Drewster, thank you for your reply. You are right in saying that we don't know for sure whether anti-aggregation strategies are safe. But, being 10 years post-diagnosis, I don't have the luxury of waiting for research to progress entirely safely; and, even then, possibly to find that the therapy is made so expensive that it cannot be accessed.
In vitro experiments show that nicotine, caffeine, curcumin and cumin slow the fibrillation of alpha-synuclein. There is epidemiological evidence that these substances are associated with a lower prevalence of PD. (But a course of treatment that lowers prevalence does not necessarily mean that it would slow progression).
The case for nicotine in the treatment of PD is described by Barreto et al..
 Front. Aging Neurosci., 09 January 2015 | http://dx.doi.org/10.3389/fnagi.2014.00340
Beneficial effects of nicotine, cotinine and its metabolites as potential agents for Parkinson’s disease
George Barreto et al.