Assessing general cognitive and adaptive abilities in adults with Down syndrome: a systematic review

Sarah Hamburg; Bryony Lowe; Carla Marie Startin; Concepcion Padilla; Antonia Coppus; Wayne Silverman; Juan Fortea; Shahid Zaman; Elizabeth Head; Benjamin L Handen; Ira Lott; Weihong Song; André Strydom

doi:10.1186/s11689-019-9279-8

Assessing general cognitive and adaptive abilities in adults with Down syndrome: a systematic review

J Neurodev Disord. 2019 Aug 30;11(1):20. doi: 10.1186/s11689-019-9279-8.

Authors

Sarah Hamburg^{1

2

3}, Bryony Lowe^{4

5

6}, Carla Marie Startin^{7

4

5}, Concepcion Padilla⁸, Antonia Coppus^{9

10}, Wayne Silverman¹¹, Juan Fortea^{12

13

14}, Shahid Zaman⁸, Elizabeth Head¹⁵, Benjamin L Handen¹⁶, Ira Lott¹⁷, Weihong Song¹⁸, André Strydom^{7

4

5}

Affiliations

¹ Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, SE5 8AF, UK. [email protected].
² Division of Psychiatry, University College London, London, W1T 7NF, UK. [email protected].
³ The London Down Syndrome Consortium (LonDownS), London, UK. [email protected].
⁴ Division of Psychiatry, University College London, London, W1T 7NF, UK.
⁵ The London Down Syndrome Consortium (LonDownS), London, UK.
⁶ Department of Psychology, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
⁷ Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, SE5 8AF, UK.
⁸ Department of Psychiatry, Herchel Smith Building for Brain & Mind Sciences, Forvie Site, Robinson Way, Cambridge, CB2 0SZ, UK.
⁹ Dichterbij, Center for Intellectual Disabilities, Gennep, The Netherlands.
¹⁰ Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands.
¹¹ Department of Pediatrics, University of California, Irvine, USA.
¹² Memory Unit, Department of Neurology, Hospital de la Santa Creu i Sant Pau-Biomedical Research Institute Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain.
¹³ Barcelona Down Medical Center, Fundació Catalana de Síndrome de Down, Barcelona, Spain.
¹⁴ Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas, CIBERNED, Madrid, Spain.
¹⁵ Sanders-Brown Center on Aging, University of Kentucky, 800 South Limestone Street, Lexington, KY, 40536-0230, USA.
¹⁶ Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA.
¹⁷ Departments of Pediatrics and Neurology, University of California, Irvine, USA.
¹⁸ Townsend Family Laboratories, Department of Psychiatry, The University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada.

Abstract

Background: Measures of general cognitive and adaptive ability in adults with Down syndrome (DS) used by previous studies vary substantially. This review summarises the different ability measures used previously, focusing on tests of intelligence quotient (IQ) and adaptive behaviour (AB), and where possible examines floor effects and differences between DS subpopulations. We aimed to use information regarding existing measures to provide recommendations for individual researchers and the DS research community.

Results: Nineteen studies reporting IQ test data met inclusion for this review, with 17 different IQ tests used. Twelve of these IQ tests were used in only one study while five were used in two different studies. Eleven studies reporting AB test data met inclusion for this review, with seven different AB tests used. The only AB scales to be used by more than one study were the Vineland Adaptive Behaviour Scale (VABS; used by three studies) and the Vineland Adaptive Behavior Scale 2nd Edition (VABS-II; used by two studies). A variety of additional factors were identified which make comparison of test scores between studies problematic, including different score types provided between studies (e.g. raw scores compared to age-equivalent scores) and different participant inclusion criteria (e.g. whether individuals with cognitive decline were excluded). Floor effects were common for IQ tests (particularly for standardised test scores). Data exists to suggest that floor effects may be minimised by the use of raw test scores rather than standardised test scores. Raw scores may, therefore, be particularly useful in longitudinal studies to track change in cognitive ability over time.

Conclusions: Studies assessing general ability in adults with DS are likely to benefit from the use of both IQ and AB scales. The DS research community may benefit from the development of reporting standards for IQ and AB data, and from the sharing of raw study data enabling further in-depth investigation of issues highlighted by this review.

Keywords: AB; Adaptive ability; Adaptive behaviour; Cognition; Down syndrome; General ability; IQ; Intelligence.

Publication types

Research Support, Non-U.S. Gov't
Systematic Review

MeSH terms

Adaptation, Psychological / physiology*
Aptitude / physiology*
Down Syndrome / diagnosis*
Down Syndrome / physiopathology
Humans
Intelligence / physiology*
Intelligence Tests*

Abstract

Publication types

MeSH terms

Grants and funding