The rope-a-dope boxing strategy is one that is strongly associated with Muhammad Ali and his fight against George Foreman in 1974 (see the video above). His rope-a-dope stance with the body lying against the ropes allows some of the blows to be absorbed by the rope's elasticity, but the blows to the head can still be brutal.

A legend in the boxing world, Ali was referred to as "The Greatest of All Time." He died in June at age 74 from respiratory complications related to his 30-year battle with Parkinson's disease.

It comes as little surprise, but new research shows the life of a boxer — and in particular the rope-a-dope style may contribute to expression of Parkinson's disease at such a young age. Researchers have found that sustaining a traumatic brain injury (TBI) with loss of consciousness early in life increases the risk of having neurological problems such as Parkinson's disease, but not Alzheimer's disease.

Paul Crane, M.D., from the University of Washington and his associates reported their findings in July in JAMA Neurology.

"These results suggest that a single TBI with loss of consciousness is not associated with an increased risk for clinical Alzheimer's disease, the accumulation of neuritic plaques, or neurofibrillary degeneration, but rather that the late-life effects of TBI may include Lewy bodies, microinfarcts, Parkinson's disease, and parkinsonism," the researchers wrote. "Traumatic brain injury with loss of consciousness sustained early in life is not innocuous and appears to be associated with neurodegenerative conditions, although not Alzheimer's."

There are numerous occupations that have long been associated with an increased risk of Parkinson's disease. A study looking at deaths between 1982 and 1991 found Parkinson's-related disease was higher in firefighters, janitors, military personnel, teachers, excavation machine operators and veterinarians. Clusters of neurodegenerative disease were also found among those who worked with solvents and pesticides.

Many factors contribute to risk for Parkinson's disease. The Utah Population Database includes more than 2.7 million individuals, and one study reviewed this group. The researchers looked at 519,061 individuals who also had a Utah death certificate and found a significantly elevated risk for Parkinson's disease death among clusters of families. They concluded there is a genetic contribution to Parkinson's disease.

Genetics, occupation, environment and lifestyle can all contribute to a risk for Parkinson's disease. Research has previously shown that the number of professional bouts for a boxer is a risk factor for having Parkinson's disease. Now, research confirms blows to the head contribute to the risk for Parkinson's disease.

"The Greatest" had a long, colorful career. Ali earned a place in history and in our hearts. But at such a cost.