New Predictors May Signal Dementia Risk in Early Parkinson's

Allison Gandey

September 30, 2008

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Dr. Ergun Uc discusses dementia rates in Parkinson's disease.

September 30, 2008 (Salt Lake City, Utah) — Early bulbar and autonomic dysfunction may predict the onset of dementia in early Parkinson's disease, report investigators. Presenting here at the American Neurological Association 133rd Annual Meeting, researchers unveiled 2 possible new predictors and outlined the incidence of dementia in early Parkinson's disease. Their findings are based on the well-known Deprenyl and Tocopherol Antioxidative Therapy for Parkinson's Disease (DATATOP), a long-term study of 800 patients with early untreated Parkinson's.

"There should be increased awareness that Parkinson's is not just a motor illness," presenter Ergun Uc, MD, from the University of Iowa, in Iowa City, told Medscape Neurology & Neurosurgery. "In our studies and elsewhere, it has been found that at the beginning of the disease, even at diagnosis, people may have mild cognitive impairment."

Such patients are at high risk of developing dementia, Dr. Uc noted. "Bulbar and autonomic dysfunction as predictors are completely novel, so that was a surprise at the beginning," he said. "But then when we thought about it, bulbar dysfunction such as speech and swallowing has many similarities to balance and gait — they are very complex, and they are governed by midline functions rather than extremity control. In a way, speech and swallowing are similar and perhaps even stronger in predicting dementia than gait and balance."

Cumulative Incidence

The original DATATOP study found that deprenyl may be effective in slowing the early progression of Parkinson's and delaying the need for levodopa. But new results suggest the beneficial effects of deprenyl may not be as lasting as investigators had first anticipated. The study also showed no evidence that tocopherol was useful in Parkinson's disease.

Researchers administered a detailed battery of tests, including cognitive tests at baseline, and obtained Mini-Mental State Examination (MMSE) scores periodically over a median follow-up period of 6.7 years.

In this secondary analysis based on DATATOP, the research team studied the cumulative incidence of dementia in 740 subjects and reported rates to be about 2.4% at 2 years and almost 6% at 5 years.

Incidence of Dementia in Clinically Confirmed Parkinson's

Timeline (y) Incidence (%) 95% CI
2 2.4 3.7 – 7.7
5 5.8 1.2 – 3.5

"This is exactly what we would have expected to see in this well-characterized patient population," Warren Olanow, MD, from the Mount Sinai School of Medicine in New York, who was on the original steering committee for the DATATOP study, said during an interview.

Baseline predictors of dementia were older age, male gender,and presence of gastrointestinal, urologic, and cardiac disorders. Predictors also included increased symmetry of parkinsonism, postural instability, gait disorder, impairment of speech and swallowing, and lower scores in cognitive tests.

During the question period following the presentation, an attendee called this "an excellent study." Another attendee pointed out that just because patients' MMSE scores may be good, that does not mean they do not have dementia or have poor social behavior, something he called an "enormous problem."

Dr. Uc said he agreed this can be a problem. "We should inquire more about mental abilities, a patient's coping with daily life, and ask about speech and swallowing issues." He pointed out that even patients who are able to engage in general conversation and may sound fine cognitively may have deficits after further neuropsychological testing.

"Vigilance should continue throughout the course of illness, because cognitive dysfunction and dementia can be a significant predictor of nursing home placement and death," Dr. Uc noted. "Patients with problems with cognition are also more likely to suffer more from side effects of medications and would also be more likely to have behavior problems."

This study was funded by the Parkinson Disease Foundation. The DATATOP trial was supported by the US Public Health Service.

American Neurological Association 133rd Annual Meeting: Derek Denny-Brown New Member Symposium. Presented September 23, 2008.

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