WEDNESDAY, July 28 (HealthDay News) -- Parkinson's disease, multiple system atrophy, and dementia with Lewy bodies may have preclinical periods lasting for decades in some cases, with the initial manifestation being idiopathic REM sleep behavior disorder (RBD), according to research published online July 28 in Neurology.

Daniel O. Claassen, M.D., of the Mayo Clinic College of Medicine in Rochester, Minn., and colleagues analyzed data from 27 patients with a history of RBD that preceded the onset of clinical Parkinson's disease, Parkinson's dementia, multiple system atrophy, or dementia with Lewy bodies by at least 15 years. Twenty-four of the patients were male.

The researchers found that the length of time between RBD and the neurological syndrome was a median 25 years, but ranged up to 50 years. Primary motor symptoms occurred in 13 patients at initial presentation -- nine with Parkinson's disease, three with Parkinson's and mild cognitive impairment, and one with Parkinson's disease dementia. Primary cognitive symptoms occurred in 13 patients, 10 of whom had probable dementia with Lewy bodies and three of whom had mild cognitive impairment. One patient, diagnosed with multiple system atrophy, presented with primary autonomic symptoms. At the latest follow-up, 63 percent of patients had progressed to dementia.

"By the time the typical motor symptoms of the synucleinopathies are apparent, widespread and longstanding central and peripheral neuropathologic changes have already occurred," write the authors of an accompanying editorial. "The subtle and protean early non-motor manifestations of the synucleinopathies must be identified early, allowing the use of effective neuroprotective treatments as they become available."

One author disclosed financial ties to Cephalon Inc.

Abstract
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