The reports about Fidel Castro's health have swirled around for years, growing more frequent as the 79-year-old Cuban leader grows older and interest in his inevitable succession sharpens.

Sometimes he is said to have cancer. Other times, he is said to have suffered a series of small strokes.

Most recently, a U.S. official told The Associated Press in Washington Wednesday that an intelligence assessment based on a wide variety of material suggests Castro has Parkinson's disease — something rumored and laughed off by the president as long as seven years ago.

The official, who spoke on condition of anonymity because of the information's sensitivity, emphasized the assessment is based on analysis and is not a definitive conclusion.

Cuban officials have long dismissed reports that Castro has Parkinson's or any other chronic ailment. Last month, parliament speaker Ricardo Alarcon insisted "he's in excellent health" when the Cuban president didn't show at the Ibero-American summit in Spain.

On Wednesday, authorities in Havana did not immediately respond to a request for reaction to the latest reports about Castro's health, first published in The Miami Herald. The newspaper cited two unidentified U.S. government officials as saying the CIA believed Castro had Parkinson's and has warned major American policymakers to be prepared if he grows sick in the coming years.

The obsession with the Cuban leader's health is especially profound in South Florida, home to hundreds of thousands of anti-Castro exiles who dream of a different country after their nemesis dies. Castro, who turns 80 next August, has ruled the island for nearly 47 years — since the triumph of the 1959 Cuban revolution.

Castro's designated successor has long been his younger brother, 74-year-old Defense Minister Raul Castro.

Castro and other Cuban officials insist "there will be no transition" and that the island's socialist political and economic systems will live on long after he is gone.

It may never be known for certain whether or not Castro has Parkinson's disease, but in recent years he has begun to look his age.

The bushy black beard is thinner and grayer and he moves more slowly and stiffly, especially since an accidental fall last year that shattered his left kneecap and right arm. While slow movement and rigidity are common symptoms of Parkinson's, they are also common to aging.

After Hurricane Wilma flooded a long stretch of coastal Havana and damaged buildings in the western province of Pinar del Rio last month, Castro didn't tour storm-ravaged areas as he often does, instead sending in Vice President Carlos Lages.

But Castro clearly continues to enjoy great stamina, giving a series of almost daily hours-long talks on state television earlier this year during which he showed no obvious tremors — the symptom many people associate with Parkinson's.

Nebraska Governor Dave Heineman told the Nebraska Tax Research Council this month about meeting Castro at a Havana reception in August in which the two chatted while standing for four hours without a break.

In Cuba to promote Nebraska agricultural products, the governor said it seemed like a test of wills: "We weren't about to sit down before he did."

Castro still travels, most recently to Jamaica in September to join his friend Venezuelan President Hugo Chavez for the launch of a Caribbean oil trading initiative. Caribbean leaders expect Castro in Barbados next month for talks on regional cooperation.

According to the U.S.-based National Parkinson Foundation, Parkinson disease is a chronic, progressive disease that results when nerve cells in a part of the midbrain either die or are impaired.

It affects one in 100 people over the age of 60. It can also affect younger people, such as actor Michael J. Fox. The late Pope John Paul II suffered from a particularly severe case of the disease.