Civil rights leader Rev. Jesse Jackson announced Friday that he has been diagnosed with Parkinson’s disease.

Jackson made the announcement in a letter to supporters that he had been diagnosed with the neurodegenerative disorder that results from loss of cells in various parts of the brain that control movement. The disease also afflicted his father.

“After a battery of tests, my physicians identified the issue as Parkinson’s disease, a disease that bested my father,” Jackson writes.

“Recognition of the effects of this disease on me has been painful, and I have been slow to grasp the gravity of it. For me, a Parkinson's diagnosis is not a stop sign but rather a signal that I must make lifestyle changes and dedicate myself to physical therapy in hopes of slowing the disease’s progression,” Jackson added.

Jackson was diagnosed with the disease in 2015 and has been undergoing outpatient care, according to a statement from Northwestern Medicine provided by an aide to Jackson. Jackson said that he and family members noticed something was amiss with his health about three years ago. The disease has no cure and causes tremors, stiffness and difficulty balancing and walking.

"Now in the latter years of my life, at 76 years old, I find it increasingly difficult to perform routine tasks, and getting around is more of a challenge. My family and I began to notice changes about three years ago," Jackson writes. "For a while, I resisted interrupting my work to visit a doctor. But as my daily physical struggles intensified I could no longer ignore the symptoms, so I acquiesced."

Jackson emerged as a prominent voice in the civil rights movement in 1960s. Rev. Martin Luther King Jr. gave Jackson a role in the Southern Christian Leadership Conference and charged him with establishing a presence for the organization in Chicago.

The ordained minister would go on to twice run for the Democratic presidential nomination (1984 and 1988) and also organized the civil rights organizations Operation PUSH and the Rainbow Coalition.

He also has served as an envoy to U.S. presidents, negotiating the release of a Navy pilot with Syrian president Hafez al-Assad and persuading Saddam Hussein to release several British and American citizens who were being held as "human shields" ahead of the 1991 Persian Gulf War. He received the Presidential Medal of Freedom from President Bill Clinton.

In recent years, he's been outspoken about police brutality in black and Latino communities. He's also pushed Silicon Valley executives to diversify their workforce.