title: The LonDownS adult cognitive assessment to study cognitive abilities and decline in Down syndrome.
abstract: BACKGROUND
  Down syndrome (DS), the most common genetic cause of intellectual disability, is associated with an ultra-high risk of developing Alzheimer's disease. However, there is individual variability in the onset of clinical dementia and in baseline cognitive abilities prior to decline, particularly in memory, executive functioning, and motor coordination. The LonDownS Consortium aims to determine risk and protective factors for the development of dementia and factors relating to cognitive abilities in people with DS. Here we describe our cognitive test battery and related informant measures along with reporting data from our baseline cognitive and informant assessments.
  
  
  METHODS
  We developed a cognitive test battery to assess general abilities, memory, executive function, and motor coordination abilities in adults with DS, with informant ratings of similar domains also collected, designed to allow for data on a broad range of participants. Participants (n=305) had a range of ages and abilities, and included adults with and without a clinical diagnosis of dementia.
  
  
  RESULTS
  Results suggest the battery is suitable for the majority of adults with DS, although approximately half the adults with dementia were unable to undertake any cognitive task. Many test outcomes showed a range of scores with low floor and ceiling effects. Non-verbal age-adjusted IQ scores had lower floor effects than verbal IQ scores. Before the onset of any cognitive decline, females aged 16-35 showed better verbal abilities compared to males. We also identified clusters of cognitive test scores within our battery related to visuospatial memory, motor coordination, language abilities, and processing speed / sustained attention.
  
  
  CONCLUSIONS
  Our further studies will use baseline and longitudinal assessments to explore factors influencing cognitive abilities and cognitive decline related to ageing and onset of dementia in adults with DS.
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.|The LonDownS Consortium, University College London, London, UK.
authors.forename: Carla M
authors.identifier: 0000-0001-9261-9924
authors.initials: CM
authors.lastname: Startin
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.|The LonDownS Consortium, University College London, London, UK.
authors.forename: Sarah
authors.initials: S
authors.lastname: Hamburg
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.|The LonDownS Consortium, University College London, London, UK.
authors.forename: Rosalyn
authors.initials: R
authors.lastname: Hithersay
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.|Faculty of Health and Medical Sciences, University of Surrey, Guilford, UK.
authors.forename: Amy
authors.initials: A
authors.lastname: Davies
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.
authors.forename: Erin
authors.initials: E
authors.lastname: Rodger
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Aggarwal
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.|The LonDownS Consortium, University College London, London, UK.
authors.forename: Tamara
authors.initials: T
authors.lastname: Al-Janabi
authors.affiliation: UCL Division of Psychiatry, University College London, London, UK.|The LonDownS Consortium, University College London, London, UK.
authors.forename: André
authors.initials: A
authors.lastname: Strydom
keywords: Alzheimer’s disease; Down syndrome; cognition; dementia; executive function; intellectual disability; memory; motor coordination