BCHE and Parkinson disease: Cholinesterase inhibitors may reduce the number of falls in PD: a randomized, double‐blind, placebo‐controlled study compared rivastigmine with placebo in PD and found a 45% reduction in falls in the treatment group.43 There is similar evidence that donepezil and galantamine reduce fall frequency in PD.44, 45 Potential anticholinesterase responsiveness corroborates the suggestion that acetylcholine deficiency may be involved in PSP pathophysiology, as discussed previously.