Early-onset vs. Late-onset Parkinson's disease: A Clinical-pathological Study.

BACKGROUND: Several studies have compared early-onset Parkinson disease (EOPD) and late-onset Parkinson disease (LOPD) but most are not based on autopsy confirmed cases. METHODS: We compared clinical and pharmacological profiles, time to reach irreversible Hoehn and Yahr (H&Y) Stage 3 and levodopa motor complications in autopsy confirmed EOPD and LOPD cases. RESULTS: At first clinic visit EOPD cases were younger but had longer disease duration and they died at a younger age (all p<0.0001). Anti-Parkinsonian drug use, including levodopa, was significantly delayed in EOPD. Lifetime use of amantadine (p<0.05) and dopamine agonists (p<0.01) were higher in EOPD. While lifetime use of levodopa was similar in the two groups, levodopa was used for a significantly longer period by EOPD (p< 0.0001). EOPD had a higher cumulative incidence of dyskinesias (p<0.01), wearing-off (p<0.01), and on-off (p<0.01). However, the time to dyskinesia onset was similar in the two groups. The threshold to wearing-off was much longer in EOPD (p<0.01). H&Y stage profile at first visit was similar in the two groups. The duration from disease onset to reach irreversible H&Y stage 3 was significantly longer in EOPD. CONCLUSIONS: Our observations indicate that progression of PD is slower in EOPD and suggest that the pre-clinical interval in this group is longer. These findings can be used for case selection for drug trials and studies of the pathogenesis of PD.