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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this paper, we describe the application of an automated method of calculating Gyrification Index (GI) - the Automated GI (A-GI) - to a total of 95 age-matched and sex-matched patients with mental retardation, schizophrenia, comorbid mental retardation and schizophrenia and controls. The results given by the A-GI program show that subjects with mental retardation possessed the lowest GI values in the pre-frontal lobes, with comorbid and schizophrenia groups being midway between this and the controls. The results showed no significant difference in pre-frontal gyrification between the schizophrenia and the comorbid groups. Although the four groups showed a similar pattern of (spatial) differences in terms of pre-frontal lobe volume, this did not solely account for the differences in A-GI. A significant negative correlation between GI and age was also observed across all four groups. These findings suggest that people with schizophrenia have reduced pre-frontal cortical folding regardless of whether or not they have low IQ. Previous studies in the same cohort have suggested that individuals comorbid for schizophrenia and mental retardation may in fact suffer from severe schizophrenia which has led to their low IQ. The pattern of differences observed in the current study supports this view.
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PMID:Pre-frontal lobe gyrification index in schizophrenia, mental retardation and comorbid groups: an automated study. 1725 4

Very low birth weight (VLBW) children are at high risk of perinatal white matter injury, which, when subtle, may not be seen using conventional magnetic resonance imaging. The relationship between clinical findings and fractional anisotropy (FA) measurements in white matter of adolescents born prematurely with VLBW was studied in 34 subjects (age = 15 years, birth weight </=1500 g) and 47 age-matched controls born at term, who were examined both clinically and with diffusion tensor imaging (DTI). Perceptual and cognitive functions were evaluated by visual motor integration (VMI) with supplementary tests and sub-tests from WISC-III, motor function by movement ABC and Grooved Pegboard test and psychiatric symptoms by the schedule for affective disorders and schizophrenia for school-age children semistructured interview, the Autism Spectrum Screening Questionnaire and attention deficit hyperactivity disorder (ADHD) rating scale IV. Overall functioning was scored on the children's global assessment scale. DTI scans were performed for calculation of FA maps and areas of significant differences in mean FA values between subjects and controls were compared with their clinical data. The VLBW children had reduced FA values in the internal and external capsule, corpus callosum and superior, middle superior and inferior fasciculus. Within this group of children, visual motor and visual perceptual deficits were associated with low FA values in the external capsule, posterior part of the internal capsule and in the inferior fasciculus. Children with low IQ had low FA values in the external capsule and inferior and middle superior fasciculus. Fine motor impairment was related to low FA values in the internal and external capsule and superior fasciculus. Eight VLBW children with inattention symptoms or a diagnosis of ADHD had significantly lower FA values in several areas. Mild social deficits correlated with reduced FA values in the external capsule and superior fasciculus. We conclude that DTI was able to detect differences in FA between VLBW adolescents and controls in several white matter areas at risk of periventricular leucomalacia in VLBW newborns. Our results show that low FA values in these areas were associated with perceptual, cognitive, motor and mental health impairments. These conclusions indicate that perinatal injury of white matter tracts persist with clinical significance in adolescence.
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PMID:Clinical findings and white matter abnormalities seen on diffusion tensor imaging in adolescents with very low birth weight. 1734 55

The increased schizophrenia risks for residents of cities with high levels of competition and for members of disadvantaged groups (for example migrants from low- and middle-income countries, people with low IQ, hearing impairments or a history of abuse) suggest that social factors are important for aetiology. Dopaminergic dysfunctioning is a key mechanism in pathogenesis. This editorial is a selective literature review to delineate a mechanism whereby social factors can disturb dopamine function in the brain. Experiments with rodents have shown that social defeat leads to dopaminergic hyperactivity and to behavioural sensitisation, whereby the animal displays an enhanced behavioural and dopamine response to dopamine agonists. Neuroreceptor imaging studies have demonstrated the same phenomena in patients with schizophrenia who had never received antipsychotics. In humans, the chronic experience of social defeat may lead to sensitisation (and/or increased baseline activity) of the mesolimbic dopamine system and thereby increase the risk for schizophrenia.
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PMID:Hypothesis: social defeat is a risk factor for schizophrenia? 1805 45

The aim of the study was to examine whether the postpsychotic decline in IQ during schizophrenia are due to a dementing process and psychopathological deterioration or this is a state independent premorbid impairment. The IQ score of 32 schizophrenic patients and 25 normal comparison subjects were evaluated three times during an average of 4,5 years, after short (mean 2,3 years) and long (mean 4,6) follow-up periods. The regression analysis was used to evaluate the association of clinical symptoms and IQ scores at the different period of time. The results were examined and related to changes of negative and positive symptoms of the illness. The schizophrenic group had low IQ score at baseline than the normal comparison subjects but showed comparable stability over time. The raw IQ score slightly increased in both groups in follow-up period. The regression analyses revealed that low IQ score especially in the block design (MT) and non-verbal reasoning (LPS3) subtests could be additional predictors for deterioration of negative symptoms. The IQ score of patients with schizophrenia appears to remain stable regardless of psychopathological decline, and even could be improved by learning and rehearsal.
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PMID:The relation between the general intellect of schizophrenic patients and psychopathological deterioration. 1935 23

Over the last decade, much progress has been made towards identifying risk factors for schizophrenia. It is now thought that many genes of small effect contribute towards risk of developing schizophrenia and some of these probably confer susceptibility to environmental factors. Large population-based studies, using record linkage, have investigated environmental risk factors and found that urbanization is an important factor. Other population-based studies have followed up birth cohorts and found evidence for abnormal neurodevelopment in those who subsequently developed schizophrenia. Meta-analyses have clarified the role of obstetric and perinatal complications especially hypoxia. Low IQ has emerged as a risk factor and suggests that cognitive factors are important in the etiology of psychosis. Social risk factors are now being investigated with some evidence that discrimination and isolation are significant. The role of recreational drug use is still unclear. Finally, evidence suggests that there is a continuum of psychosis both within the disorders that present clinically, but also in the general population.
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PMID:Risk factors for schizophrenia. 1981 Oct 30

Comparison of current and estimated premorbid IQ in schizophrenia suggests that there are subgroups with low IQ, deteriorated IQ (DIQ), or preserved IQ and that this is established by psychosis onset. There are no controlled studies examining the trajectory of these IQ subgroups longitudinally or their relationship with clinical and social outcomes. Of 129 individuals with first-episode schizophrenia or schizoaffective disorder, 25% showed stable low IQ, 31% showed stable IQ in the average/high range, and 44% demonstrated intellectual deterioration by 10 points or more. Patients in the low and deteriorated groups were equally impaired on tests of memory and executive function compared with the preserved average/high-IQ group and controls and showed more negative and disorganization symptoms than the preserved average/high-IQ group. Sixty patients and 27 controls were assessed again 1 and 3 years later. There was no evidence that those with IQ deterioration at baseline continued on a declining cognitive trajectory or that those with preserved average/high IQ experienced subsequent IQ decline. The low IQ group showed no change in IQ, whereas both the DIQ and the preserved IQ groups improved. However, the rate of improvement of these 2 subgroups was no greater than that of the healthy controls, suggesting that this reflected practice effects. Both the low and the deteriorated groups had longer index admissions, more core negative symptoms, and worse occupational outcomes at 3 years. These data suggest that following psychosis onset, IQ is stable and that it is IQ at psychosis onset rather than premorbid IQ predicts a more severe illness.
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PMID:IQ trajectory, cognitive reserve, and clinical outcome following a first episode of psychosis: a 3-year longitudinal study. 1993 12

Phenotypic heterogeneity within patients and controls may explain why the genetic variants contributing to schizophrenia risk explain only a fraction of the heritability. The aim of this study is to investigate quantitative and qualitative differences in psychosis symptoms in a sample including psychosis patients, their relatives, and community controls. We combined factor analysis and latent class analysis to analyze variation in Comprehensive Assessment of Symptoms and History lifetime-rated symptoms in 4286 subjects. The Wechsler Adult Intelligence Scale-Intelligence Quotient (N = 2663) and the Camberwell Assessment of Need rating scale (N = 625) were assessed in a subsample. Variation in 5 continuous dimensions (disorganization, positive, negative, mania, and depression) was accounted for by the presence of 7 homogeneous classes (Kraepelinian schizophrenia, affective psychosis, manic-depression, deficit nonpsychosis, depression, healthy, and no symptoms). Eighty-five percent of the schizophrenia patients was assigned to the Kraepelinian schizophrenia class (characterized by high scores on the 5 dimensions, low IQ, and poor outcome) while 15% was assigned to the affective psychosis class (relatively low disorganization and negative scores, normal IQ, and good outcome). In bipolar patients (91% bipolar I), 41% was assigned to the Kraepelinian schizophrenia class, 44% to the affective psychosis class, and 10% to the manic-depression class. Latent class membership was associated with intelligence in psychosis patients and in their relatives but not in community controls. In conclusion, symptom heterogeneity is more pronounced in bipolar disorder compared with schizophrenia. Reducing phenotypic heterogeneity within psychosis patients and controls may facilitate etiological research.
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PMID:Kraepelin was right: a latent class analysis of symptom dimensions in patients and controls. 2086 20

Although most studies find low socioeconomic status (SES) to be associated with prevalence of schizophrenia, incidence studies do not generally support this, and some even report an inverse association. The objective of the current historical prospective study was to examine the relationship between SES, cognitive functioning, and risk of hospitalization for schizophrenia in a population-based sample of Israeli adolescents. Subjects were 811 487 adolescents, assessed by the Israeli military draft board for socio-demographic factors and cognitive functioning. Data on later hospitalization for schizophrenia were obtained from a population-based hospitalization registry. Findings indicated that when simply examining SES and schizophrenia, lower SES was associated with greater risk of hospitalization for schizophrenia (Hazard Ratio [HR] = 1.193, 95% CI = 1.091-1.303). When dividing the cohort into low, average, and high cognitive functioning, SES did not influence the risk for schizophrenia among individuals with high and average cognitive functioning, whereas among individuals with low cognitive functioning, high SES was found to slightly increase the risk for schizophrenia (HR = 1.21, 95% CI = 1.03-1.42). One possible explanation for this finding might be that among individuals from low socioeconomic backgrounds, low IQ may reflect decreased opportunities related to SES, whereas among individuals from high SES backgrounds, low IQ might reflect risk for later psychopathology.
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PMID:The relationship between risk of hospitalization for schizophrenia, SES, and cognitive functioning. 2160 6

Estimates of pre-morbid IQ are widely used to measure the trajectory of cognitive function and decline in people with schizophrenia. This study examined the usefulness of two indices of decline to identify cognitive subtypes in first episode psychosis, and to determine the specificity of non-IQ neuropsychological impairments in this population. Neuropsychological data were collected from 118 first episode psychosis patients and compared to 118 epidemiologically matched controls. The National Adult Reading Test (NART) and the Information subtest of the WAIS-III were compared as indicators of crystallised intelligence or 'pre-morbid IQ'. Measurement of NART minus current full scale IQ (FSIQ) (where 10 points discrepancy is the decline criterion) did not reveal a large group of individuals with 'deteriorating' IQ patterns. Using the Information subtest and the same decline criteria, a 'deteriorating' patient group emerged (36%) but was matched by a larger 'deteriorating' control group (45%). The 'deteriorating' patient group performed at a low IQ level for tasks that loaded highly on performance ability but a relatively high level for tasks measuring verbal skills. Verbal memory discriminated patients from controls better than IQ. Compared to controls, patients showed large selective impairments of verbal episodic memory (effect size, d=1.4) These data suggest that in first episode populations, caution should be exercised in inferring deterioration of IQ from discrepancies between reading-based and other IQ tests. Rather, sub-groups of patients and controls do show greater verbal aptitude in comparison to performance skills. Memory is generally impaired in first episode patients regardless of IQ.
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PMID:Is deterioration of IQ a feature of first episode psychosis and how can we measure it? 2234 99

ZNF804A gene polymorphism rs1344706 has been suggested as the most compelling case of a candidate gene for schizophrenia by a genome-wide association study and several replication studies. The current study of 570 schizophrenia patients and 448 controls again found significantly different genotype frequencies of rs1344706 between patients and controls. More important, we found that this association was modulated by IQ, with a stronger association among individuals with relatively high IQ, which replicated results of Walters et al, 2010. We further examined whether this IQ-modulated association also existed between the SNP and the intermediate phenotypes (working memory and executive functions) of schizophrenia. Data were available from an N-back task (366 patients and 414 controls) and the attention network task (361 patients and 416 controls). We found that the SNP and IQ had significant interaction effects on the intermediate phenotypes for patients, but not for controls. The disease risk allele was associated with poorer cognitive function in patients with high IQ, but better cognitive function in patients with low IQ. Together, these results indicated that IQ may modulate the role of rs1344706 in the etiology of both schizophrenia and its cognitive impairments, and pointed to the necessity of considering general cognitive function as indexed by IQ in the future studies of genetic bases of schizophrenia.
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PMID:Evidence of IQ-modulated association between ZNF804A gene polymorphism and cognitive function in schizophrenia patients. 2237 44


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