The present invention relates to peptides derivable from a component of myelin, namely myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG) or myelin proteolipid protein (PLP), for use in the treatment or prevention of impaired cognition, particularly in subjects with multiple sclerosis (MS), dementia and/or demyelination in a subject. The peptides may be used in methods of treating subjects with impaired cognition, or preventing impaired cognition, particularly in subjects with MS, treating subjects with dementia, or preventing dementia, and/or treating demyelination in a subject, or preventing demyelination in a subject.
