Alpha-synuclein is normally an unstructured soluble protein that can aggregate to form insoluble fibrils in pathological conditions characterized by Lewy bodies, such as Parkinson's disease, dementia with Lewy-bodies, and multiple system atrophy. In analogy to many other amyloid associated disorders, alpha-synuclein may also form oligomeric assemblies. These small and soluble forms have been suggested to exert a stronger tissue damaging effect as compared to the monomeric and fibrillar counterpart. Using a recently developed technique a monoclonal oligomer-specific antibody has been designed.