Executive functioning in schizophrenia: Unique and shared variance with measures of fluid intelligence


We examine fluid intelligence and executive functioning in schizophrenia.

Fluid intelligence does not explain all differences in executive functioning.

How fluid intelligence is measured is important.

Executive functioning measures are important for understanding schizophrenia.


Patients with schizophrenia often display deficits on tasks thought to measure “executive” processes. Recently, it has been suggested that reductions in fluid intelligence test performance entirely explain deficits reported for patients with focal frontal lesions on classical executive tasks. For patients with schizophrenia, it is unclear whether deficits on executive tasks are entirely accountable by fluid intelligence and representative of a common general process or best accounted for by distinct contributions to the cognitive profile of schizophrenia.

In the current study, 50 patients with schizophrenia and 50 age, sex and premorbid intelligence matched controls were assessed using a broad neuropsychological battery, including tasks considered sensitive to executive abilities, namely the Hayling Sentence Completion Test (HSCT), word fluency, Stroop test, digit-span backwards, and spatial working memory. Fluid intelligence was measured using both the Matrix reasoning subtest from the Weschler Abbreviated Scale of Intelligence (WASI) and a composite score derived from a number of cognitive tests.

Patients with schizophrenia were impaired on all cognitive measures compared with controls, except smell identification and the optimal betting and risk-taking measures from the Cambridge Gambling Task. After introducing fluid intelligence as a covariate, significant differences remained for HSCT suppression errors, and classical executive function tests such as the Stroop test and semantic/phonemic word fluency, regardless of which fluid intelligence measure was included.

Fluid intelligence does not entirely explain impaired performance on all tests considered as reflecting “executive” processes. For schizophrenia, these measures should remain part of a comprehensive neuropsychological assessment alongside a measure of fluid intelligence.

Cognition; Frontal lobes; Word fluency; Hayling; Stroop; Fluid intelligence; Schizophrenia

I have a sz spectrum disorder(paranoid personality) rather than sz. An online test mentioned by years ago and not now available) showed my executive functioning was significantly below average.
The problem for me is especially relevant re organising and planning. Tasks requiring a multi step approach are problematic.

I would suspect quite a few of us here whether diagnosed with sz or a sz spectrum disorder would have problems with executive functioning. I don’t think it is much helped by medication though maybe cognitive training(if you can get it) might help.
I think it has a negative effect on daily functioning.

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