Season of birth and obstetrical complications in schizophrenics

Obstetric complications in patients with schizophrenia and their unaffected siblings

Objective

We sought to explore whether obstetric complications (OCs) are more likely to occur in the presence of familial/genetic susceptibility for schizophrenia or whether they themselves represent an independent environmental risk factor for schizophrenia.

Methods

The presence of OCs was assessed through maternal interview on 216 subjects, comprising 36 patients with schizophrenia from multiply affected families, 38 of their unaffected siblings, 31 schizophrenic patients with no family history of psychosis, 51 of their unaffected siblings and 60 normal comparison subjects. We examined the familiality of OCs and whether OCs were commoner in the patient and sibling groups than in the control group.

Results

OCs tended to cluster within families, especially in multiply affected families. Patients with schizophrenia, especially those from multiply affected families, had a significantly higher rate of OCs compared to normal comparison subjects, but there was no evidence for an elevated rate of OCs in unaffected siblings.

Conclusion

Our data provides little evidence for a link between OCs and genetic susceptibility to schizophrenia. If high rates of OCs are related to schizophrenia genes, this relationship is weak and will only be detected by very large sample sizes.

The impact of pre- and perinatal factors on psychopathology in adulthood

BACKGROUND

There is considerable evidence that pre- and post-natal factors are associated with a wide range of psychopathology in offspring during childhood and adolescence.

OBJECTIVE

The main aims of the present study were to examine the associations between pre- and perinatal factors and psychopathology in offspring during adulthood, and to explore whether family factors (i.e., family cohesion, mother's social support, and father's social support) mediate these relationships.

METHOD

Information on pre- and perinatal events was collected from biological mothers of the participants (N = 315) when they were between 14 and 18 years who were then followed up until they reached age 30.

RESULTS

Maternal obstetric history and illness during first year were significant predictors of offspring anxiety disorder. Maternal emotional health predicted offspring affective disorder. Difficult delivery and breast feeding predicted disruptive disorder. The relationship between maternal obstetric history/emotional health and anxiety/affective disorder was no longer significant after controlling for family cohesion.

LIMITATIONS

The information was based on maternal recall when their offspring were between 14 and 18 years which may be subjected to recall bias.

CONCLUSION

The association between pre- and postnatal factors and psychopathology of offspring during adulthood is mediated by familial factors.

The Integration of the Glutamatergic and the White Matter Hypotheses of Schizophrenia's Etiology

BACKGROUND

schizophrenia's endophenotipic profile is not only generally complex, but often varies from case to case. The perspective of trying to define specific anatomic correlates of the syndrome has led to disappointing results. In that context, neurophysiologic hypotheses (e.g. glutamatergic hypothesis) and connectivity hypotheses became prominent. Nevertheless, despite their commitment to the principle of denying 'localist' views and approaching the syndrome's endophenotype from a whole brain perspective, efforts to integrate both have not flourished at this moment in time.

OBJECTIVES

This paper aims to introduce a new etiological model that integrates the glutamatergic and the WM (WM) hypotheses of schizophrenia's etiology. This model proposes to serve as a framework in order to relate to patterns of brain abnormalities from the onset of the syndrome to stages of advanced chronification.

HIGHLIGHTS

Neurotransmitter abnormalities forego noticeable WM abnormalities. The former, chiefly represented by NMDAR hypo-function and associated molecular cascades, is related to the first signs of cell loss. This process is both directly and indirectly integrated to the underpinning of WM structural abnormalities; not only is the excess of glutamate toxic to the WM, but its disruption is associated to the expression of known genetic risk factors (e.g., NRG-1). A second level of the model develops the idea that abnormal neurotransmission within specific neural populations ('motifs') impair particular cognitive abilities, while subsequent WM structural abnormalities impair the integration of brain functions and multimodality. As a result of this two-stage dynamic, the affected individual progresses from experiencing specific cognitive and psychological deficits, to a condition of cognitive and existential fragmentation, linked to hardly reversible decreases in psychosocial functioning.

Epigenetic mechanisms in schizophrenia

Epidemiological research suggests that both an individual's genes and the environment underlie the pathophysiology of schizophrenia. Molecular mechanisms mediating the interplay between genes and the environment are likely to have a significant role in the onset of the disorder. Recent work indicates that epigenetic mechanisms, or the chemical markings of the DNA and the surrounding histone proteins, remain labile through the lifespan and can be altered by environmental factors. Thus, epigenetic mechanisms are an attractive molecular hypothesis for environmental contributions to schizophrenia. In this review, we first present an overview of schizophrenia and discuss the role of nature versus nurture in its pathology, where 'nature' is considered to be inherited or genetic vulnerability to schizophrenia, and 'nurture' is proposed to exert its effects through epigenetic mechanisms. Second, we define DNA methylation and discuss the evidence for its role in schizophrenia. Third, we define posttranslational histone modifications and discuss their place in schizophrenia. This research is likely to lead to the development of epigenetic therapy, which holds the promise of alleviating cognitive deficits associated with schizophrenia.

Gene-environment interaction and covariation in schizophrenia: the role of obstetric complications

While genetic factors account for a significant proportion of liability to schizophrenia, a body of evidence attests to a significant environmental contribution. Understanding the mechanisms through which genetic and environmental factors coalesce in influencing schizophrenia is critical for elucidating the pathways underlying psychotic illness and for developing primary prevention strategies. Although obstetric complications (OCs) remain among the most well-documented environmental indicators of risk for schizophrenia, the pathogenic role they play in the etiology of schizophrenia continues to remain poorly understood. A question of major importance is do these factors result from a genetic diathesis to schizophrenia (as in gene-environment covariation), act additively or interactively with predisposing genes for the disorder in influencing disease risk, or independently cause disease onset? In this review, we evaluate 3 classes of OCs commonly related to schizophrenia including hypoxia-associated OCs, maternal infection during pregnancy, and maternal stress during pregnancy. In addition, we discuss several mechanisms by which OCs impact on genetically susceptible brain regions, increasing constitutional vulnerability to neuromaturational events and stressors later in life (ie, adolescence), which may in turn contribute to triggering psychosis.

Drug development for CNS disorders: strategies for balancing risk and reducing attrition

Disorders of the central nervous system (CNS) are some of the most prevalent, devastating and yet poorly treated illnesses. The development of new therapies for CNS disorders such as Alzheimer's disease has the potential to provide patients with significant improvements in quality of life, as well as reduce the future economic burden on health-care systems. However, few truly innovative CNS drugs have been approved in recent years, suggesting that there is a considerable need for strategies to enhance the productivity of research and development in this field. In this article, using illustrative examples from neurological and psychiatric disorders, we describe various approaches that are being taken to discover CNS drugs, discuss their relative merits and consider how risk can be balanced and attrition reduced.

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.

Neurologic signs of cerebellar and cortical sensory dysfunction in schizophrenics and their relatives

Previous research has found that both schizophrenics and their relatives have significantly elevated rates of clinical neurologic signs--including 'hard' signs screened to exclude artifacts. The present study examined whether hard signs that indicate relatively localized dysfunction in particular brain regions significantly distinguish schizophrenics and/or their non-schizophrenic relatives from psychiatrically normal controls and patients with other disorders. All patients were diagnosed with DSM-III or DSM-IIIR criteria, using information from structured interviews, supplemented by chart review and family informants. Subjects were administered clinical neurologic examinations by a neurologist blind to diagnosis. The proband sample, composed of 54 schizophrenic or schizoaffective subjects, had a significantly greater proportion of subjects with signs of cerebellar dysfunction than any of the comparison samples, which included: 44 control subjects, 24 patients with substance abuse, 37 patients with bipolar disorder, and 73 of the probands' non-schizophrenic parents and adult siblings. Proportions of both probands and their relatives with signs of dysfunction of sensory cortex were significantly higher than for other groups. Cerebellar and sensory cortical dysfunctions may distinguish different subgroups of schizophrenics and may tend to reflect, respectively, non-familial and familial neuropathological factors.

Pre- and perinatal complications and risk for bipolar disorder: a retrospective study

BACKGROUND

Many studies have reported that obstetric complications are risk factors for schizophrenia, but few studies have examined whether complications increase risk for bipolar disorder.

METHODS

Bipolar-disorder probands and their adult siblings were diagnosed using DSM-III-R criteria. Obstetrical data from maternal reports were scored, blind to diagnosis, applying published scales that take into account number and severity of complications.

RESULTS

Obstetric complication scores were significantly worse in probands than siblings without mood disorders.

LIMITATIONS

Probands had relatively severe symptoms; research using more heterogeneous samples is needed.

CONCLUSION

Results suggest obstetric complications are etiologically significant in bipolar disorder.

Perinatal characteristics and schizophrenia: electrodermal activity as a mediating link in a vulnerability-stress perspective

Vulnerability-stress models of schizophrenia assert that the disorder results from an interaction between genetic or biologically acquired vulnerability and unfavourable environmental conditions. As our knowledge of early environmental factors for schizophrenia evolves, the question of links between early factors and a development of schizophrenia becomes more important. In this article, we analyse the relationship between obstetrical complications (OCs) and adult schizophrenia and methodological concerns in the search for pre- and perinatal risk factors. We review findings of aberrant electrodermal activity in schizophrenic patients and suggest that OCs may induce insults to cerebral structures that are critically involved in the control of orienting and of autonomic responses.

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.

Does choice of scale for scoring obstetric complications influence their relationship to other etiological risk factors in schizophrenia?

The relationships between obstetric complications (OCs) and both family history of psychosis and season of birth were investigated among 70 demographically matched pairs of schizophrenic patients and control cases by using OC scores produced by three different OC scales. OCs were studied through blindly assessed hospital records. The particular OC scale had a great influence on the nature of the relationships observed between OCs and both family history and season of birth. Across the three scales, the findings varied from no relationship at all to completely opposite relationships between OCs and both of the other variables. More attention needs to be paid to OC methodological differences as a source of variation in study outcome, and attempts should be made to standardize methods for OC assessment across studies.

Relationship of birth season to clinical features, family history, and obstetric complication in schizophrenia

Birth in late winter and spring has been consistently shown to be a risk factor of schizophrenia. The relationship of late winter/spring birth to clinical characteristics and other putative risk factors, such as family history and obstetric complications, may provide clues to etiology. Data relating to season of birth, clinical features, family history, and obstetric complications were analyzed for 192 patients with schizophrenia as defined by Research Diagnostic Criteria (including schizoaffective disorder). There was no significant association of season of birth with any of the psychopathological dimensions nor was there a significant association with obstetric variables or family history. However, winter-born schizophrenic patients who had a negative family history were more likely to have a history of obstetric complications. These findings suggest that obstetric complications associated with schizophrenia are perhaps the result of some seasonal risk factors important in those without a family history of the disorder.