The present invention relates to a new use of 4-phenoxy-phenyl-1,3,5-triazine derivatives or pharmaceutically acceptable salts thereof, according to formula I, wherein R1, R2 and U have meanings as provided in the description, as medicaments for the treatment and/or prevention of diseases characterised by impaired signalling of neurotrophins and/or other trophic factors. In particular, the invention relates to the treatment of such diseases in patients with the Val66Met mutation in the brain-derived neurotrophic factor gene.