Do alpha-synuclein aggregates in autonomic plexuses predate Lewy body disorders?: a cohort study.

OBJECTIVE

To determine the prevalence of alpha-synuclein (AS) aggregates in abdominopelvic autonomic plexuses in the general population and to evaluate the relationship between this finding and the subsequent development of neurologic dysfunction.

METHODS

First, surgical specimens from 100 patients (ages 44 to 84) undergoing a wide resection of an abdominopelvic organ were examined by anti-AS immunostaining. Second, 16 patients (6 AS+ and 10 randomly selected AS-) participated in yearly double-blinded neurologic assessments.

RESULTS

AS aggregates were found in autonomic plexuses in 9% of the whole sample (95% CI 3.4 to 14.6%) but were more common in vesicoprostatic (26%) than in digestive tract (4%) specimens. At 16 months after the biopsy, no prevalent cases of Parkinson disease, dementia, or autonomic failure were diagnosed among participants. One AS+ patient had previously been diagnosed with REM sleep behavior disorder. Seven of 10 control subjects but none of the 6 AS+ patients had a diagnosis of hypertension (p = 0.01). During phase IV of Valsalva maneuver, AS+ group exhibited a longer blood pressure recovery time (p = 0.03), with one patient showing absence of blood pressure overshoot. Cardiac [(123)I]metaiodobenzylguanidine uptake was reduced in the AS+ group (p = 0.03). Striatal [(123)I]ioflupane uptake was abnormally low in only one AS+ patient. At 30 months after the biopsy, lower cardiac and striatal uptake values tended to correlate with higher Unified Parkinson's Disease Rating Scale III scores (p = 0.07).

CONCLUSION

The common presence of alpha-synuclein aggregates in peripheral autonomic neurons may represent an early presymptomatic phase in the development of Lewy body disorders.