The invention relates to methods of treating cognitive dysfunction and improving cognitive functioning comprising the administration of trans-4-((1R,3S)-6-chloro-3-phenylindan-1-yl)-1,2,2-trimethylpiperazine or a pharmaceutically acceptable salt thereof to a patient in need thereof. Moreover the invention relates to an improved binder in a composition comprising 4-((1R,3S)-6-chloro-3-phenylindan-1-yl)-1,2,2-trimethylpiperazine.