After decades of fighting for justice, civil rights, and equality, the man whose friends call him “Tree’’ is now ready for a new battle.

“You have to fight it; you have to address it,’’ Charles J. Ogletree Jr. says of his recently announced diagnosis of Alzheimer’s disease.

Despite revealing that he has the disease, the Harvard Law School professor, activist, and author said Monday that he has no plans to retire or clear his busy schedule.

Instead, he feels called to spread awareness, especially among other people of color, who are disproportionately likely to develop the neurological disorder.

“I want to be a spokesperson,’’ Ogletree, 63, said by phone Monday. “I want to tell people don’t be afraid of it.’’

The disease took him by surprise, and Ogletree said he was not aware of any symptoms of the progressive form of dementia until his doctor raised the issue during a regular checkup.

“I said, ‘I’m too young for that,’ ’’ he recalled.

But fighting for what he believes in is nothing new for Ogletree.

He founded the Charles Hamilton Houston Institute for Race and Justice at Harvard Law School, and has taught law to Barack and Michelle Obama, among many others, during three decades at the law school.

In addition, his clients have included rapper Tupac Shakur and law professor Anita Hill, whom he represented when she accused Clarence Thomas of sexual harassment during Thomas’s 1991 Supreme Court confirmation hearings.

“My sense is that I have to keep moving forward,’’ Ogletree said. “Those are my favorite words.’’

Ogletree went public with his diagnosis last week during a speech at a Philadelphia conference of the African Methodist Episcopal Church. After the speech, he said, many men came up to thank him and share their stories of being diagnosed with the disease.

“ ‘I’m glad you’re so brave to talk about it,’ ’’ Ogletree said the men told him. “ ‘You’ve given me a sense of what I need to say. . . . I need to talk about my illness as a strength and a wake-up call.’ ’’

Dennis C. Sweet, an attorney in Jackson, Miss., said he formed a lifelong friendship with Ogletree when they worked together at the Public Defender Service for the District of Columbia in the early 1980s.

He said Ogletree turned down many more lucrative offers because he wanted to provide a proper defense for those who could not otherwise afford one.

“He did that because he believed that getting a law degree was for public service, not for self-wealth,’’ Sweet said. “He turned everybody down for a job paying $16,000 a year.’’

Sweet compared his friend to civil rights leader Medgar Evers, whose children Sweet knew when he was growing up in Mississippi. He said Ogletree shares Evers’s selfless desire to make the world better.

“If anybody can deal with this, he can,’’ Sweet said of Ogletree. “He’s had many a challenge in his life.’’

Ogletree is now on a regimen of medication, regular exercise, eating healthy, and drinking lots of water. And it’s important, he said, that people diagnosed with Alzheimer’s remain active and heed their doctors’ advice.

Ogletree has written, co-written, or edited books on capital punishment, police conduct in minority communities, the arrest of Harvard colleague Henry Louis Gates Jr. by Cambridge police, and the Supreme Court’s Brown v. Board of Education decision outlawing school segregation.

His education and intellectual accomplishments could be a benefit as he faces the disease, according to Susan Antkowiak, vice president of programs and services for the Massachusetts/New Hampshire chapter of the Alzheimer’s Association.

Antkowiak said highly educated people and those whose curiosity has led them to absorb a great deal of information exhibit “cognitive reserve’’ that can act as a buffer to their gradual decline.

“While deterioration is happening, there may be more to work with, compared to someone who hasn’t sought out information,’’ she said. “Cognitive reserve allows the person more . . . coping skills to manage the disease.’’

That does not necessarily mean the disease will progress more slowly, she said, and many factors, including overall health and the age of onset, affect its timeline. The average person lives six to eight years, Antkowiak said, but some survive for 10 or 20 years.

Martha L. Minow, dean of Harvard Law School, was not available for comment Monday evening. She addressed the diagnosis and its effects on Ogletree and his wife, Pamela Barnes, in an e-mail to law school faculty earlier in the day.

“I know you join me in sending strength, support, and love to Tree, Pam, and their children,’’ Minow said. “I am so glad that he will continue to speak, write, and be a vital member of our community as long as he is able.’’

Ogletree made it clear Monday that he has many future plans.

“There are things that I want to do,’’ he said. “I want to spend more time fishing, more time visiting my children and grandchildren.’’

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox.