riesenberg is a research psychiatrist with four decades of experience. His primary focus is on CNS, PK, Healthy Normal, and Child/Adolescent disorders. Dr. Riesenberg has been the Principal Investigator in over 600 studies.

Dr. Riesenberg earned a bachelor’s degree in both Zoology and Psychology from Memphis State University in 1972. In 1975, he earned his MD from the University of Tennessee. He is licensed to practice in Georgia.

Meet Our Physicians / Investigators


Maria Johnson, MD

Principal Investigator

Dr. Johnson is certified by the American Board of Psychiatry and Neurology, which means she has demonstrated knowledge, competency, and specialized skills in the treatment of psychiatric disorders. Since she began practicing in 2007, she has encountered a wide range of patients, settings, and situations. These experiences, combined with motivation to help those who suffer and excitement about new developments in the understanding of the human brain, have led to a very well-rounded set of skills.

She is a graduate of of Oglethorpe University in Atlanta, obtained her medical degree from the Medical College of Georgia, and trained in Psychiatry at The University of Arizona. She completed a fellowship in Psychopharmacology Research and completed residency at The Medical College of Georgia. She is experienced in outpatient, inpatient, public, private, child, adult, and geriatric psychiatry.

She has special interest in Autism Spectrum Disorders and edited a book called Asperger’s Disorder published in 2008. More recently, she has focused on Telepsychiatry, developing skills in the management of the technology required for Telepsychiatry, as well as the medium’s impact on her relationship with her patients.

Jessica McCoun, MD

Jessica C McCoun, MD

Principal Investigator

Dr. McCoun is board certified by the American Board of Anesthesiology. Dr. McCoun completed her residency at the University of Florida in 2011. She has training in both single injection as well as continuous catheters.

Safety and quality are paramount

Our physicians have extensive backgrounds in their respective medical specialties and always prioritize patient safety.




200+ years of collective clinical trial experience


Assisted by expertly-trained medical staff

Research Facility

Converted Hospital

With existing healthcare facility infrastructure and redesigned specifically for clinical research, CenExel ACMR offers a unique, world-class experience.


100,000 square feet of dedicated medical research space


On-site PBMC lab


14 inpatient units


2,000 square foot cafeteria with licensed dietician


Conveniently located near Atlanta’s Hartsfield-Jackson international airport and within walking distance of public transportation


CenExel ACMR

501 Fairburn Road SW
Atlanta, GA 30331

Monday – Friday    8AM – 4:30PM

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We’re a CenExel
Center of Excellence

Centers of Excellence provide unparalleled attention to detail to assure consistent and first-class quality in patient care. We have supported tens of thousands of studies, the variety and complexity of which have resulted in a great depth of experience for the principal investigators and research staff at each Center.

We deliver engagement, expertise, and results.


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