1 Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, S-431 80 Mölndal, Sweden; Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, S-431 80 Mölndal, Sweden; UK Dementia Research Institute at UCL, London WC1E 6BT, UK; UCL Institute of Neurology, Department of Neurodegenerative Disease, Queen Square, London WC1N 3BG, UK. Electronic address: henrik.zetterberg@gu.se.
2 University Medical Center, Department of Neurology, Robert-Koch Strasse 40, 37075 Goettingen, Germany.