Recent data obtained in animals and in humans suggest that both MAO-A and MAO-B inhibitors present cognitive enhancing properties of possible interest in the treatment of cognitive disorders. In addition, the rational for using selegiline as a neuroprotector in Parkinson's disease may also be applicable in Alzheimer's disease in which a dramatic increase in the MAO-B activity has been reported. It seems then worthwhile to investigate the neuroprotective effect of MAOIs in humans and to assess, furthermore, the real therapeutical benefit of their cognitive enhancing properties.