Epidemiological and clinical correlates of familial and sporadic schizophrenia

Evidence for increased DNA damage repair in the postmortem brain of the high stress-response group of schizophrenia

Background

Schizophrenia (SZ) is a disorder diagnosed by specific symptoms and duration and is highly heterogeneous, clinically and pathologically. Although there are an increasing number of studies on the association between genetic and environmental factors in the development of SZ, the actual distribution of the population with different levels of influence of these factors has not yet been fully elucidated. In this study, we focused on stress as an environmental factor and stratified SZ based on the expression levels of stress-responsive molecules in the postmortem prefrontal cortex.

Methods

We selected the following stress-responsive molecules: interleukin (IL) -1β, IL-6, IL-10, tumor necrosis factor-α, interferon-γ, glucocorticoid receptor, brain-derived neurotrophic factor, synaptophysin, S100 calcium-binding protein B, superoxide dismutase, postsynaptic density protein 95, synuclein, apolipoprotein A1 (ApoA1), ApoA2, and solute carrier family 6 member 4. We performed RNA sequencing in the prefrontal gray matter of 25 SZ cases and 21 healthy controls and conducted a hierarchical cluster analysis of SZ based on the gene expression levels of stress-responsive molecules, which yielded two clusters. After assessing the validity of the clusters, they were designated as the high stress-response SZ group and the low stress-response SZ group, respectively. Ingenuity Pathway Analysis of differentially expressed genes (DEGs) between clusters was performed, and Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was conducted on four cases each in the high and low stress-response SZ groups to validate DNA damage.

Results

We found higher prevalence of family history of SZ in the low stress-response SZ group (0/3 vs. 5/4, p = 0.04). Pathway analysis of DEGs between clusters showed the highest enrichment for DNA double-strand break repair. TUNEL staining showed a trend toward a lower percentage of TUNEL-positive cells in the high stress-response SZ group.

Conclusion

Our results suggest that there are subgroups of SZ with different degrees of stress impact. Furthermore, the pathophysiology of these subgroups may be associated with DNA damage repair. These results provide new insights into the interactions and heterogeneity between genetic and environmental factors.

Clinical characteristics of familial schizophrenia

INTRODUCTION

A family history of psychiatric disorders is one of the strongest risk factors for schizophrenia. The characteristics of patients with a family history of psychiatric disorders have not been systematically evaluated.

METHODS

This multicenter study (26 centers, 2425 cases) was performed in a Chinese population to examine the sociodemographic and clinical characteristics of schizophrenia patients with a family history of psychotic disorders in comparison with those of patients with sporadic schizophrenia.

RESULTS

Nineteen percent of patients had a family history of mental disease. Multiple logistic regression analysis revealed that ≥4 hospitalizations (OR = 1.78, P = .004), tobacco dependence (OR = 1.48, P = .006), alcohol dependence (OR = 1.74, P = .013), and physical illness (OR = 1.89, P = .001) were independently and significantly associated with a family history of mental disease.

CONCLUSION

Patients with a family history of mental disorders present different demographics and clinical features than patients without a family history of psychiatric disorders.

Terminology and assessment tools of psychosis: A systematic narrative review

AIM

Phenomena within the psychosis continuum that varies in frequency/duration/intensity have been increasingly identified. Different terms describe these phenomena, however there is no standardization within the terminology. This review evaluated the definitions and assessment tools of seven terms - (i) 'psychotic experiences'; (ii) 'psychotic-like experiences'; (iii) 'psychotic-like symptoms'; (iv) 'attenuated psychotic symptoms'; (v) 'prodromal psychotic symptoms'; (vi) 'psychotic symptomatology'; and (vii) 'psychotic symptoms'.

METHODS

EMBASE, MEDLINE, and CINAHL were searched during February-March 2019. Inclusion criteria included 1989-2019, full text, human, and English. Papers with no explicit definition or assessment tool, duplicates, conference abstracts, systematic reviews, meta-analyses, or no access were excluded.

RESULTS

A total of 2238 papers were identified and of these, 627 were included. Definitions and assessment tools varied, but some trends were found. Psychotic experiences and psychotic-like experiences were transient and mild, found in the general population and those at-risk. Psychotic-like symptoms were subthreshold and among at-risk populations and non-psychotic mental disorders. Attenuated psychotic symptoms were subthreshold but associated with distress, risk, and help-seeking. Prodromal psychotic symptoms referred to the prodrome of psychotic disorders. Psychotic symptomatology included delusions and hallucinations within psychotic disorders. Psychotic symptoms was the broadest term, encompassing a range of populations but most commonly involving hallucinations, delusions, thought disorder, and disorganization.

DISCUSSION

A model for conceptualizing the required terms is proposed and future directions needed to advance this field of research are discussed.

Performance of Verbal Fluency as an Endophenotype in Patients with Familial versus Sporadic Schizophrenia and Their Parents

What’s the neurocognitive deficit as an endophenotype to familial schizophrenia? Here, we investigate the neurocognitive endophenotype in first-episode patients with familial schizophrenia (FS) and sporadic schizophrenia (SS), and their parents. 98 FS patients and their 105 parents; 190 SS patients and their 207 parents; 195 controls matched with patients, and 190 controls matched with the patients’ parents, were assessed with the short version of the Wechsler Adult Intelligence Scale-Revised in China (WAIS-RC), the immediate and delayed logical memory tests from the Wechsler Memory Scale-Revised in China (WMS-RC), the Verbal Fluency Test (VFT), the Trail Making Test Parts A and B-Modified (TMA, TMB-M), and the Modified Wisconsin Card Sorting Test (WCST-M). The results showed that with age, gender, and education as covariates, after controlling for false discovery rates, the FS group and their parent group performed worse than the SS group and their parent group on VFT. No significant differences were found for other neurocognitive tests between the FS and SS patient groups, and their respective parent groups. Our findings suggest the patients with familial and sporadic schizophrenia and their respective parent groups may have a different genetic predisposition in relation to a cognitive endophenotype.

Distinct disruptions of resting-state functional brain networks in familial and sporadic schizophrenia

Clinical and brain structural differences have been reported between patients with familial and sporadic schizophrenia; however, little is known about the brain functional differences between the two subtypes of schizophrenia. Twenty-six patients with familial schizophrenia (PFS), 26 patients with sporadic schizophrenia (PSS) and 26 healthy controls (HC) underwent a resting-state functional magnetic resonance imaging. The whole-brain functional network was constructed and analyzed using graph theoretical approaches. Topological properties (including global, nodal and edge measures) were compared among the three groups. We found that PFS, PSS and HC exhibited common small-world architecture of the functional brain networks. However, at a global level, only PFS showed significantly lower normalized clustering coefficient, small-worldness, and local efficiency, indicating a randomization shift of their brain networks. At a regional level, PFS and PSS disrupted different neural circuits, consisting of abnormal nodes (increased or decreased nodal centrality) and edges (decreased functional connectivity strength), which were widely distributed throughout the entire brain. Furthermore, some of these altered network measures were significantly correlated with severity of psychotic symptoms. These results suggest that familial and sporadic schizophrenia had segregated disruptions in the topological organization of the intrinsic functional brain network, which may be due to different etiological contributions.

Familial liability to schizophrenia and mood disorders and cognitive impairment in psychosis

Schizophrenia and other psychoses are complex disorders with high rates of cognitive impairment and a considerable degree of genetic and environmental influence on its etiology. Whether cognitive impairment is related to dimensional scores of familial liability is still matter of debate. We conducted a cross-sectional study including 169 patients with psychotic disorders and 26 healthy controls. Attention, memory and executive functions were assessed, and familial loading scores for schizophrenia and mood disorders were calculated. The relationships between familial liability and neuropsychological performance were examined with Spearman׳s correlation coefficients. In addition, patients were classified into three groups by family loading tertiles, and comparisons were performed between the patients in the top and bottom tertiles. Low familial loading scores for schizophrenia showed a significant association with poor executive functioning and delayed visual memory. And these results were also achieved when the subset of psychotic patients in the two extreme tertiles of family loadings of schizophrenia and mood disorders were compared. Low familial liability to schizophrenia seems to be a contributing factor for the severity of cognitive impairment in patients with a broad putative schizophrenia spectrum diagnosis.

The association between intelligence scores and family history of psychiatric disorder in schizophrenia patients, their siblings and healthy controls

Background

The degree of intellectual impairment in schizophrenia patients and their relatives has been suggested to be associated with the degree of familial loading for schizophrenia. Since other psychiatric disorders are also more present in relatives of schizophrenia patients, the definition of family history should be broadened. The association between family history for psychiatric disorder and intelligence scores was investigated in patients with non-affective psychosis, their unaffected siblings and controls.

Methods

A sample of 712 schizophrenia proband families (696 patients and 766 siblings) and 427 healthy control families (517 subjects) participated in this study. Family history of psychiatric disorder was determined while excluding the data of the participating schizophrenia patient. A dichotomous division was made between families with no first- or second degree relative with psychiatric disorder and families with one or more affected relatives. Total intelligence scores were estimated by admission of the short form of the Wechsler Adult Intelligence Scale III.

Results

A significant interaction was found between family history of psychiatric disorder and clinical status (F(2,1086.87)= 4.17; p=.016). Patients with a positive family history of psychiatric disorder obtained higher intelligence scores compared to patients with no family history (mean IQ scores are 95.52 and 92.72) with an opposite effect in controls (mean IQ scores are 108.71 and 111.19). No significant difference was found between siblings of schizophrenia patients with or without a positive family history (mean IQ scores are 102.98 and 103.24).

Conclusion

In patients with schizophrenia, a negative family history of psychiatric disorder was associated with relatively low IQ suggesting that the etiology in these patients may involve environmental or genetic factors which are unique to the patient and are not observed in other relatives. Possible factors include severe environmental stressors containing premature birth or brain injury and genetic factors (e.g de novo Copy Number Variants).

The impact of a family history of psychosis on age-at-onset and positive and negative symptoms of schizophrenia: a meta-analysis

The results of research on the relation of family history (FH) of psychosis with clinical presentation in schizophrenia have been mixed. To date, there have been no comprehensive reviews that have examined this body of research. The current review quantitatively evaluates research on the relation of FH with two aspects of schizophrenia, age-at-onset and symptom presentation. Studies investigating the influence of a FH on age-at-onset (N=15 studies), age-at-onset and sex (N=12 studies), and/or positive (N=11 studies) and negative symptoms (N=12 studies) in patients with schizophrenia were included in the meta-analyses. Results showed that FH has a small but significant impact on age-at-onset as well as negative symptoms. Of most interest was the finding that sex differences in age-at-onset are not observed in samples with a FH. Furthermore, there was a significant interaction between FH and sex with respect to negative symptoms. The findings of the current review are discussed in light of the diathesis-stress model. Theoretical assumptions and empirical research are reviewed to support the notion that FH influences susceptibility and presentation through similar mechanisms. Implications of the current findings, limitations of the review, and directions for future research are highlighted.

The significance of family history in first-episode schizophrenia spectrum disorder

There have been inconsistent findings regarding the significance of family history of schizophrenia spectrum disorders in relation to presentation and course of illness. There has been little research relevant to this issue from first-episode patients. We examined the differences in premorbid adjustment, symptoms, and intellectual functioning between 28 first-episode schizophrenia spectrum patients with a history of such illness in first degree relatives and 28 matched patients without such a family history. The results indicate that whereas the 2 groups did not differ in presenting symptoms, those with a positive family history showed poorer intellectual functioning and less reduction in symptoms at 2 and 3 year follow-up and greater likelihood of abnormal electroencephalogram findings. The findings provide evidence that presence of a positive family history in first-episode patients is associated with a more pernicious form of illness.

The relationship between syndromes of the psychotic illness and familial liability to schizophrenia and major mood disorders

BACKGROUND

Previous studies examining the relationship between psychopathological syndromes of the psychotic illness and familial liability to schizophrenia and mood disorders have obtained inconclusive results. The aim of this study is to further examine this issue by analyzing a large sample of psychotic probands and their first-degree relatives.

METHODS

The sample was composed of 660 psychotic inpatients and their 2987 first-degree relatives. Probands were assessed for index episode and lifetime symptoms, while relatives were assessed for lifetime diagnosis of schizophrenia and major mood disorders. Associations between factor-analysis derived syndromes in probands and familial loading for schizophrenia and major mood disorders were tested.

RESULTS

Familial morbid risk of schizophrenia was predicted by the negative syndrome in probands and familial morbid risk of mood disorders was predicted by mania, depression and catatonia syndromes in probands. This association pattern was relatively independent of type of symptom rating (index episode or lifetime) and probands' diagnosis of schizophrenia or major mood disorder. Familial loading for schizophrenia and mood disorders cut-across the DSM-IV categories of psychotic disorders in probands.

CONCLUSION

From a dimensional perspective, the negative syndrome is related to familial liability to develop schizophrenia. Mania, depression and catatonia syndromes are related to the familial liability to develop major mood disorders. Categories of psychotic disorders are on a continuum of familial liability to schizophrenia and major mood disorders.

More severe sustained attention deficits in nonpsychotic siblings of multiplex schizophrenia families than in those of simplex ones

Sustained attention deficits measured by the Continuous Performance Test (CPT) have been proposed as an endophenotype of schizophrenia. However, little is known about whether sustained attention deficits in first-degree relatives of schizophrenic patients are associated with familial loading for schizophrenia. We examined 107 parents and 84 siblings of simplex schizophrenia families as well as 72 parents and 56 siblings of multiplex schizophrenia families, all nonpsychotic, using the Diagnostic Interview for Genetic Studies and two sessions of the CPT (undegraded and degraded). The effect of perceptual load was assessed using the residual of the regression of the degraded score on the undegraded one. Statistical models that can adjust for familial correlations were used to compare the CPT performance of relatives between the two types of families. Siblings from multiplex families exhibited worse performance on the degraded CPT and less proficiency in processing the perceptual load than those from simplex families. No such difference was observed for the parents on either CPT version. We concluded that sustained attention along with perceptual load processing is more impaired in the siblings of schizophrenic patients with high familial loading and that this finding might be useful for future genetic dissection of schizophrenia.

Subtyping schizophrenia: implications for genetic research

Phenotypic variability and likely extensive genetic heterogeneity have been confounding the search for the causes of schizophrenia since the inception of the diagnostic category. The inconsistent results of genetic linkage and association studies using the diagnostic category as the sole schizophrenia phenotype suggest that the current broad concept of schizophrenia does not demarcate a homogeneous disease entity. Approaches involving subtyping and stratification by covariates to reduce heterogeneity have been successful in the genetic study of other complex disorders, but rarely applied in schizophrenia research. This article reviews past and present attempts at delineating schizophrenia subtypes based on clinical features, statistically derived measures, putative genetic indicators, and intermediate phenotypes, highlighting the potential utility of multidomain neurocognitive endophenotypes.

The impact of family experience on the duration of untreated psychosis (DUP) in Hong Kong

BACKGROUND

Previous family experience of psychotic illness may play an important role in whether and when a patient seeks help in first-episode psychosis. This study investigated the relationship between family experience of psychosis and the duration of untreated psychosis in a prospective sample of first-episode psychosis patients in Hong Kong. We also studied the effects of pre-morbid adjustment, educational level, living alone, and mode of onset as potential determinants of the duration of untreated psychosis (DUP).

METHODS

A total of 131 first-episode psychosis patients in Hong Kong were recruited in a study of the DUP and related factors. The Interview for the Retrospective Assessment of the Onset of Schizophrenia (IRAOS) was used to measure the DUP and to provide a structured assessment of family history, educational level, household arrangement, and mode of onset.

RESULTS

Previous family experience of psychiatric illness (the presence of another family member who has been receiving psychiatric treatment) and an acute mode of onset were significant predictors of a shorter DUP. Educational level had a modest effect on its own, but was not significant in the binary logistic regression model. Living alone had a moderate effect size, but was non-significant, possibly because of the small proportion of single-person households in the sample. The symptom profile, pre-morbid adjustment, and other demographic factors were not significantly related to the DUP.

CONCLUSION

In addition to the mode of onset, previous family experience plays an important role in the presentation of early psychosis. Educational efforts that target the family should be an important part of any strategy for the early detection of psychosis.

Explaining variation in the premorbid adjustment of schizophrenia patients: the role of season of birth and family history

Several studies have shown that patients with schizophrenia are more likely to be born in the winter and early spring than at any other time of the year. Furthermore, some studies have reported that winter-born patients differ from non-winter-born patients in terms of risk factors, symptoms, sensory abnormalities and brain morphology. Associations between season of birth and premorbid adjustment (PMA), however, are still unclear.

OBJECTIVE

The main purpose of this study was to determine whether winter-born and non-winter-born schizophrenia patients differ in terms of PMA and to examine how family history of schizophrenia-spectrum disorders may influence the association.

METHOD

Data on four PMA dimensions (attention, internalizing, externalizing and social problems) and family history were gathered from 37 schizophrenia patients (26 males and 11 females) and their mothers.

RESULTS

Non-winter-birth and a positive family history of schizophrenia-spectrum disorders were associated with worse PMA. Results suggest that, although no significant interaction was found, season of birth and family history appear to work together in explaining distinct dimensions of PMA.

No association between season of birth of patients with schizophrenia and risk of schizophrenia among their siblings

Previous studies on the relationship between the season of birth of patients with schizophrenia and the risk of schizophrenia among their siblings have yielded contradictory results. We investigated whether proband's month of birth affects siblings' risk of developing schizophrenia. We used the Finnish Hospital Discharge Register to identify all patients born in Finland from 1950 to 1976 who had been hospitalized because of schizophrenia at least once between 1969 and 1995. Their siblings were identified from the National Population Register, and data on siblings were linked to the Hospital Discharge Register to obtain information on any hospitalizations. We used logistic regression to investigate a sibling's probability of developing schizophrenia, defining the proband initially as the first sibling in calendar time to develop schizophrenia, then as the affected sibling with lowest onset age. Within-family dependence was taken into account by using robust standard error estimates. Neither models found any association between proband's month of birth and siblings' odds of developing schizophrenia. Our results support those previous studies that found no association between proband's month of birth and family history of schizophrenia, and suggest that the winter-spring excess of births among patients with schizophrenia is not caused by any genetic or environmental risk factor that operates independently of other risk factors.

Specific executive/attentional deficits in patients with schizophrenia or bipolar disorder who have a positive family history of psychosis

Neurocognitive impairments are well documented in patients with schizophrenia and their healthy first-degree biological relatives. Less is known about neuropsychological performance in bipolar disorders, but some studies indicate that, compared to schizophrenia, bipolar disorder displays a similar profile pattern with less severe deficits. The genetic and environmental contributions to the development of neurocognitive deficits are also unclear. This study explored the effect of a family history (FH) of psychotic disorders in first-degree relatives on a variety of cognitive domains (abstraction and flexibility, verbal fluency, verbal memory, motor activity and visual-motor processing/attention) in 30 patients with schizophrenia, and 24 type I bipolar patients. After adjusting the results for age, gender, education level and pre-morbid intelligence, patients with schizophrenia or bipolar disorder with positive FH (n=18) performed significantly worse than patients with negative FH (n=36) on the visual-motor processing/attention domain. These findings were independent of the specific diagnosis. Moreover, when logistic regression analysis was performed, poor Digit Symbol performance was the only predictor of belonging to the positive FH group. Our results are compatible with the existence of some common genetic factors between the illnesses, as well as the involvement of identical, or at least similar, disordered brain systems in both disorders. These findings are discussed within the context of the continuum model of psychosis.

Preventing schizophrenia and psychotic behaviour: definitions and methodological issues

Although schizophrenia onset usually occurs in late adolescence or early adulthood, much research shows that its seeds are planted early in life and that eventual onset occurs at the end of a neurodevelopmental process leading to aberrant brain functioning. This idea, along with the fact that current therapies are far from fully effective, suggests that preventive treatments may be needed to achieve an ideal outcome for schizophrenia patients and those predisposed to the disorder. In this article, we review the methodological challenges that must be overcome before effective preventive interventions can be created. Prevention studies will need to define the target population. This requires the identification of risk factors that will be useful in selecting at-risk people for preventive treatment. We review currently identified risk factors for schizophrenia: genes, psychosocial factors, pregnancy and delivery complications, and viruses. We also review 3 different types of prevention programs: universal, indicated, and selective. For schizophrenia, we distinguish prevention programs that target prodromal cases and those that target the disorder's premorbid precursors. Although those targeting prodromal cases provide a useful framework for early treatment of the disorder, studies of premorbid individuals are needed to design a truly preventive treatment.

[Introduction to genetic psychiatry: progress in uncovering genetic susceptibility to psychiatric disorders]

The recent progress in human genetics suggests major benefits in clinical practice, including psychiatry. This article introduces the research methodology used in psychiatric genetics and explains how it is applied, for a better understanding of the challenges facing psychiatric genetics and the strategies being used to overcome them. We will review the evidence of genetic factors in psychiatric disorder etiology as well as the specificity or non-specificity of their expression. We will discuss problems associated with the approximate nature of diagnostic methods, the incomplete penetrance and the genetic heterogeneity of psychiatric disorders, the presence of phenocopies and our uncertainty concerning the mode of inheritance of psychiatric disorders. Finally, we will provide an overview of the most promising results and set out priorities for future studies.

Paternal factors and schizophrenia risk: de novo mutations and imprinting

There is a strong genetic component for schizophrenia risk, but it is unclear how the illness is maintained in the population given the significantly reduced fertility of those with the disorder. One possibility is that new mutations occur in schizophrenia vulnerability genes. If so, then those with schizophrenia may have older fathers, because advancing paternal age is the major source of new mutations in humans. This review describes several neurodevelopmental disorders that have been associated with de novo mutations in the paternal germ line and reviews data linking increased schizophrenia risk with older fathers. Several genetic mechanisms that could explain this association are proposed, including paternal germ line mutations, trinucleotide repeat expansions, and alterations in genetic imprinting in one or several genes involved in neurodevelopment. Animal models may be useful in exploring these and other explanations for the paternal age effect and they may provide a novel approach for gene identification. Finally, it is proposed that environmental exposures of the father, as well as those of the mother and developing fetus, may be relevant to the etiology of schizophrenia.

Neurological signs and psychomotor performance in patients with schizophrenia, their relatives and healthy controls

Schizophrenic patients (DSM-III-R) were consecutively recruited and 39 were included. Twenty-one were first-episode and 18 were chronic schizophrenic patients. Thirty of the patients were on neuroleptic medication. Thirty-three parents were included, of whom nine were classified as 'family history positive' and 22 as 'family history negative' of a disposition to psychosis. Fifty-five healthy controls volunteered. The subjects were investigated according to a protocol divided into neurological signs and psychomotor performance (finger-tapping rate, Purdue pegboard test, pronation-supination test, gait and hand-grasp strength). Seventy-eight percent of the patients and 7% of the controls were classified as globally aberrant in signs. The patients and their parents, classified as 'family history positive', exhibited a similar laterality pattern in a finger-tapping test improving performance with the preferred hand, significantly different from the performance of the 'family history negative' parents and normal subjects. Duration of illness, neuroleptic medication and negative symptoms were not related to the occurrence of neurological signs and psychomotor performance. These findings indicate that neurological aberrations are present at the onset of illness and that hereditary factors are associated with motor laterality.

The relationship between smooth pursuit eye movements and tardive dyskinesia in schizophrenia

OBJECTIVE

To examine the relationship between smooth pursuit eye movements and tardive dyskinesia (TD) in schizophrenia.

METHODS

Forty schizophrenic patients with TD and 25 non-TD patients had smooth pursuit eye movements tested with infrared oculography. In addition to the diagnosis of TD (present or absent), each patient had ratings of severity of TD.

RESULTS

There was no significant or strong association between TD and poor smooth pursuit eye movements.

CONCLUSION

The results stand in contrast to those of several previous studies, which were based on limited methodology. However, this study was not able to exclude definitively the possibility that TD is associated with poor smooth pursuit, perhaps with a small to moderate effect. Furthermore, these conclusions are limited to simple eye tracking protocols in which distractions are minimized. The question of whether or not TD is associated with poor smooth pursuit in schizophrenia needs to be resurrected.

Seasonality of births in schizophrenia and bipolar disorder: a review of the literature

More than 250 studies, covering 29 Northern and five Southern Hemisphere countries, have been published on the birth seasonality of individuals who develop schizophrenia and/or bipolar disorder. Despite methodological problems, the studies are remarkably consistent in showing a 5-8% winter-spring excess of births for both schizophrenia and mania/bipolar disorder. This seasonal birth excess is also found in schizoaffective disorder (December-March), major depression (March-May), and autism (March) but not in other psychiatric conditions with the possible exceptions of eating disorders and antisocial personality disorder. The seasonal birth pattern also may shift over time. Attempts to correlate the seasonal birth excess with specific features of schizophrenia suggest that winter-spring births are probably related to urban births and to a negative family history. Possible correlations include lesser severity of illness and neurophysiological measures. There appears to be no correlation with gender, social class, race, measurable pregnancy and birth complications, clinical subtypes, or neurological, neuropsychological, or neuroimaging measures. Virtually no correlation studies have been done for bipolar disorder. Regarding the cause of the birth seasonality, statistical artifact and parental procreational habits are unlikely explanations. Seasonal effects of genes, subtle pregnancy and birth complications, light and internal chemistry, toxins, nutrition, temperature/weather, and infectious agents or a combination of these are all viable possibilities.

Age of onset in familial and sporadic schizophrenia

We have studied the gender and family history differences with regard to age of onset of schizophrenia. These differences have often been viewed as an important clue to the aetiology of the illness. Patients from three centres in Europe and Canada were included in the study. A sample of 1089 subjects was categorized according to the subject's sex, family history of schizophrenia, and the centre. The principal statistical method was analysis of variance. Patients with no family history of schizophrenia had a consistently higher average age of onset. This effect was seen in both male and female subjects across all three groups. These results support the relationship between familial risk and early onset, but no interaction of gender and family history was found.

Accuracies and inaccuracies of the family history method: a multivariate approach

This paper reports on 1459 first-degree relatives of probands with schizophrenia or affective illness and matched community controls. We sought (i) to validate psychiatric diagnoses obtained by family history (FH) against those obtained by a best estimate (BE) procedure based on personal interview and (ii) to explore the factors influencing the accuracy of the FH report. We found relatively poor agreement between the FH and BE diagnoses, and the disagreements were influenced by numerous factors, including gender, psychiatric status of the informant or proband's diagnosis. When validated against a BE diagnosis, the overall accuracy of the FH method is relatively poor, and is furthermore subject to several biases. Therefore, substituting the FH method for BE diagnosis may be an important source of error in the investigation of familial/genetic factors in psychiatric disorders.

No difference found between winter- and non-winter-born schizophrenic cases

The distinction between winter-born (WBS) and non-winter born (NWBS) schizophrenic cases has been proposed as a strategy to identify distinct etiologic subtypes within schizophrenia, the WBS subgroup being a predominantly environmental subtype. The goal of this paper is to empirically test the validity of this strategy by comparing WBS and NWBS groups on a broad array of clinical and biological variables. DSM-III-R schizophrenic, schizoaffective and schizophreniform subjects were comprehensively assessed using (i) the Comprehensive Assessment of Symptoms and History; (ii) a comprehensive neurological exam; (iii) a neuropsychological battery, including IQ and the Continuous Performance Test and (iv) an MRI scanning. The patients were divided into WBS and NWBS, using five alternative sets of definitions of winter birth. These comparisons yielded no differences between the groups on any of the 23 variables. The results suggest that the distinction between winter-born and non-winter-born cases has very limited power to identify distinct schizophrenic subtypes, and that better delineation of the correlates of environmental risk factors in schizophrenia will require a better identification of these factors.

The estrogen connection: the etiological relationship between diabetes, cancer, rheumatoid arthritis and psychiatric disorders

For some considerable time, there has been a growing awareness that defective essential fatty acid metabolism plays a causal role in the pathogenesis of both schizophrenia and non-insulin-dependent diabetes mellitus (NIDDM) but the influence of defective essential fatty acid metabolism in the pathogenesis of rheumatoid arthritis and cancer is less well appreciated. An EFA deficiency, or defective EFA metabolism, negatively influences prostaglandin synthesis and glucose regulation and transport. Moreover, defective EFA metabolism negatively influences estrogen availability which contributes to the observed gender bias some of these illnesses manifest. While fluctuations of estrogen are known to contribute to the pathogenesis of these conditions, so also do fluctuations of IGF-II and there is some suggestion that IGF-II and insulin may well be inversely regulated. In addition, insulin-dependent diabetes mellitus (IDDM), rheumatoid arthritis, and schizophrenia are thought to be autoimmune disorders, while cancer is associated with immune system failure. Consequently, this paper aims to examine the pathophysiological similarities and differences between mental illness, diabetes, rheumatoid arthritis and cancer in respect of which the causal relationship that obtains between essential fatty acids, estrogen, IGF-II, glucose regulation and autoimmunity will be addressed.

Magnetic resonance imaging in familial versus sporadic cases of schizophrenia

Magnetic resonance imaging findings were compared in 22 familial and 29 sporadic cases with DSM-III-R diagnoses of schizophrenia, schizoaffective, or schizophreniform disorders. Volumetric measurements were used to assess the size of brain structures, including the cranium, cerebrum, lateral ventricles, temporal horns, third ventricle, lenticular nuclei, amygdaloid-hippocampal complex, and cerebellum, as well as the asymmetry of the lateral ventricles. Increased volume of the lenticular nuclei and greater ventricular asymmetry (the left ventricle being larger) were found in familial cases compared with sporadic cases and normal control subjects. It is possible that increased lenticular nuclei volume and greater lateral ventricular asymmetry reflect the role of genetic factors in schizophrenia.

[Positive and negative symptoms in schizophrenia: a current overview]

The purpose of this article is to summarize the results of studies examining the validity of the positive and negative sub-types of schizophrenia as proposed by Crow. The authors summarized Crow's model's predictions in the form of 12 research questions and examined whether its predictions were confirmed. The following predictions are generally confirmed by the data collected: (i) it is possible to measure negative symptoms with accuracy; (ii) the negative symptoms predict a deterioration; (iii) the negative symptoms are generally correlated with overall cognitive deficits; (iv) each dimension appears to have distinct neurobiological substrata. However, several elements of the Crow model are not supported by the data collected. Among the necessary modifications, the most important are as follows: (i) it appears more productive to conceive of the negative symptoms as distinct dimensions, rather than distinct diseases; (ii) at least three dimensions exist for describing the symptoms of schizophrenia; (iii) the negative symptoms are not necessarily intrinsic to the schizophrenic process, and they may be due to other causes; (iv) the negative symptoms are not necessarily irreversible, and can be improved under ataractics; (v) the positive symptoms, in particular those relating to disorganization, can also be correlated with cognitive deficits.