U.S. Sen. Johnny Isakson, R-Ga., said in a statement issued Wednesday that he has Parkinson’s disease.

The 70-year-old veteran senator said he was first diagnosed in 2013 after seeing a neurologist in 2012 for stiffness in his left arm. He added that he still will run for a third Senate term in 2016.

“My diagnosis has not impacted my ability to represent the state of Georgia in the U.S. Senate,” Isakson said. “I am serving on five Senate committees and am the only Republican serving as chairman of two Senate committees. I am busier and have more responsibility today than ever before in my political career, and I couldn’t be happier about that. I remain devoted to public service, to my state and to my constituents. I am eager to take my record of results to the voters of Georgia as I run for re-election in 2016.”

Gov. Nathan Deal, a fellow Republican, quickly issued a statement in support of Georgia’s senior senator.

“In the 35 years that I’ve known Johnny Isakson, he has risen to meet — and overcome — every obstacle he’s encountered with determination and a smile on his face,” Deal said. "There’s not a doubt in my mind that he and Dianne will rise to meet this challenge. As he fights this battle, our distinguished senator will continue representing Georgians’ conservative principles in Washington."

Isakson said he is in the “early stages of the disease, and my main symptoms are the stiffness in my left arm and a slowed, shuffling gait.”

“The recovery from the back surgery I had in October 2014 also has affected my gait,” he said. “I have undergone rigorous physical therapy; I do exercises every morning and evening; and I take two Parkinson’s medicines.”

Isakson’s news release also included a statement from his treating neurologist, Dr. Thomas M. Holmes, based in Marietta.

Holmes said that based on his most recent assessment of Isakson, the senator “is in Stage 1.5 of five accepted stages of Parkinson's disease.” Holmes added that Isakson “has been dedicated to performing the physical therapy and maintaining the daily exercise routine, and he has been compliant with his medication treatment.”

“He has continued to maintain his rigorous Senate schedule without difficulty since 2012,” Holmes said. “I believe he is fully capable of continuing to perform his duties as a U.S. senator, and I believe he is fully capable of running for re-election and serving for another term.

“As a practicing neurologist,” Holmes continued, “I have treated many patients with various chronic neurological diseases, and I encourage all them to pursue their livelihoods with vigor and enthusiasm. With this in mind, I have encouraged Sen. Isakson to do the same.”

Isakson said he struggled with whether he should disclose his diagnosis. But he concluded that he wanted to be open with his constituents.

“While I am facing this health challenge head-on, I have wrestled with whether to disclose it publicly,” he said. “I recently shared the news with my three grown children and my senior staff a couple of months ago. Their support, along with the steadfast support of my wife, Dianne, helped me to take this step today. In the end, I decided I should handle my personal health challenge with the same transparency that I have championed throughout my career.”

According to “frequently asked questions” included in Isakson’s news release, Parkinson's disease is a chronic movement disorder and symptoms progress over time. More than 1 million people in the United States are living with the disease, which has no known cause or cure. Despite that, there are treatment options to help manage symptoms, including physical therapy, exercises, medication and surgery.