AMANTADINE TREATMENT IS AN INDEPENDENT PREDICTOR OF IMPROVED SURVIVALIN PARKINSONS-DISEASE

Amantadine has been used for more than 20 years in the symptomatic tre atment of Parkinson's disease (PD). Several recent discoveries suggest that amantadine could also have a neuroprotective effect in PD. We st udied survival in ail parkinsonism (including PD and other parkinsonia n syndromes) patients attending a single clinic, employing standard su rvival curves and a Cox regression model, to identify independent pred ictive variables for survival (while taking into account factors poten tially associated with both outcome and treatment selection). Amantadi ne-treated patients (n = 250) were similar to the patients not treated with amantadine (n = 586) in terms of age, gender, type of parkinsoni sm, Hoehn and Yahr stage and dementia status at initial neurological v isit. Amantadine use was an independent predictor of improved survival (p < 0.01). Improved survival was also associated with a higher 10-ye ar expected survival (based on age, gender, and birth year), absence o f dementia, type of parkinsonism = PD, and low Hoehn and Yahr stage (I or II) at initial neurologic visit (all p < 0.01); these additional f actors occurred in statistically similar proportions in the groups tha t were and were not treated with amantadine. The association of improv ed survival with amantadine use may stem from symptomatic benefit or m ay reflect a ''neuroprotective'' effect, mediated through N-methyl-D-a spartate (NMDA) receptor antagonism, dopamine uptake blockade activity , or other mechanisms. Our preliminary findings suggest that a prospec tive, controlled, randomized trial of amantadine's effects on PD progr ession is warranted.