CHICAGO—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, which 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, according to a statement from Northwestern Medicine provided by an aid to Jackson.

"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. Martin Luther King Jr. gave Jackson a role in the Southern Christian Leadership Conference and was charged 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 groups Operation PUSH and the Rainbow Coalition.