1 Department of Geriatric Psychiatry, Akershus University Hospital, Sykehusveien 25, 1478, Lørenskog, Norway. nikias.siafarikas@googlemail.com.
2 Faculty of Medicine, University of Oslo, Oslo, Norway. nikias.siafarikas@googlemail.com.
3 Department of Neurology, University Hospital of North Norway, Tromsø, Norway.
4 Department of Psychology, Faculty of Health Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
5 Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE5 9NU, UK.
6 Department of Geriatric Psychiatry, Akershus University Hospital, Sykehusveien 25, 1478, Lørenskog, Norway.
7 Department of Neurology, Akershus University Hospital, Lørenskog, Norway.
8 Department of Psychology, University of Oslo, Oslo, Norway.
9 Faculty of Medicine, University of Oslo, Oslo, Norway.
10 Norwegian National Advisory Unit On Aging and Health, Vestfold Hospital Trust, Tønsberg, Norway.
11 Department of Geriatric Medicine, Oslo University Hospital, Oslo, Norway.
12 Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
13 Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.
14 Department of Old Age Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE5 8AF, UK.
15 Institute of Clinical Medicine, University of Oslo, Campus Ahus, Oslo, Norway.