Initiation and inhibition deficits, syndromes, and cognitive competency in schizophrenia
Date
2017-08-30
Authors
Christensen, Karin Maria
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Abstract
Deficits in attention, memory, and executive functioning have been associated with schizophrenia. Neuropsychological functioning is considered to bridge neuropathology and clinical symptoms in this illness. However, relatively few studies have investigated the connections between specific cognitive deficits and other variables. “Psychomotor poverty” and “disorganization” are two of the three schizophrenia syndromes. Previous work suggests that neuropsychological deficits in the initiation and inhibition of thoughts and actions underlie psychomotor poverty and disorganization, respectively. Part of this study aimed to replicate and extend these findings. Unstructured tasks were used, because they elicit impairments in executive functioning.
The present study also examined the effects of neuropsychological functioning and syndromes on overall cognitive competency. Cognitive competency refers to the integrity of cognitive skills important for independent functioning in everyday life. Though often neglected, cognitive competency is an important functional outcome. It was hypothesized that both psychomotor poverty and disorganization would predict reduced cognitive competency.
Participants were 40 in- and outpatients, aged 17 to 51 years, with a current diagnosis of schizophrenia according to DSM-IV criteria. A psychiatrist rated symptomatology using the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms. Two unstructured neuropsychological tasks were administered: a verbal description of a picture and the Tinkertoy test. Using these tasks, measures of initiation and inhibition capacity were developed; these revealed good interrater reliability. The Cognitive Competency Test used simulated situations to evaluate cognition in areas that affect everyday functioning. Finally, a brief insight measure was included for exploratory analyses.
Data were analyzed within the framework of a causal model. Initiation capacity failed to predict the psychomotor poverty syndrome. One indicator of disinhibition—intermingling—predicted the disorganization syndrome. Disorganization mediated the impact of intermingling on cognitive competency. In contrast, initiation capacity affected cognitive competency directly. Insight correlated with the disorganization syndrome, and contributed to the prediction of cognitive competency. Initiation, disorganization syndrome, and insight, combined, accounted for 58% of the variance in cognitive competency; each variable contributed uniquely. Implications include suggestions as to which deficits and syndromes should be targeted for remediation, to improve patients' independent functioning.
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Schizophrenia