Executive functioning

What is executive functioning in schizophrenia? 

Executive functions are a group of cognitive processes involving control, mental flexibility, planning, inhibition, decision-making, initiation, abstraction, self-monitoring and pursuit of goals. Any impairment in executive functioning can also reflect impairments in other cognitive functions such as processing speed, attention, and memory. Executive functioning is most commonly measured using the Wisconsin Card Sorting Task (WCST). This task requires the ability to shift cognitive sets. Other common tasks include the Trail Making Test (TMT), which requires participants to connect, in order, letters and/or numbers as quickly as possible, and the Stroop Colour Word Test (SCWT), which presents colour names printed in an ink congruent to the colour name (e.g. blue), or incongruent to the colour name (e.g. blue); participants are asked to either read the word or name the ink colour. Verbal fluency tests involve participants naming as many words as possible from a particular category in a given time, and Go/No-Go tasks involve presenting participants stimuli in a continuous stream and asking them to make a ‘go’ or a ‘no-go’ response to each stimulus.

What is the evidence for executive functioning in schizophrenia?

Compared to people without schizophrenia, moderate to high quality evidence found people with schizophrenia show medium-sized impairments on the WCST, verbal fluency tasks, inhibition tasks, planning tasks, the TMT, the SCWT, and the Go/No-Go task. Compared to people with affective psychoses (including bipolar disorder) there were small impairments on verbal fluency tasks, the TMT, and the WCST. There were small to medium-sized impairments on the WCST in first-degree relatives of people with schizophrenia and in people at clinical high-risk of psychosis compared to people without schizophrenia. There was poorer executive functioning in individuals at clinical high-risk of psychosis who made the transition to psychosis compared to individuals at clinical high-risk of psychosis who did not make the transition to psychosis. There were similar, small improvements on executive functioning tasks over time (1 to 5 years) in people at clinical high-risk of psychosis and in people with first-episode psychosis.

Moderate to high quality evidence shows a medium-sized association between higher levels of executive functioning and higher levels of insight and lower levels of negative or disorganised symptoms (including formal thought disorder). Moderate quality evidence found no association between executive functioning and positive symptoms.

There were greater improvements in verbal fluency in people receiving second-generation antipsychotics compared to people receiving first-generation antipsychotics. People receiving quetiapine, olanzapine, or clozapine may show improvements on verbal fluency tasks post-treatment, however people receiving risperidone may show no improvement on these tasks.

March 2022

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Last updated at: 4:55 pm, 19th March 2022
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