Neurocognitive deficits in schizophrenia. Are we making mountains out of molehills?

S. Moritz*, J. P. Klein, T. Desler, H. Lill, J. Gallinat, B. C. Schneider

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)

Abstract

Background: Most original studies and all meta-analyses conducted to date converge on the conclusion that patients with schizophrenia display rather generalized neurocognitive deficits. For the present study, we reopen this seemingly closed chapter and examine whether important influences, such as lack of motivation and negative attitudes towards cognitive assessment, result in poorer secondary neuropsychological performance. Method: A sample of 50 patients with an established diagnosis of schizophrenia were tested for routine neurocognitive assessment and compared to 60 nonclinical volunteers. Before and after the assessment, subjective momentary influences were examined (e.g. motivation, concerns about assessment, fear about poor outcome) for their impact on performance using a new questionnaire called the Momentary Influences, Attitudes and Motivation Impact (MIAMI) on Cognitive Performance Scale. Results: As expected, patients performed significantly worse than controls on all neurocognitive domains tested (large effect size, on average). However, patients also displayed more subjective momentary impairment, as well as more fears about the outcome and less motivation than controls. Mediation analyses indicated that these influences contributed to (secondary) poorer neurocognitive performance. Differences in neurocognitive scores shrank to a medium effect size, on average, when MIAMI scores were accounted for. Conclusions: The data argue that performance on measures of neurocognition in schizophrenia are to a considerable extent due to secondary factors. Poor motivation, fears and momentary impairments distinguished patients from controls and these variables heavily impacted performance. Before concluding that neurocognitive deficits in psychiatric patients are present, clinicians should take these confounding influences into account. Although patients with schizophrenia achieved, on average, worse test scores than controls, a large subgroup displayed spared performance.

Original languageEnglish
Pages (from-to)2602-2612
Number of pages11
JournalPsychological Medicine
Volume47
Issue number15
DOIs
Publication statusPublished - Nov 2017
Externally publishedYes

Keywords

  • effort
  • motivation
  • neurocognition
  • psychosis
  • schizophrenia

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