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Title: Neurocognitive functioning in schizophrenia and bipolar disorder: Clarifying concepts of diagnostic dichotomy vs. continuum
Authors: Kuswanto, C.N
Sum, M.Y
Sim, K 
Keywords: chlorpromazine
bipolar disorder
Brief Assessment of Cognition battery
cognitive defect
controlled study
cross-sectional study
disease duration
disease severity
genetic association
Global Assessment of Functioning
intelligence quotient
major clinical study
neurocognitive functioning
Positive and Negative Syndrome Scale
right handedness
semantic memory
social psychology
task performance
verbal memory
working memory
Young Mania Rating Scale
Issue Date: 2013
Citation: Kuswanto, C.N, Sum, M.Y, Sim, K (2013). Neurocognitive functioning in schizophrenia and bipolar disorder: Clarifying concepts of diagnostic dichotomy vs. continuum. Frontiers in Psychiatry 4 (DEC) : Article 162. ScholarBank@NUS Repository.
Rights: Attribution 4.0 International
Abstract: The Kraepelinian dichotomy posits that patients with schizophrenia (SCZ) and bipolar disorder (BD) present as two separate psychotic entities such that they differ in terms of clinical severity including neurocognitive functioning. Our study aimed to specifically compare and contrast the level of neurocognitive functioning between SCZ and BD patients and identify predictors of their poor neurocognitive functioning. We hypothesized that patients with SCZ had a similar level of neurocognitive impairment compared with BD. About 49 healthy controls (HC), 72 SCZ, and 42 BD patients who were matched for age, gender, and premorbid IQ were administered the Brief Assessment of Cognition battery (BAC). Severity of psychopathology and socio-occupational functioning were assessed for both patients groups. Both BD and SCZ groups demonstrated similar patterns of neurocognitive deficits across several domains (verbal memory, working memory, semantic fluency, processing speed) compared with HC subjects. However, no significant difference was found in neurocognitive functioning between BD and SCZ patients, suggesting that both patient groups suffer the same degree of neurocognitive impairment. Patients with lower level of psychosocial functioning [F(1,112) = 2.661, p = 0.009] and older age [F(1,112) = -2.625, p = 0.010], not diagnosis or doses of psychotropic medications, predicted poorer overall neurocognitive functioning as measured by the lower BAC composite score. Our findings of comparable neurocognitive impairments between SCZ and BD affirm our hypothesis and support less the Kraepelinian concept of dichotomy but more of a continuum of psychotic spectrum conditions. This should urge clinicians to investigate further the underlying neural basis of these neurocognitive deficits, and be attentive to the associated socio-demographic and clinical profile in order to recognize and optimize early the management of the widespread neurocognitive deficits in patients with SCZ and BD. © 2013 Kuswanto, Sum and Sim.
Source Title: Frontiers in Psychiatry
ISSN: 16640640
DOI: 10.3389/fpsyt.2013.00162
Rights: Attribution 4.0 International
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