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Information processing

What is information processing? 

Information processing involves a number of cognitive functions, including perception, attention, memory and decision making, as well as the speed at which these cognitive functions are executed. Any impairment in information processing can reflect impairments in these other cognitive domains. Information processing can be assessed using various tests. The Wechsler Adult Intelligence Scale (WAIS) digit symbol coding test presents participants with paired numbers and symbols and when shown several numbers, participants must write down the missing corresponding symbols as quickly as possible. The Wisconsin Card Sorting Task (WCST) requires an ability to shift cognitive sets; participants are asked to match stimulus cards, with feedback provided as to whether the match was correct or incorrect based on a colour, quantity, or design rule that changes during the task. The Trail Making Test (TMT) requires participants to connect, in order, letters and/or numbers as quickly as possible. The Stroop Colour Word Test (SCWT), 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. Category fluency is an oral test that requires participants to name as many items in a category (e.g. furniture items) as they can in one minute.

What is the evidence for information processing?

Compared to people without schizophrenia, high quality evidence shows a large effect of poor information processing in people with first-episode or chronic schizophrenia. Moderate to low quality evidence also suggests poor performance in people with youth-onset or late-onset schizophrenia. Compared to people with affective psychoses (e.g. bipolar disorder), high quality evidence shows a small effect of poor information processing on TMT and WCST. Moderate to low quality evidence suggests greater impairment in deficit schizophrenia (predominately negative symptoms) compared to non-deficit schizophrenia in both speeded and non-speeded information processing tasks. High quality evidence shows that better information processing may have a medium-sized association with better community functioning and a weak association with less severe symptoms. People at clinical high risk of psychosis or familial high risk of psychosis are similarly impaired in processing speed. There is similar, small improvements in processing speed over time (1-5 years) in people at ultra-high risk of psychosis, in people with first-episode psychosis, and in people without schizophrenia.

High quality evidence shows greater improvements in processing speed in patients taking second generation antipsychotics compared to patients taking first generation antipsychotics. Moderate to high quality evidence suggests patients taking olanzapine, clozapine or risperidone show improvements in processing speed after treatment, while patients taking quetiapine show no improvement. High quality evidence also suggests no improvement with haloperidol.


April 2016

Page last updated: 4:11  6 September 2017

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