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L-Deprenyl, a specific MAO-B inhibitor, has been reported to improve learning/memory in some cognitive tests in aged rats. The present study investigated whether L-deprenyl could alleviate the spatial learning deficit induced by muscarinic blockade and aging in OFA rats. Scopolamine (0.25 mg/kg) impaired the acquisition of a water maze task in adult rats and increased their swimming speeds. L-Deprenyl (0.25 mg/kg, 14 days) had no effect on water maze performance in saline treated adult rats, but markedly alleviated the learning deficit induced by scopolamine and increased the time and distance of swimming in the training quadrant when the platform was removed (spatial probe trial). L-Deprenyl partly reduced the effect of scopolamine on speed of swimming. Nevertheless, administration of l-deprenyl (0.25 mg/kg, 14 days) had no effect on spatial learning/memory in aged rats. We suggest that the l-deprenyl-scopolamine interaction in the water maze test may be considered as a premise for further investigations of l-deprenyl as cognition enhancer.

A double-blind, cross-over trial with 12 patients with Alzheimer's disease (AD) was carried out primarily to test the suitability of this design in the investigation of the clinical, effects of selegiline (10 mg/day) in AD. Cerebrospinal fluid (CSF) samples for the determination of concentrations of noradrenaline (NA) and several monoamine metabolites were collected at baseline and at the end of both four-week treatment periods (placebo and selegiline). The severity of dementia was assessed using Ferm's and Gottfries-Bråne-Steen (GBS) dementia scales. The concentrations of the dopamine metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC) and the NA metabolites, 3,4-dihydroxyphenylglycol (DHPG), and 3-methoxy-4-hydroxyphenyl glycol (MHPG) decreased significantly during selegiline treatment. There was a clear trend of reduction in concentrations of homovanillic acid (HVA) during selegiline treatment, whereas the concentrations of NA, 5-hydroxyindoleacetic acid (5-HIAA), and tryptophan did not differ significantly. The study design was not suitable for the analysis of the clinical results as there was a significant carry-over effect in both scales. As only the first period data could be used in the analysis, there were no significant differences in the scores of Ferm's or GBS scales, but clear positive trends could be detected in favour of selegiline.