Cognitive Impairment in Schizophrenia and Affective Psychoses: Implications for DSM-V Criteria and Beyond

Abstract

It has recently been suggested that the diagnostic criteria of schizophrenia should include specific reference to cognitive impairments characterizing the disorder. Arguments in support of this assertion contend that such inclusion would not only serve to increase the awareness of cognitive deficits in affected patients, among both clinicians and researchers alike, but also increase the ''point of rarity'' between schizophrenia and mood disorders. The aim of the current article is to examine this latter assertion in light of the recent opinion piece provided by Keefe and Fenton (Keefe RSE, Fenton WS. How should DSM-V criteria for schizophrenia include cognitive impairment? Schizophr Bull. 2007;33:912-920). Through literature review, we explore the issue of whether cognitive deficits do in fact differentiate the major psychoses. The overall results of this inquiry suggest that inclusion of cognitive impairment criteria in Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) (DSM-V) would not provide a major advancement in discriminating schizophrenia from bipolar disorder and affective psychoses. Therefore, while cognitive impairment should be included in DSM-V, it should not dictate diagnostic specificity-at least not until more comprehensive evidence-based reviews of the current diagnostic system have been undertaken. Based on this evidence, we consider several alternatives for the DSM-V definition of cognitive impairment in schizophrenia, including (1) the inclusion of cognitive impairment as a specifier and (2) the definition of cognitive impairment as a dimension within a hybrid categorical-dimensional system. Given the state of current evidence, these possibilities appear to represent the most parsimonious approaches to the inclusion of cognitive deficits in the diagnostic criteria of schizophrenia and, potentially, of mood disorders.

A-582941, cholinergic alpha 7 nicotinic receptor agonist, improved cognitive and negative symptoms of the sub-chronic MK-801 model of schizophrenia in rats

“…Positive and negative symptoms such as hallucination, delusion, paranoia, social withdrawal, and anhedonia are more prominent symptoms of schizophrenia, while 80% of schizophrenic patients have cognitive impairments in different types of memory [2]. Even though positive symptoms can be improved by both typical and atypical antipsychotics, negative symptoms and cognitive deficits are still unmet needs for schizophrenia treatment.…”

Neurodevelopmental origin of cognitive impairment in schizophrenia

“…Schizophrenia is associated with substantial cognitive dysfunction (Gold & Harvey, 1993;Heinrichs & Zakzanis, 1998;Bora et al 2010). Neurocognitive deficits are persistent characteristics of schizophrenia throughout the illness and are predictors of level of functioning (Green, 1996;Bora et al 2010;Kahn & Keefe, 2013).…”

Dementia in schizophrenia

“…Diagnosis at this stage would be made easier if cognitive testing early in the lifespan of patients with schizophrenia were routine. There is a growing consensus that cognitive deficits characterising schizophrenia should be incorporated into the major diagnostic systems, including the DSM and ICD (Bora 2010). Such a development would prompt clinicians to assess a patient's cognitive profile early in the course of schizophrenia.…”