Is NADH effective in the treatment of Parkinson's disease?

Most Parkinson's disease (PD) treatments palliate symptoms by increasing nigrostriatal dopaminergic tone. A unique strategy for accomplishing this pharmacological end-point proposes using reduced nicotinamide adenine dinucleotide (NADH) to boost endogenous dopamine production, since NADH indirectly supplies reducing equivalents to the rate-limiting, tyrosine hydroxylase-catalysed step of dopamine synthesis. Support for using NADH in PD treatment includes claims that NADH stimulates tyrosine hydroxylase and dopamine biosynthesis in tissue culture and humans, as well as case series associating intravenous and oral NADH administration with PD rating scale improvements. Theoretical and practical arguments against NADH include underlying NADH disposal impairment in PD and failure of a placebo-controlled trial to show any clear benefit. While NADH may yet prove to ameliorate parkinsonism, recommendations for its use in PD are premature.