The clinical stigmata of aberrant neurodevelopment in schizophrenia

Machine learning for prediction of schizophrenia based on identifying the primary and interaction effects of minor physical anomalies

In the neurodevelopmental model of schizophrenia, minor physical anomalies (MPAs) are considered neurodevelopmental markers of schizophrenia. To date, there has been no research to evaluate the interaction between MPAs. Our study built and used a machine learning model to predict the risk of schizophrenia based on measurements of MPA items and to investigate the potential primary and interaction effects of MPAs. The study included 470 patients with schizophrenia and 354 healthy controls. The models used are classical statistical model, Logistic Regression (LR), and machine leaning models, Decision Tree (DT) and Random Forest (RF). We also plotted two-dimensional scatter diagrams and three-dimensional linear/quadratic discriminant analysis (LDA/QDA) graphs for comparison with the DT dendritic structure. We found that RF had the highest predictive power for schizophrenia (Full-training AUC = 0.97 and 5-fold cross-validation AUC = 0.75). We identified several primary MPAs, such as the mouth region, high palate, furrowed tongue, skull height and mouth width. Quantitative MPA analysis indicated that the higher skull height and the narrower mouth width, the higher the risk of schizophrenia. In the interaction, we further identified that skull height and mouth width, furrowed tongue and skull height, high palate and skull height, and high palate and furrowed tongue, showed significant two-item interactions with schizophrenia. A weak three-item interaction was found between high palate, skull height, and mouth width. In conclusion, we found that the two machine learning methods showed good predictive ability in assessing the risk of schizophrenia using the primary and interaction effects of MPAs.

Development and validation of a web-based prediction tool on minor physical anomalies for schizophrenia

In support of the neurodevelopmental model of schizophrenia, minor physical anomalies (MPAs) have been suggested as biomarkers and potential pathophysiological significance for schizophrenia. However, an integrated, clinically useful tool that used qualitative and quantitative MPAs to visualize and predict schizophrenia risk while characterizing the degree of importance of MPA items was lacking. We recruited a training set and a validation set, including 463 schizophrenia patients and 281 healthy controls to conduct logistic regression and the least absolute shrinkage and selection operator (Lasso) regression to select the best parameters of MPAs and constructed nomograms. Two nomograms were built to show the weights of these predictors. In the logistic regression model, 11 out of a total of 68 parameters were identified as the best MPA items for distinguishing between patients with schizophrenia and controls, including hair whorls, epicanthus, adherent ear lobes, high palate, furrowed tongue, hyperconvex fingernails, a large gap between first and second toes, skull height, nasal width, mouth width, and palate width. The Lasso regression model included the same variables of the logistic regression model, except for nasal width, and further included two items (interpupillary distance and soft ears) to assess the risk of schizophrenia. The results of the validation dataset verified the efficacy of the nomograms with the area under the curve 0.84 and 0.85 in the logistic regression model and lasso regression model, respectively. This study provides an easy-to-use tool based on validated risk models of schizophrenia and reflects a divergence in development between schizophrenia patients and healthy controls (https://www.szprediction.net/).

Neurodevelopment and inflammatory patterns in schizophrenia in relation to pathophysiology

As for other major psychoses, the etiology of schizophrenia still remains poorly understood, involving genetic and epigenetic mechanisms, as well as environmental contributions. In addition, immune alterations have been widely reported in schizophrenic patients, involving both the unspecific and specific pathways of the immune system, and suggesting that infectious/autoimmune processes play an important role in the etiopathogenesis of the disorder. Cytokines, in particular, are supposed to play a critical role in infectious and inflammatory processes, mediating the cross-talk between the brain and the immune system. In this perspective, even though mixed results have been reported, it seems that schizophrenia is associated with an imbalance in inflammatory cytokines. Alterations in the inflammatory and immune systems, moreover, seem to be already present in the early stages of schizophrenia and connected to the neurodevelopmental hypothesis of the disorder, identifying its roots in brain development abnormalities that do not manifest themselves until adolescence or early adulthood. At the same time, neuropathological and longitudinal studies in schizophrenia also support a neurodegenerative hypothesis and, more recently, a novel mixed hypothesis, integrating neurodevelopmental and neurodegenerative models, has been put forward. The present review aims to provide an updated overview of the connections between the immune and inflammatory alterations and the aforementioned hypotheses in schizophrenia.

Minor physical anomalies in patients with schizophrenia in a Chinese population

Studies have shown that minor physical anomalies (MPAs) may be associated with schizophrenia. However, it remains unclear whether any items of MPAs are more associated with schizophrenia than the others. We aimed to examine which specific MPAs are more associated with schizophrenia than others. A total of 154 patients with schizophrenia and 152 healthy controls were assessed using candidate MPAs items along with items from the Waldrop scale. Significant differences were found between the patients and controls in inner canthal distance, epicanthus, adherent ear lobe, cuspidal ear and length difference from section index to ring finger (2D:4D length difference) as well as gap between the first and the second toes. These six items were selected by the logistic regression model, which correctly classified 89.0% of patients with schizophrenia (sensitivity) and 96.7% of healthy controls (specificity). The overall classification success rate was 92.8%. MPAs are associated with neurodevelopment, especially 2D:4D associated with cerebral lateralisation. Hence, our present findings support that it is necessary to evaluate MPAs beyond the Waldrop scale, as some item, such as 2D:4D length difference may reflect the more detailed aberrant neurodevelopment of schizophrenia.

White matter neuron alterations in schizophrenia and related disorders

Increased density and altered spatial distribution of subcortical white matter neurons (WMNs) represents one of the more well replicated cellular alterations found in schizophrenia and related disease. In many of the affected cases, the underlying genetic risk architecture for these WMN abnormalities remains unknown. Increased density of neurons immunoreactive for Microtubule-Associated Protein 2 (MAP2) and Neuronal Nuclear Antigen (NeuN) have been reported by independent studies, though there are negative reports as well; additionally, group differences in some of the studies appear to be driven by a small subset of cases. Alterations in markers for inhibitory (GABAergic) neurons have also been described. For example, downregulation of neuropeptide Y (NPY) and nitric oxide synthase (NOS1) in inhibitory WMN positioned at the gray/white matter border, as well as altered spatial distribution, have been reported. While increased density of WMN has been suggested to reflect disturbance of neurodevelopmental processes, including neuronal migration, neurogenesis, and cell death, alternative hypotheses--such as an adaptive response to microglial activation in mature CNS, as has been described in multiple sclerosis--should also be considered. We argue that larger scale studies involving hundreds of postmortem specimens will be necessary in order to clearly establish the subset of subjects affected. Additionally, these larger cohorts could make it feasible to connect the cellular pathology to environmental and genetic factors implicated in schizophrenia, bipolar disorder, and autism. These could include the 22q11 deletion (Velocardiofacial/DiGeorge) syndrome, which in some cases is associated with neuronal ectopias in white matter.

Dermatoglyphic indices and minor physical anomalies in patients with schizophrenia and related disorders, their first-degree biological relatives, and non psychiatric controls

Abnormalities in dermatoglyphic indices and minor physical anomalies (MPAs) are two permanent markers of fetal development that have been studied in schizophrenia. This study sought to: (1) compare select dermatoglyphic indices across patients, first-degree relatives, and non psychiatric controls; (2) assess for associations between dermatoglyphic indices and symptoms in patients and schizotypal features in relatives and controls; and (3) examine correlations between dermatoglyphics and MPAs. The two types of markers were assessed in 62 patients with schizophrenia and related disorders, 36 of their unaffected first-degree relatives, and 47 non psychiatric controls. Symptoms were measured in patients and schizotypy was assessed in relatives and controls. Analyses took into account potential demographic confounders and non independence between patients and relatives. No significant differences in dermatoglyphic indices (total finger ridge count; ridge count asymmetry; numbers of arches, loops, and whorls) were found across the three groups. Patients' and their own relatives' dermatoglyphic indices were moderately to strongly correlated (rho=0.33-0.66). Dermatoglyphic indices were unrelated to patients' cross-sectional symptom severity and were generally unrelated to relatives' and controls' levels of schizotypy. Several correlations among dermatoglyphic indices and MPAs were found in this exploratory analysis, particularly among relatives and controls. Implications for future research are discussed.

Physical manifestations of neurodevelopmental disruption: are minor physical anomalies part of the syndrome of schizophrenia?

The well-documented excess of minor physical anomalies (MPAs) among individuals with schizophrenia generally supports the neurodevelopmental model, which posits that both genetic and environmental factors contribute to structural and functional brain changes in the intrauterine and perinatal periods that predispose one to developing schizophrenia. This review synthesizes select areas of research findings on MPAs to address the question, Are MPAs part of the syndrome of schizophrenia? Although MPAs are not specific to schizophrenia, their presence in some patients indicates that aberrations in the development of the nervous system contribute to risk for the disorder. The broadly defined, heterogeneous MPA construct may be of limited value in further elucidating the specific pathophysiology of schizophrenia, though particular anomalies, such as those pertaining to nasal volumes, palatal abnormalities, or craniofacial morphology, may be informative. Given the availability of more sophisticated microarray technologies, and in light of recent findings on spontaneous mutations in patients with schizophrenia, it is possible that MPAs will prove to be useful in identifying etiologic subtypes and/or the loci of genetic risk factors. It remains to be determined whether MPAs-which, of course, are fixed markers present throughout childhood and adolescence well before the onset of the prodrome and psychosis-may have utility in terms of risk stratification for future preventive efforts. Taken together, research findings on MPAs indicate that these minor anomalies are indeed part of some schizophrenia syndromes, representing a stable systemic or physical set of manifestations of the underlying neurodevelopmental processes that lead to the illness.

Minor physical anomalies in affective disorders. A review of the literature

BACKGROUND

The increased frequency of MPAs may be external markers of abnormal brain development in affective disorders.

METHODS

A MEDLINE, psychInfo and Web of Science search was evaluated to collect all publications on the prevalence of minor physical anomalies in bipolar affective disorder and unipolar major depression.

AIMS

As reports on the prevalence of MPAs in affective disorders were controversial, were based on highly different number of patients and were evaluated by the use of scales with different sensitivities, we considered as important to review the current state of knowledge and to recommend directions to further research.

RESULTS

14 publications on 12 studies were found after a careful literature search. 5 studies have dealt with the prevalence of MPAs in bipolar affective disorder, 3 have reported on examinations among patients with unipolar major depression, while 5 publications on 3 studies combined patients with bipolar affective disorder, schizoaffective disorder and unipolar major depression. 1 study was published on the prevalence of MPAs among mood disorders, without the differentiation of the data of patients with bipolar affective disorder and unipolar major depression.

LIMITATIONS

Few studies with relatively small size were published, there is no data on the distinction between bipolar I and bipolar II disorders.

CONCLUSION

The reviewed data suggest a higher probability of the role of an aberrant neurodevelopment in bipolar affective disorder and a smaller in unipolar major depression.

Is schizophrenia a syndrome of accelerated aging?

Schizophrenia is associated with a number of anatomical and physiological abnormalities outside of the brain, as well as with a decrease in average life span estimated at 20% in the United States. Some studies suggest that this increased mortality is not entirely due to associated causes such as suicide and the use of psychotropic medications. In this article, in order to focus greater attention on the increased mortality associated with schizophrenia, we present a special case of the hypothesis that physiological abnormalities associated with schizophrenia make a contribution to the increased mortality of schizophrenia: specifically, the hypothesis that schizophrenia is a syndrome of accelerated aging. Evidence consistent with this hypothesis comes from several areas. The biological plausibility of the hypothesis is supported by the existence of established syndromes of accelerated aging and by the sharing of risk factors between schizophrenia and other age-related conditions. We propose methods for testing the hypothesis.

Recruitment of PCM1 to the centrosome by the cooperative action of DISC1 and BBS4: a candidate for psychiatric illnesses

CONTEXT

A role for the centrosome has been suggested in the pathology of major mental illnesses, especially schizophrenia (SZ).

OBJECTIVES

To show that pericentriolar material 1 protein (PCM1) forms a complex at the centrosome with disrupted-in-schizophrenia 1 (DISC1) and Bardet-Biedl syndrome 4 protein (BBS4), which provides a crucial pathway for cortical development associated with the pathology of SZ. To identify mutations in the PCM1 gene in an SZ population.

DESIGN

Interaction of DISC1, PCM1, and BBS proteins was assessed by immunofluorescent staining and coimmunoprecipitation. Effects of PCM1, DISC1, and BBS on centrosomal functions and corticogenesis in vivo were tested by RNA interference. The PCM1 gene was examined by sequencing 39 exons and flanking splice sites.

SETTING

Probands and controls were from the collection of one of us (A.E.P.).

PATIENTS

Thirty-two probands with SZ from families that had excess allele sharing among affected individuals at 8p22 and 219 white controls.

MAIN OUTCOME MEASURES

Protein interaction and recruitment at the centrosome in cells; neuronal migration in the cerebral cortex; and variant discovery in PCM1 in patients with SZ.

RESULTS

PCM1 forms a complex with DISC1 and BBS4 through discrete binding domains in each protein. DISC1 and BBS4 are required for targeting PCM1 and other cargo proteins, such as ninein, to the centrosome in a synergistic manner. In the developing cerebral cortex, suppression of PCM1 leads to neuronal migration defects, which are phenocopied by the suppression of either DISC1 or BBS4 and are exacerbated by the concomitant suppression of both. Furthermore, a nonsense mutation that segregates with SZ spectrum psychosis was found in 1 family.

CONCLUSIONS

Our data further support for the role of centrosomal proteins in cortical development and suggest that perturbation of centrosomal function contributes to the development of mental diseases, including SZ.

The prevention of schizophrenia

Preventive strategies can be divided into universal, selective and indicated prevention and early intervention. Universal interventions are directed to the general population. Selective approaches are targeted at people who have risk factors for an illness, but who do not show any current signs. Indicated approaches target high risk individuals with minimal signs or symptoms foreshadowing mental disorder, but who do not meet diagnostic levels at the current time. Early intervention involves treating those with already diagnosable disorder in a timely and optimal manner aiming to decrease the severity of the illness, and reduce secondary morbidity. Although universal and selective interventions are not yet viable strategies, indicated prevention and early intervention are now realistic possibilities in schizophrenia. Development of methods to identify those at risk of psychosis continues to evolve. Promising results in the prevention and delay of transition to psychotic disorder from high risk state have been found. Early intervention in schizophrenia, including promotion of early help-seeking, has been shown to reduce the duration of untreated psychosis, which is known to be associated with poor outcome in schizophrenia. Early intervention programmes which optimise the care of the first episode have been shown to produce better outcomes than routine management.

Neurological soft signs and minor physical anomalies in patients with schizophrenia and related disorders, their first-degree biological relatives, and non-psychiatric controls

BACKGROUND

Subtle neurological impairments and inconsequential minor anomalies of the face and limbs are manifestations of neurodevelopmental and ontogenic abnormalities that are consistently found at higher rates in individuals with schizophrenia compared to healthy controls. Limited research has been conducted on these traits among biological relatives of patients with schizophrenia. This study hypothesized that the mean NSS score and the mean MPA score would be greater in patients than controls and that first-degree relatives would have intermediate scores. Furthermore, it was hypothesized that NSS scores and MPA scores would not be correlated. This study also explored correlations between patients' NSS and MPA scores and their relatives' respective scores and sought to replicate the finding that NSS are associated with negative and disorganized symptoms of schizophrenia, whereas MPAs are not.

METHODS

Patients with schizophrenia and related psychotic disorders (n=73), first-degree relatives (n=44), and non-psychiatric controls (n=54) were assessed. Measures included the Neurological Evaluation Scale, a structured examination for MPAs, and the Positive and Negative Syndrome Scale in patients. Analyses accounted for clustering within families.

RESULTS

Both NSS and MPAs were greater in patients than controls, and first-degree relatives had intermediate scores. Furthermore, NSS and MPA scores were independent in all three groups. Correlations were found between patients' and their relatives' scores on one NES subscale (sensory integration) and total MPA score and several MPA regions (eyes, ears, and hands). This study replicated previous findings that in patients with schizophrenia, NSS are associated with negative, disorganized, and other domains of symptoms. Associations between MPAs and symptoms were sparse and inconsistent.

CONCLUSION

These findings suggest that NSS and MPAs represent two quite distinct markers of risk for schizophrenia that may stem from genetic factors, as well as from environmental/developmental influences. Future research on multivariable risk prediction models may benefit from the use of somewhat independent risk markers or endophenotypes.

Facial measurement differences between patients with schizophrenia and non-psychiatric controls

OBJECTIVE

Several previous reports suggest that facial measurements in patients with schizophrenia differ from those of non-psychiatric controls. Because the face and brain develop in concert from the same ectodermal tissue, the study of quantitative craniofacial abnormalities may give clues to genetic and/or environmental factors predisposing to schizophrenia. Using a predominantly African American sample, the present research question was two-fold: (1) Do patients differ from controls in terms of a number of specific facial measurements?, and (2) Does cluster analysis based on these facial measurements reveal distinct facial morphologies that significantly discriminate patients from controls?

METHOD

Facial dimensions were measured in 73 patients with schizophrenia and related psychotic disorders (42 males and 31 females) and 69 non-psychiatric controls (35 males and 34 females) using a 25-cm head and neck caliper. Due to differences in facial dimensions by gender, separate independent samples Student's t-tests and logistic regression analyses were employed to discern differences in facial measures between the patient and control groups in women and men. Findings were further explored using cluster analysis. Given an association between age and some facial dimensions, the effect of age was controlled.

RESULTS

In unadjusted bivariate tests, female patients differed from female controls on several facial dimensions, though male patients did not differ significantly from male controls for any facial measure. Controlling for age using logistic regression, female patients had a greater mid-facial depth (tragus-subnasale) compared to female controls; male patients had lesser upper facial (trichion-glabella) and lower facial (subnasale-gnathion) heights compared to male controls. Among females, cluster analysis revealed two facial morphologies that significantly discriminated patients from controls, though this finding was not evident when employing further cluster analyses using secondary distance measures. When the sample was restricted to African Americans, results were similar and consistent.

CONCLUSIONS

These findings indicate that, in a predominantly African American sample, some facial measurements differ between patients with schizophrenia and non-psychiatric controls, and these differences appear to be gender-specific. Further research on gender-specific quantitative craniofacial measurement differences between cases and controls could suggest gender-specific differences in embryologic/fetal neurodevelopmental processes underpinning schizophrenia.

Associations between schizotypal features and indicators of neurological and morphological abnormalities

OBJECTIVE

Limited research suggests that subtle neurological and morphological abnormalities that have been documented in patients with schizophrenia also may be associated with schizotypal traits in non-psychiatric samples. Based on the notion that neurological soft signs (NSS) may mark a genetic diathesis, this study hypothesized that NSS scores would be related to the level of schizotypy in relatives of schizophrenia patients and in controls. Additionally, associations between MPA scores and schizotypy were explored in these two groups.

METHOD

Twenty-six first-degree relatives of schizophrenia patients and 38 controls with no personal or family history of psychosis were assessed for schizotypy using the Structured Clinical Interview for DSM-IV Axis II Disorders schizotypal personality disorder module, as well as the self-administered Schizotypal Personality Questionnaire. The Neurological Evaluation Scale and a structured examination for MPAs also were administered.

RESULTS

Mean schizotypy scores did not differ between relatives and controls. Both NSS and MPAs were associated with the level of interviewer-assessed schizotypal features in controls but not in relatives of patients with schizophrenia. NSS and MPAs were not associated with self-reported schizotypy in either group.

CONCLUSIONS

These findings demonstrate that both NSS and MPAs are associated with interview-based schizotypal traits, at least in non-psychiatric participants. Future research should seek to replicate these results in other samples of relatives and controls.

Minor physical anomalies in schizophrenia: a meta-analysis

Numerous studies report an increased frequency of minor physical anomalies (MPAs) in schizophrenic individuals compared with controls. However, these studies vary considerably regarding the magnitude of the case-control disparity and the topographical distribution of the anomalies. A meta-analysis was carried out on the existing MPA literature in an effort to better understand the relationship between MPAs and schizophrenia. Following a literature search, 13 studies were identified that met our inclusion criteria. Mean total MPA scores were available for 11 of these studies, whereas only seven studies provided regional MPA scores. For both the total MPA and regional MPA analyses, pooled effect sizes (Hedges' g and pooled odds ratios, respectively) were calculated along with tests of heterogeneity. For the total MPA analyses, a meta-regression approach was used to explore the relationship between possible moderator variables (e.g., number of MPA scale items) and effect size heterogeneity. The magnitude of the pooled effect size for the total MPA scores was high (1.131; p<0.001), indicating significantly more overall MPAs in schizophrenic individuals. Significant effect size heterogeneity was present (p<0.001); however, this heterogeneity could not be explained by any of the included moderator variables. The regional MPA analysis revealed significantly increased MPAs in all six anatomical regions (p<0.05), although the pooled odds ratios for these regions did not differ significantly from one another. These results suggest a lack of regional specificity for MPAs in schizophrenia.

Theories of schizophrenia: a genetic-inflammatory-vascular synthesis

BACKGROUND

Schizophrenia, a relatively common psychiatric syndrome, affects virtually all brain functions yet has eluded explanation for more than 100 years. Whether by developmental and/or degenerative processes, abnormalities of neurons and their synaptic connections have been the recent focus of attention. However, our inability to fathom the pathophysiology of schizophrenia forces us to challenge our theoretical models and beliefs. A search for a more satisfying model to explain aspects of schizophrenia uncovers clues pointing to genetically mediated CNS microvascular inflammatory disease.

DISCUSSION

A vascular component to a theory of schizophrenia posits that the physiologic abnormalities leading to illness involve disruption of the exquisitely precise regulation of the delivery of energy and oxygen required for normal brain function. The theory further proposes that abnormalities of CNS metabolism arise because genetically modulated inflammatory reactions damage the microvascular system of the brain in reaction to environmental agents, including infections, hypoxia, and physical trauma. Damage may accumulate with repeated exposure to triggering agents resulting in exacerbation and deterioration, or healing with their removal. There are clear examples of genetic polymorphisms in inflammatory regulators leading to exaggerated inflammatory responses. There is also ample evidence that inflammatory vascular disease of the brain can lead to psychosis, often waxing and waning, and exhibiting a fluctuating course, as seen in schizophrenia. Disturbances of CNS blood flow have repeatedly been observed in people with schizophrenia using old and new technologies. To account for the myriad of behavioral and other curious findings in schizophrenia such as minor physical anomalies, or reported decreased rates of rheumatoid arthritis and highly visible nail fold capillaries, we would have to evoke a process that is systemic such as the vascular and immune/inflammatory systems.

SUMMARY

A vascular-inflammatory theory of schizophrenia brings together environmental and genetic factors in a way that can explain the diversity of symptoms and outcomes observed. If these ideas are confirmed, they would lead in new directions for treatments or preventions by avoiding inducers of inflammation or by way of inflammatory modulating agents, thus preventing exaggerated inflammation and consequent triggering of a psychotic episode in genetically predisposed persons.

Prediction and prevention of transition to psychosis in young people at incipient risk for schizophrenia

The treatment of psychotic disorders, particularly schizophrenia, had been viewed with pessimism until a recent shift in focus from established or chronic illness to earlier phases of illness around the onset highlighted opportunities for enhanced recovery. Associated with this change in focus of research and clinical efforts has been the recognition that the biological and social changes underpinning the development of psychotic disorders may already be active in the pre-psychotic or prodromal phase. It has therefore been suggested that efforts toward the prevention of psychotic disorders should focus on the emerging illness. This article provides a review of work that has been conducted at the PACE Clinic in Melbourne, Australia since 1994. This clinical research program was established to develop strategies for the identification of young people at high risk of developing a psychotic disorder within a short period of time- primarily by virtue of recent mental state changes. Additionally, biological and psychological processes that have been proposed to underlie the development of illness have been investigated and potential preventive interventions have been evaluated.

The PACE Clinic: identification and management of young people at "ultra" high risk of psychosis

Over the past decade, both clinical and research interest in the early stages of psychotic disorders has grown. This has been associated with research suggesting that early intervention in these disorders may limit their impact on the life of the affected individual and his or her family. It has also been recognized that the biological and psychological changes underpinning the development of psychotic disorders may already be active in the prepsychotic or prodromal phase. It has been suggested that efforts to prevent psychotic disorders should be focused on this phase of emerging illness. In this article, the authors review work conducted at the PACE Clinic in Melbourne, Australia since 1994. This clinical research program was established to develop strategies for identifying young people at high risk for developing a psychotic disorder within a short period. The program has also investigated biological and psychological processes thought to underlie the development of psychosis and evaluated potential preventive interventions.

Minor physical anomalies in schizophrenia and bipolar affective disorder

OBJECTIVE

The prevalence of minor physical anomalies (MPAs) (prenatal errors of morphogenesis) was evaluated in patients with schizophrenia and bipolar affective disorder.

METHOD

A new modification of the Waldrop-scale was used to detect the presence or absence of 57 MPAs in 30 patients with schizophrenia, 30 with bipolar disorder, and in 30 matched normal controls.

RESULTS

Patients with schizophrenia compared to normal controls had significantly higher rates of three minor malformations (furrowed tongue, flat occiput, primitive shape of ears) and those of one phenogenetic variant (wide distance between toes 1 and 2), and they also had a significantly higher rate of one minor malformation (primitive shape of ears), as compared to patients with bipolar disorder. In patients with bipolar disorder, furrowed tongue was significantly more common than in controls.

CONCLUSIONS

These results support an 'early' neuro-developmental model of schizophrenia.

Neurodevelopmental schizophrenia: obstetric complications, birth weight, premorbid social withdrawal and learning disabilities

Neurodevelopmental schizophrenia seems to be caused by impaired cerebral development and is supposed to be associated with obstetric complications (OCs), poor premorbid adjustment, schizotypal or schizoid personality traits and negative symptoms. In the present study, 36 schizophrenic and schizoaffective patients and their same-sex, healthy siblings were recruited. They were diagnosed according to DSM-III-R, using structured psychiatric interviews and a consensus of 2 psychiatrists. Information on OCs, birth weight, premorbid social and learning functioning was obtained from their mothers. The main results show significant differences in OCs, birth weight, premorbid social and learning functioning between patients and their same-sex, healthy siblings. Using multivariate analyses, both premorbid variables were again identified to discriminate well between affected and unaffected siblings. Our findings seem to confirm the concept of schizophrenia as a neurodevelopmental process.

The evolutionary genetic underpinnings of schizophrenia: the developmental instability model

The importance of genes in the etiology of schizophrenia is well known, but the manner in which the relevant genomic factors influence neural development and the nature of selection forces operating on these factors are poorly understood. In several prominent papers, Crow has provided a unique and comprehensive theory that attempts to deal with these issues. A central aspect of his theory is that a single gene leads to reduced cerebral lateralization, increased ventricular size, and risk for developing schizophrenia. He relies greatly on Annett's right shift theory of individual variation in handedness. An alternative approach, based on the construct of developmental instability, provides a different way to conceptualize genetic influences, selection forces, and atypical lateralization in schizophrenia. We suggest that the developmental instability model has stronger empirical support and is better grounded in contemporary evolutionary genetics.

The neuropathology of schizophrenia. A critical review of the data and their interpretation

Despite a hundred years' research, the neuropathology of schizophrenia remains obscure. However, neither can the null hypothesis be sustained--that it is a 'functional' psychosis, a disorder with no structural basis. A number of abnormalities have been identified and confirmed by meta-analysis, including ventricular enlargement and decreased cerebral (cortical and hippocampal) volume. These are characteristic of schizophrenia as a whole, rather than being restricted to a subtype, and are present in first-episode, unmedicated patients. There is considerable evidence for preferential involvement of the temporal lobe and moderate evidence for an alteration in normal cerebral asymmetries. There are several candidates for the histological and molecular correlates of the macroscopic features. The probable proximal explanation for decreased cortical volume is reduced neuropil and neuronal size, rather than a loss of neurons. These morphometric changes are in turn suggestive of alterations in synaptic, dendritic and axonal organization, a view supported by immunocytochemical and ultrastructural findings. Pathology in subcortical structures is not well established, apart from dorsal thalamic nuclei, which are smaller and contain fewer neurons. Other cytoarchitectural features of schizophrenia which are often discussed, notably entorhinal cortex heterotopias and hippocampal neuronal disarray, remain to be confirmed. The phenotype of the affected neuronal and synaptic populations is uncertain. A case can be made for impairment of hippocampal and corticocortical excitatory pathways, but in general the relationship between neurochemical findings (which centre upon dopamine, 5-hydroxytryptamine, glutamate and GABA systems) and the neuropathology of schizophrenia is unclear. Gliosis is not an intrinsic feature; its absence supports, but does not prove, the prevailing hypothesis that schizophrenia is a disorder of prenatal neurodevelopment. The cognitive impairment which frequently accompanies schizophrenia is not due to Alzheimer's disease or any other recognized neurodegenerative disorder. Its basis is unknown. Functional imaging data indicate that the pathophysiology of schizophrenia reflects aberrant activity in, and integration of, the components of distributed circuits involving the prefrontal cortex, hippocampus and certain subcortical structures. It is hypothesized that the neuropathological features represent the anatomical substrate of these functional abnormalities in neural connectivity. Investigation of this proposal is a goal of current neuropathological studies, which must also seek (i) to establish which of the recent histological findings are robust and cardinal, and (ii) to define the relationship of the pathological phenotype with the clinical syndrome, its neurochemistry and its pathogenesis.