The invention relates the use of 4-chloro-5-{2-[4-(6-fluoro-1,2-benz[d]isoxazole-3-yl)piperidin-1-yl]ethyl-amino}-2-methyl-3-(2H)pyridazinone of the Formula (I) or pharmaceutically acceptable salts thereof for the preparation of medicaments suitable for the improvement of cognitive function or obtaining neuroprotective effect. The medicaments containing 4-chloro-5-{2-[4-(6-fluoro-1,2-benz[d]isoxazol-3-yl)piperidin-1-yl]ethyl-amino}-2-methyl-3-(2H)pyridazinone of the Formula (I) or therapeutically acceptable salt thereof can be used for the treatment or prevention of neuronal death, mental decline, sclerosis multiplex, Creuzfeld-Jacobs disease, Huntington-syndrome, amyotrophic lateral sclerosis, Parkinson-disease, memory disturbance, loss of memory, amnesia, stroke or for the improvement of memory function or learning ability.