Intellectual Decline in Schizophrenia: Evidence from a Prospective Birth Cohort 28 Year Follow-up Study

Harvard University, Cambridge, Massachusetts, United States
Journal of Clinical and Experimental Neuropsychology (Impact Factor: 2.08). 03/2006; 28(2):225-42. DOI: 10.1080/13803390500360471
Source: PubMed


It is well established that IQ is lower among persons with schizophrenia than in the general population. However, it remains unclear if there is deterioration beyond a premorbid deficit. In order to assess the question of IQ deterioration, we assessed persons pre- and-post psychosis, comparing those who developed schizophrenia with those who did not. Twenty six patients with schizophrenia and 59 normal controls, evaluated at age 7 in the prospective, longitudinal, National Collaborative Perinatal Project (NCPP), were re-tested approximately 28 years later. We assessed change in an estimate of IQ based on the Vocabulary and Block Design tests from the Wechsler intelligence scales. Persons who later developed schizophrenia were significantly impaired on IQ compared to controls at age 7, especially on measures of attention. At age 35, persons with schizophrenia demonstrated significant impairment and deterioration on both IQ sub-tests compared to controls. Because impairment occurs by early childhood and subsequent deterioration occurs at an unknown period, designs with more frequent assessment of IQ through the premorbid, prodromal and early phases of illness are required to identify the key period of decline. Future research on this sample will evaluate the prospective roles of family history and perinatal complications on cognition, and assess the specificity of these findings.

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    • "None of the available studies reported the correlative analysis with certain PANSS items, although it is obvious that such items as ''conceptual disorganization'', ''difficulty in abstract thinking'' ''poor attention'' and ''disorientation'', can affect neurocognition and the effect of pharmacotherapy on the specific psychopathology can be closely related to the course of cognitive function. It is extremely important to highlight the possibility of a multidirectional course of various cognitive domains as some of the functions might deteriorate, while others may improve or do not express any changes [17] [58] [76] [90]. This approach might require a special analysis [86]. "
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    ABSTRACT: Background Cognitive disturbances are widely pronounced in schizophrenia and schizophrenia spectrum disorders. Whilst cognitive deficits are well established in the prodromal phase and are known to deteriorate at the onset of schizophrenia, there is a certain discrepancy of findings regarding the cognitive alterations over the course of the illness. Methods We bring together the results of the longitudinal studies identified through PubMed which have covered more than 3 years follow-up and to reflect on the potential factors, such as sample characteristics and stage of the illness which may contribute to the various trajectories of cognitive changes. Results A summary of recent findings comprising the changes of the cognitive functioning in schizophrenia patients along the longitudinal course of the illness is provided. The potential approaches for addressing cognition in the course of schizophrenia are discussed. Conclusions Given the existing controversies on the course of cognitive changes in schizophrenia, differentiated approaches specifically focusing on the peculiarities of the clinical features and changes in specific cognitive domains could shed light on the trajectories of cognitive deficits in schizophrenia and spectrum disorders.
    Full-text · Article · Nov 2015 · European Psychiatry
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    • "In previous studies, both education and IQ have been found to be significant protective factors and non-significant protective factors against psychotic symptoms (Wiles et al., 2006; Johns and van Os, 2001; Kelleher and Cannon, 2011). The association may also be explained by neurocognitive difficulties that are characteristic of psychosis, which may put individuals at greater risk of experiencing psychosis and discontinuing formal education (Niendam et al., 2003; Seidman et al., 2006). "
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    ABSTRACT: Recent epidemiological evidence suggests that sub-threshold psychotic experiences commonly occur in the general population. When these experiences persist over time, they may increase risk for psychotic disorder or lead to other clinical or functional impairments. The aims of this study were to distinguish the relative importance of sociodemographic factors and clinical factors, including characteristics of the psychotic experiences themselves, in determining the course of psychotic symptoms over time. Participants were drawn from the Collaborative Psychiatric Epidemiology Surveys. We tested for retrospectively-reported predictors of current psychotic experiences among individuals who reported lifetime psychotic experiences, with onset prior to the past year (n=921), using logistic regression. Persistence was primarily related to demographic variables, with lower odds associated with being married and having at least a college education. Individuals reporting prior to the past year auditory hallucinations were more likely to have persistent psychotic experiences than those reporting other types of psychotic experiences. Interventions aiming at strengthening family support and social skills may reduce the likelihood of persistence among individuals with psychotic experiences, thereby reducing risk for psychotic disorders and other related outcomes. Future studies should continue to identify predictors of persistence versus remission and further explore clinical services for those with persistent psychotic experiences.
    Full-text · Article · Sep 2015 · Schizophrenia Research
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    • "When cognitive deficits are first present and whether there is some stage of the illness during which they progress have been areas of intensive study.98,99 Cognitive deficits have been clearly demonstrated at the time of the FEP.89,98,100 "
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    ABSTRACT: Schizophrenia has historically been considered to be a deteriorating disease, a view reinforced by recent MRI findings of progressive brain tissue loss over the early years of illness. On the other hand, the notion that recovery from schizophrenia is possible is increasingly embraced by consumer and family groups. This review critically examines the evidence from longitudinal studies of (1) clinical outcomes, (2) MRI brain volumes, and (3) cognitive functioning. First, the evidence shows that although approximately 25% of people with schizophrenia have a poor long-term outcome, few of these show the incremental loss of function that is characteristic of neurodegenerative illnesses. Second, MRI studies demonstrate subtle developmental abnormalities at first onset of psychosis and then further decreases in brain tissue volumes; however, these latter decreases are explicable by the effects of antipsychotic medication, substance abuse, and other secondary factors. Third, while patients do show cognitive deficits compared with controls, cognitive functioning does not appear to deteriorate over time. The majority of people with schizophrenia have the potential to achieve long-term remission and functional recovery. The fact that some experience deterioration in functioning over time may reflect poor access, or adherence, to treatment, the effects of concurrent conditions, and social and financial impoverishment. Mental health professionals need to join with patients and their families in understanding that schizophrenia is not a malignant disease that inevitably deteriorates over time but rather one from which most people can achieve a substantial degree of recovery.
    Full-text · Article · Nov 2012 · Schizophrenia Bulletin
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