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

Department of Psychiatry at Massachusetts Mental Health Center, Harvard Medical School, Boston, USA.
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.
    European Psychiatry 11/2015; 30(8):1002-1010. DOI:10.1016/j.eurpsy.2015.08.005 · 3.44 Impact Factor
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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.
    Schizophrenia Research 09/2015; DOI:10.1016/j.schres.2015.08.039 · 3.92 Impact Factor
    • "While these findings suggest neurocognitive deterioration over the course of illness progression, determining the exact timing of the decline is relatively difficult. Cognitive decline could have occurred during the prodromal period, during the first episode, or after the onset of psychosis (Seidman et al. 2006; Bora, 2014). "
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    ABSTRACT: Although cognitive deficits in patients with schizophrenia are rooted early in development, the impact of psychosis on the course of cognitive functioning remains unclear. In this study a nested case-control design was used to examine the relationship between emerging psychosis and the course of cognition in individuals ascertained as clinical high-risk (CHR) who developed psychosis during the study (CHR + T). Fifteen CHR + T subjects were administered a neurocognitive battery at baseline and post-psychosis onset (8.04 months, s.d. = 10.26). CHR + T subjects were matched on a case-by-case basis on age, gender, and time to retest with a group of healthy comparison subjects (CNTL, n = 15) and two groups of CHR subjects that did not transition: (1) subjects matched on medication treatment (i.e. antipsychotics and antidepressants) at both baseline and retesting (Meds-matched CHR + NT, n = 15); (2) subjects unmedicated at both assessments (Meds-free CHR + NT, n = 15). At baseline, CHR + T subjects showed large global neurocognitive and intellectual impairments, along with specific impairments in processing speed, verbal memory, sustained attention, and executive function. These impairments persisted after psychosis onset and did not further deteriorate. In contrast, CHR + NT subjects demonstrated stable mild to no impairments in neurocognitive and intellectual performance, independent of medication treatment. Cognition appears to be impaired prior to the emergence of psychotic symptoms, with no further deterioration associated with the onset of psychosis. Cognitive deficits represent trait risk markers, as opposed to state markers of disease status and may therefore serve as possible predictors of schizophrenia prior to the onset of the full illness.
    Psychological Medicine 07/2015; -1:1-14. DOI:10.1017/S0033291715001233 · 5.94 Impact Factor
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