In a recent study, 33 polio survivors were given neuropsychologic tests of word finding, attention and thinking speed and had the blood hormone prolactin measured. An elevated prolactin level indicates low levels of the neurochemical dopamine in the brain.

"Polio survivors with severe daily fatigue had significant word-finding difficulty," said Dr. Richard L. Bruno, director of The Post-Polio Institute at Englewood Hospital and Medical Center. "We also found that those with word-finding difficulty also had impaired attention, thinking speed and higher prolactin levels, suggesting that they had lower brain dopamine."

Dr. Bruno said that the word-finding difficulty, impaired attention and slower thinking speed – as well as disabling fatigue – result from polio survivors’ brains making too little dopamine. This conclusion is supported by two other Post-Polio Institute studies. A 1998 study found that polio survivors with severe fatigue have higher prolactin levels and slowing of their brain waves. A 1996 study showed that bromocriptine, a dopamine-replacing drug used to treat Parkinson’s disease, reduced fatigue, word-finding difficulty and attention problems in polio survivors with severe fatigue.

"Autopsies performed 50 years ago on patients who died after having had polio show that the poliovirus damaged the brain neurons that make dopamine," said Dr. Bruno. "Dopamine-producing neurons were killed in the brain, whether or not the poliovirus damaged the spinal cord, and caused paralysis."

The Post-Polio Institute’s 1990 National Post-Polio Survey found that 91 percent of the estimated 1.8 million North American polio survivors report fatigue, and that 70 percent to 96 percent of polio survivors with fatigue report difficulty with word-finding, attention and thinking quickly. "Since fatigue is the most commonly reported and most disabling symptom of Post-Polio Syndrome, many polio survivors have ‘thinking problems’ and are afraid they have Alzheimer’s disease," said Dr. Bruno.

But Dr. Bruno’s work has found that polio survivors’ thinking problems are similar to those in Parkinson’s disease, which is known to be caused by low levels of brain dopamine, and not Alzheimer’s disease, as so many fear. "Many Parkinson’s patients demonstrate disabling fatigue, problems with attention and word-finding difficulty," said Dr. Bruno. "Fortunately, the poliovirus did not kill enough dopamine-producing neurons to cause the physical symptoms – tremor and rigidity – that are seen in Parkinson’s disease.

"Thinking problems in polio survivors are not symptoms of dementia. Therefore, there is no reason to suspect Alzheimer’s disease," added Dr. Bruno. "Our work over the past 15 years shows that reducing physical overexertion can decrease word-finding difficulty, problems with attention and fatigue in polio survivors."

Parkinson’s sufferer and actor Michael J. Fox found he needed to change his priorities, and reduce exertion. Polio survivors benefit from changing their priorities, too. For more information, contact The Post-Polio Institute at Englewood Hospital and Medical Center, 201-894-3724.