IU Health Ball Memorial Leadership

Kreigh Cook

Chief Operating Officer and Hospital Administrator

Kreigh Cook was born and raised in Mt. Summit, Indiana. He earned a Bachelor of Arts degree from Olivet Nazarene University and later completed both a Doctor of Jurisprudence and a Master of Health Administration at Indiana University.

After graduation, Cook returned to East Central Indiana and has held various leadership roles at IU Health Ball Memorial Hospital. He currently serves as Chief Operating Officer and Hospital Administrator.

Cook is passionate about living in, contributing to, and serving the communities of East Central Indiana. Outside of work, he enjoys attending sporting events with his family and coaching youth basketball.

Chris Gamble, MD, FACP, FHM, CPE

Chief Physician Executive

Dr. Chris Gamble, an Indiana native, grew up in Anderson. He earned a bachelor’s degree in biology from Virginia Military Institute before returning to Indiana to attend the Indiana University School of Medicine. In 2008, he joined IU Health Ball Memorial Hospital, where he completed his Internal Medicine Residency.

Throughout his tenure at Ball Memorial, Dr. Gamble has held a variety of clinical and leadership roles. Prior to entering physician leadership, he practiced as a hospitalist and later served as Hospitalist Director, Director of Quality and Safety, Director of Hospital-Based Specialties and Associate Chief Medical Officer. He also serves as clinical faculty for the IU School of Medicine, teaching Foundations of Clinical Practice to first-year medical students. His current clinical focus is primarily in preoperative medicine.

Outside of his professional responsibilities, Dr. Gamble is actively involved in the community. He volunteers with several organizations and serves on the board of directors for the Muncie YMCA. He and his wife, Nichole, an ambulatory care pharmacist with IU Health, have been married for 24 years. They have two sons in college and enjoy golfing, fishing, traveling and spending time outdoors together.

Ryan Johnston, MD, FACP

Chief Medical Officer

Dr. Ryan Johnston serves as the chief medical officer for the East Region. Since 2005, Dr. Johnston has been a member of the medical staff at IU Health Ball Memorial Hospital. He has served in several leadership roles with the Internal Medicine Residency Program, Inpatient Medicine and the Hospitalists Program.

Dr. Johnston earned his medical degree from the Indiana University School of Medicine and completed his residency at Northwestern.

Eric Tharp

Chief Practice Officer, IU Health Medical Group East Region

Eric Tharp, a Muncie, Indiana native, began his career as an X-ray technologist at IU Health Methodist Hospital in Indianapolis. He later returned to Muncie to complete his degree and subsequently transitioned into leadership within the Medical Imaging department at IU Health University Hospital.

In 2013, Tharp began leading the physician group, which has since evolved into the role he holds today, overseeing the regional IU Health Medical Group.

He is committed to keeping care local for the communities he serves and is passionate about building high performing care teams that exemplify IU Health’s culture and values.