Early Thinking Problems May Signal Future Dementia in Parkinson's Patients
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Some people with Parkinson's go on to develop dementia, but whether it is possible to predict who will fall into this group hasn't been clear. In this new study, researchers wanted to see if early signs of thinking problems would indicate who these patients might be.
"Mild thinking problems seem to be an important clinical concept for early detection of patients with Parkinson's disease who are at risk to develop dementia," said lead researcher Dr. Kenn Freddy Pedersen, from the Norwegian Center for Movement Disorders at Stavanger University Hospital.
"Specifically, we found that more than 27 percent of patients with thinking problems at diagnosis progressed to dementia during the first three years of follow-up," he said. "Even more interesting, almost half of the patients with persistent thinking problems one year after diagnosis developed dementia during the next two years."
One result was more encouraging: For some patients, thinking ability returned to normal over the course of the study.
Although there is no immediate clinical implication to the new findings, they may be important for trials of drugs that might slow or reverse the process leading to dementia, and the findings may also help in managing patients, Pedersen said.
The report was published March 25 in the online edition of the journal JAMA Neurology.
Dr. Brian Copeland, a movement disorder fellow at the University of Texas Medical School at Houston and co-author of an accompanying journal editorial, said the study indicates that patients with ongoing evidence of thinking problems are at higher risk of getting dementia.
Although identifying patients with thinking problems is easy to do when Parkinson's disease is diagnosed, there isn't a way to accurately classify patients, so it isn't clear whether early thinking problems really predict dementia, he said.
"[The finding's] value in predicting Parkinson's disease dementia is less clear and needs further research," Copeland said.
To map the course of thinking problems in Parkinson's patients, Pedersen's team followed 182 patients for three years. Participants completed a battery of screening exams, including tests of their memory, verbal fluency and color-naming ability.
During the study, 27 percent of patients who had thinking problems at diagnosis went on to develop dementia, compared with 0.7 percent of those who didn't have thinking problems, the researchers said.
For some patients, however, normal thinking returned. Among those with thinking problems, about 19 percent saw their thinking problems clear up, Pedersen's group found.
The progression to dementia was also dependent on how severe the patient's thinking problems were, the researchers noted.
Among patients with the most severe thinking problems at the start of the study and one year later, 45.5 percent went on to develop dementia while only about 9 percent saw their thinking restored to normal, the researchers said.
Although the study found an association between mild thinking problems in patients newly diagnosed with Parkinson's disease and later dementia, it did not establish a cause-and-effect relationship.
SOURCES: Kenn Freddy Pedersen, M.D., Ph.D., Norwegian Center for Movement Disorders, Stavanger University Hospital, Norway; Brian Copeland, M.D., Movement Disorder Fellow, University of Texas Medical School at Houston; March 25, 2013, JAMA Neurology, online