Computer Science Research Institute, University of Ulster, Northern Ireland;Telematica Instituut, Enschede, The Netherlands;Computer Science Research Institute, University of Ulster, Northern Ireland;Computer Science Research Institute, University of Ulster, Northern Ireland;Lulea University of Technology, Sweden;Depart. Of Psychiatry/Alzheimer center, VU University medical center, The Netherlands;Depart. Of Psychiatry/Alzheimer center, VU University medical center, The Netherlands;Telematica Instituut, Enschede, The Netherlands;Belfast City Hospital/Queen's University of Belfast, Northern Ireland;Computer Science Research Institute, University of Ulster, Northern Ireland;Lulea University of Technology, Sweden