Neurodegenerative diseases are debilitating conditions that result in degeneration and death of nerve cells. A significant group of these diseases is the synucleinopathies, which are characterized by the accumulation of aggregates of alpha-synuclein in neurons, nerve fibers, or glial cells. There are three main types of synucleinopathies: Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Synucleins are small, naturally unfolded proteins prone to aggregate and form intracellular inclusions, which impair normal cellular functions. This book presents new data on synuclein aggregation and its effect on cholesterol transport. It also discusses the role of genetic contribution to these diseases and approaches to inhibition of synuclein aggregation.