Recently, research has linked deficits in neurocognition, which emerge early in schizophrenia, with psychosocial impairments. However, it is uncertain how these deficits lead to sustained dysfunction. In this review, we explore how neurocognitive deficits could disrupt function at three levels: learning, coping preference, and self-concept. We offer a model in which neurocognitive impairment may directly limit skills acquisition and the development of a rich personal narrative. We suggest that both limited skills acquisition and an impoverished narrative may subsequently feed into a habitual style of avoidant coping, leading to a cycle of sustained dysfunction. Implications for cognitive, rehabilitation, and psychotherapeutic interventions are discussed.
[Show abstract][Hide abstract] ABSTRACT: This article reviews how functional neuroimaging research of cognitive dysfunction in schizophrenia has resulted in a progression of influential pathophysiological models of the disorder. The review begins with discussion of the 'hypofrontality' model, moving from resting studies examining anterior to posterior gradients of cerebral blood flow (CBF), to cognitive activation studies employing the Wisconsin Card Sorting Test, and current functional magnetic resonance imaging (fMRI) studies of working memory and cognitive control utilizing parametric task designs and event-related procedures. A similar progression is described for development of the temporal lobe model of schizophrenia, moving from research on the temporal cortex and language processing to the hippocampal formation and long-term memory (LTM). These LTM studies found that hippocampal dysfunction was often accompanied by disrupted prefrontal function, supporting a hybrid model of impaired fronto-temporal connectivity. Developments in image analysis procedures are described that allow assessment of these distributed network models. However, given limitations in temporal and spatial resolution, current methods do not provide 'real-time' imaging of network activity, making arrival at a definitive pathophysiologic mechanism difficult. Dorsolateral prefrontal cortex (DLPFC) dysfunction and disrupted fronto-temporal integration appear to be equally viable current models. The article concludes with a discussion of how fMRI can help facilitate development of novel psychosocial and pharmacological interventions designed to improve cognition and functional outcome in patients with schizophrenia.
International Review of Psychiatry 09/2007; 19(4):417-27. DOI:10.1080/09540260701486365 · 1.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Patients with schizophrenia have pronounced deficits in memory for events--episodic memory. These deficits severely affect patients' quality of life and functional outcome, and current medications have only a modest effect, making episodic memory an important domain for translational development of clinical trial paradigms. The current article provides a brief review of the significant progress that cognitive neuroscience has made in understanding basic mechanisms of episodic memory formation and retrieval that were presented and discussed at the first CNTRICS (Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia) meeting in Washington, D.C. During that meeting a collaborative decision was made that measures of item-specific and relational memory were the most promising constructs for immediate translational development. A brief summary of research on episodic memory in schizophrenia is presented to provide a context for investigating item-specific and relational memory processes. Candidate brain regions are also discussed.
[Show abstract][Hide abstract] ABSTRACT: Functional recovery among treated bipolar disorder (BPD) patients is far less likely than syndromal and even symptomatic recovery. We hypothesized that increasingly well-documented aspects of cognitive impairment may contribute to poor functional outcomes in BPD patients, and reviewed the available research on the topic.
Computerized literature searching identified 12 studies with 13 comparisons that simultaneously evaluated cognitive and functional status in euthymic (n = 8) or non-euthymic (n = 5 comparisons) adult BPD patients versus otherwise similar healthy controls.
In 6/8 studies of euthymic BPD patients and 5/5 studies of non-euthymic BPD patients, neurocognitive impairment was significantly associated with impaired psychosocial functioning, even after adjusting for residual mood symptoms and relevant demographic and clinical variables. Cognitive status was consistently assessed with standardized, performance-based neuropsychological tests, but functional status usually was based on subjective self-appraisals. Approximately 55% of BPD patients were unemployed.
Available studies are limited by subjective assessments of functional status rather than objective, performance-based measures. Nevertheless, they support the hypothesis that enduring aspects of cognitive impairment found even in euthymic BPD patients are associated with inferior functioning. These findings encourage further studies with better assessment methods and greater rehabilitative efforts in BPD patients.
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