Updates and advances in the treatment of Parkinson disease.

Parkinson disease (PD) is a complex neurodegenerative disorder that can present heterogeneously with a combination of motor and non-motor symptoms. α-synuclein, a neuronal protein, can undergo aberrant conformational change resulting in the intra-neuronal accumulation of toxic oligomers that form Lewy bodies, the pathological hallmark of PD. There is evidence that pathological α-synuclein exhibits prion-like behaviour in its mode of transmission through the nervous system. The choice of initial dopaminergic treatments should be individually tailored but long term outcomes appear to be equivalent. There is level A evidence supporting the benefit of three different device-assisted therapies in treating troublesome motor fluctuations and dyskinesias. Stem cell transplantation as currently being trialled is predominantly a symptomatic therapy targeting only limited regions of the brain affected by PD, and will need to be proven to be not only as effective but as safe as currently available device-assisted therapies. New modes of treatment including active immunisation against oligomeric α-synuclein and drugs that alter cellular metabolism show some promise. The inability to effectively treat a range of non-motor, non-dopaminergic symptoms remains a major therapeutic challenge.