Risk Factors Suggest Preclinical Parkinson's: Look for Excessive Daytime Sleepiness, Olfactory Dysfunction, Constipation, and Slow Reaction Time

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WASHINGTON -- The presence of constipation, poor olfaction, slow reaction time, and excessive daytime sleepiness in any combination strongly suggests the presence of preclinical Parkinson's disease, according to findings from the ongoing Honolulu-Asia Aging Study presented at the World Parkinson Congress.

Dr. G. Webster Ross of the University of Hawaii in Honolulu and his colleagues on the Honolulu-Asia Aging Study (HAAS) have been able to assess the relationship between these four factors and, not only Parkinson's disease (PD), but the presence of Lewy bodies in the brain as well.

HAAS began in 1965 as the Honolulu Heart Program, a prospective study of heart disease and stroke that followed a cohort of 8,000 Japanese-American men (all born between 1900 and 1919). The aging component of the study began in 1991 with case findings for dementia and Parkinson's disease. The researchers have continued to identify cases through examinations in 1994, 1997, 1999, 2001, and 2003. The researchers also have continued surveillance of hospital death records in order to confirm diagnoses. Preclinical determinants were assessed prior to the diagnosis of PD.

An autopsy study began in 1991. Since then, the researchers have been examining stained sections of the substantia nigra, the locus coeruleus, and the amygdala for the presence of Lewy bodies. If Lewy bodies are found in any of these three areas, the researchers then look for cortical Lewy bodies as well.

"We have been able to identify those individuals with incidental Lewy bodies--that is, those that occur in decedents without dementia or Parkinson's disease," Dr. Ross said. "We have used this incidental Lewy body stage as an ... end point in addition to Parkinson's disease, with the idea that if we find risk factors or predictors of both of these conditions that it's plausible evidence that [the risk factors] probably are truly associated with the disease or with the underlying pathophysiologic process."

The researchers recently looked at how combinations of four factors--excessive daytime sleepiness (EDS), olfactory dysfunction, constipation, and slow reaction time--might be related to the incidence of PD. For constipation and slow reaction time, they found that the incidence of PD was 1 in 1,370 for those with neither symptom, 13 in 1,402 for those with one symptom, and 4 in 82 for those with both symptoms.

They also looked at the combination of EDS and olfactory dysfunction. The incidence of Parkinson's was 1 in 370 for those with neither symptom, 5 in 452 for those with one symptom, and 2 in 32 for those with both symptoms.

They then looked at the combination of EDS, olfactory dysfunction, and slow reaction time. …