Despite the growth in new drugs for the treatment of idiopathic Parkinson's disease, high quality evidence from randomised controlled trials to guide clinicians on choosing the most appropriate therapy is scarce. Monoamine oxidase type B inhibitors (MAOBIs) have been available for about 30 years. Their popularity was boosted in the 1980s when researchers proposed that they may have a neuroprotective effect and hence alter the natural history of disease rather than merely provide symptomatic relief. Subsequently one report of increased mortality in patients given selegiline with levodopa dented this popularity.1 In this issue, Ives et al provide us with a useful summary of the trials on MAOBIs for the treatment of Parkinson's disease (p 593).2

Of the 17 trials, most are short term studies—only seven have follow up data of over 18 months. In addition, most of the trials compare a MAOBI with placebo. These trials show that MAOBIs reduce symptoms compared with placebo and allow patients to be treated with lower doses of levodopa or delay the need to start taking levodopa. However, they provide no evidence that …