Parkinson's Signs Linked to Alzheimer's
Parkinson's-like Symptoms Tied to Risk of Alzheimer's Disease
April 22, 2003 -- Older adults who rapidly develop the tremors and other classical symptoms of Parkinson's disease may be up to eight times as likely to develop Alzheimer's disease. A new study shows that the progression of symptoms traditionally associated with Parkinson's disease, such as an irregular gait, muscle rigidity, tremors, and limited movement, are also linked to a decline in mental functioning and the development of Alzheimer's disease.
Researchers say Parkinson's disease-like symptoms are common in older people with and without Alzheimer's disease, but the link between the progression or severity of these muscle-related symptoms and later development of Alzheimer's disease has not been studied until now.
Their study, published in the April issue of The Archives of Neurology, tracked the progression of symptoms associated with Parkinson's disease among 824 Catholic clergy members with an average age of 75 who had no signs of Alzheimer's or Parkinson's disease at the start of the study.
After an average of about four and a half years of follow-up, 79% of the participants experienced at least some progression of Parkinson's disease-like symptoms, according to a standard test that measures signs of Parkinson's disease. Compared with the 21% who did not experience any worsening of symptoms, researchers found those who had the most rapid progression were more than eight times as likely to develop Alzheimer's disease.
Overall, 114 of the participants developed Alzheimer's disease. But the study found the odds of developing Alzheimer's were closely related to the speed at which they developed muscular symptoms associated with Parkinson's disease. For example, those with moderate progression of symptoms were three times more likely to develop Alzheimer's, and those with the least rapid progression had twice the risk of Alzheimer's compare with those without symptoms.
Researcher Robert Wilson, PhD, of Rush-Presbyterian-St. Luke's Medical Center in Chicago, and colleagues, say the rate of progression of symptoms, especially worsening gait and rigidity, was also linked to scores on tests that measured mental function. As the person's physical symptoms worsened, his or her mental functioning also declined, and more rapid physical decline was associated with more rapid mental decline.
Researchers say the results suggest that the progression of symptoms traditionally found in Parkinson's disease in older persons is also related to the development of Alzheimer's disease. But they say further studies are needed in a more diverse group of people to confirm these findings.
SOURCE: The Archives of Neurology, April 2003.