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The cognitive profile of ALS: a systematic review and meta-analysis update
  1. Emma Beeldman1,
  2. Joost Raaphorst1,2,
  3. Michelle Klein Twennaar1,
  4. Marianne de Visser1,
  5. Ben A Schmand1,3,
  6. Rob J de Haan4
  1. 1Department of Neurology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
  2. 2Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands
  3. 3Department of Psychology, University of Amsterdam, Amsterdam, The Netherlands
  4. 4Clinical Research Unit, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
  1. Correspondence to Emma Beeldman, Department of Neurology, Academic Medical Centre, P.O. Box 22700 DE, Amsterdam 1105 AZ, The Netherlands; e.beeldman{at}amc.uva.nl

Abstract

Cognitive impairment is present in approximately 30% of patients with amyotrophic lateral sclerosis (ALS) and, especially when severe, has a negative impact on survival and caregiver burden. Our 2010 meta-analysis of the cognitive profile of ALS showed impairment of fluency, executive function, language and memory. However, the limited number of studies resulted in large confidence intervals. To obtain a more valid assessment, we updated the meta-analysis and included methodological improvements (controlled data extraction, risk of bias analysis and effect size calculation of individual neuropsychological tests). Embase, Medline and PsycInfo were searched for neuropsychological studies of non-demented patients with ALS and age-matched and education-matched healthy controls. Neuropsychological tests were categorised in 13 cognitive domains and effect sizes (Hedges’ g) were calculated for each domain and for individual tests administered in ≥5 studies. Subgroup analyses were performed to assess the influence of clinical and demographic variables. Forty-four studies were included comprising 1287 patients and 1130 healthy controls. All cognitive domains, except visuoperceptive functions, showed significant effect sizes compared to controls. Cognitive domains without bias due to motor impairment showed medium effect sizes (95% CI): fluency (0.56 (0.43 to 0.70)), language (0.56 (0.40 to 0.72)), social cognition (0.55 (0.34 to 0.76)), or small effect sizes: delayed verbal memory 0.47 (0.27 to 0.68)) and executive functions (0.41 (0.27 to 0.55)). Individual neuropsychological tests showed diverging effect sizes, which could be explained by bias due to motor impairment. Subgroup analyses showed no influence of bulbar disease onset and depression and anxiety on the cognitive outcomes. The cognitive profile of ALS consists of deficits in fluency, language, social cognition, executive functions and verbal memory. Social cognition is a new cognitive domain with a relatively large effect size, highlighting the overlap between ALS and frontotemporal dementia. The diverging effect sizes for individual neuropsychological tests show the importance of correction for motor impairment in patients with ALS. These findings have implications for bedside testing, the design of cognitive screening measures and full neuropsychological examinations.

  • ALS
  • COGNITION
  • META-ANALYSIS

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