Second-trimester markers of fetal size in schizophrenia: a study of monozygotic twins

Obstetric complications in distinct schizophrenic subgroups

In 55 chronic DSM III-R schizophrenics the occurrence of obstetric complications (OCs) was investigated using the familial/sporadic strategy and Leonhard's unsystematic/systematic distinction. The overall frequency and severity of OCs did not differ between patients and controls. A sub-sample of patients, whose genetic risk was supposed to be high in both classification systems (diagnosis of unsystematic and familial schizophrenia), had significantly fewer OCs than controls on the Lewis and Murray scale (P< 0.05). With reference to previous reports of increased mortality rates in the offspring of schizophrenics, high genetic risk and additional perinatal stressors may increase perinatal mortality. In contrast, patients whose genetic risk was supposed to be low in both systems (diagnosis of systematic and sporadic schizophrenia) showed a trend to an increased frequency of OCs in the Fuchs scale. In the context of the recently reported highly significantly increased rate of maternal infections during midgestation in these patients, it was supposed that perinatal complications may be of some aetiological importance in schizophrenics with low genetic risk.

Qualitative and quantitative dermatoglyphics of chronic kidney disease of unknown origin (CKDu) in Sri Lanka

BACKGROUND

Dermatoglyphics has been used widely in fields of medicine as a non-invasive diagnostic tool and an early assessment of risk for certain medical conditions. It reflects disturbances in fetal development during early prenatal weeks 14-22 when fingerprints develop. Dermatoglyphic asymmetry has been used to measure developmental instability during a specific period of human fetal development. Thus, the present study was planned to investigate whether digital and palmar dermatoglyphics of chronic kidney disease of unknown origin (CKDu) patients in Sri Lanka are different from healthy people.

METHODS

A case control study was carried out among CKDu patients (90 males, 90 females) from a CKDu endemic area and gender-matched two control groups; one group from a CKDu endemic region (90 males, 90 females) and another group from a CKDu non-endemic region (90 males, 90 females). Dermatoglyphics were obtained using photographic methods. Both qualitative and quantitative dermatoglyphic variables were defined and analyzed according to standard criteria. Both directional (DA) and fluctuating asymmetry (FA) were assessed.

RESULTS

Several qualitative dermatoglyphic variables had significant association with CKDu. The triradii a¹ variable was less evident in palms of CKDu cases in both genders when compared to both control groups. The FA of pattern discordance (right vs left hands) between CKDu cases and control group were significant in several digits. The FA of the ridge count was found significant in several digits, and also significant for A-B ridge count and total ridge count.

CONCLUSION

Based on these results, it is proposed that the mechanisms responsible for the development of CKDu might be associated with those responsible for FA observed in CKDu patients. Accordingly, a diagnostic tool based on FA could be developed for predicting risk prior to the development of CKDu.

Prenatal adverse environment is associated with epigenetic age deceleration at birth and hypomethylation at the hypoxia-responsive EP300 gene

BACKGROUND

Obstetric complications have long been retrospectively associated with a wide range of short- and long-term health consequences, including neurodevelopmental alterations such as those observed in schizophrenia and other psychiatric disorders. However, prospective studies assessing fetal well-being during pregnancy tend to focus on perinatal complications as the final outcome of interest, while there is a scarcity of postnatal follow-up studies. In this study, the cerebroplacental ratio (CPR), a hemodynamic parameter reflecting fetal adaptation to hypoxic conditions, was analyzed in a sample of monozygotic monochorionic twins (60 subjects), part of them with prenatal complications, with regard to (i) epigenetic age acceleration, and (ii) DNA methylation at genes included in the polygenic risk score (PRS) for schizophrenia, and highly expressed in placental tissue.

RESULTS

Decreased CPR measured during the third trimester was associated with epigenetic age deceleration (β = 0.21, t = 3.362, p = 0.002). Exploration of DNA methylation at placentally expressed genes of the PRS for schizophrenia revealed methylation at cg06793497 (EP300 gene) to be associated with CPR (β = 0.021, t = 4.385; p = 0.00008, FDR-adjusted p = 0.11). This association was reinforced by means of an intrapair analysis in monozygotic twins discordant for prenatal suffering (β = 0.027, t = 3.924, p = 0.001).

CONCLUSIONS

Prenatal adverse environment during the third trimester of pregnancy is associated with both (i) developmental immaturity in terms of epigenetic age, and (ii) decreased CpG-specific methylation in a gene involved in hypoxia response and schizophrenia genetic liability.

Biometric parameters of the hand as an index of schizophrenia--a preliminary study

Since abnormalities in distal upper limb development are among the minor physical anomalies associated with schizophrenia we attempted to determine whether patients with schizophrenia can be identified on the basis of specific morphologic and dermatoglyphic features of the hand. Photographs and prints of the hands of 38 patients with schizophrenia and those of 42 control subjects were evaluated and graded on 13 biometric parameters. Results were statistically evaluated. A combination of three of the parameters was found to have good predicting abilities to distinguish between schizophrenics and controls. Subjects having high values in these three parameters were found to have a higher propensity to be defined as schizophrenics. In order to define a simple rule for classifying subjects we chose a criterion of having a value of 3 (in a scale from 1 to 3) in at least one of these three discriminating variables. This rule yielded an overall accuracy of 81.2%. Among controls, 85.7% of subjects did not fulfill such criteria, while 14.3% were defined as false positives. Among schizophrenics 76.3% achieved this condition while 23.7% were false negatives. The technique's objectivity and ease of application could facilitate the diagnosis of this disease.

The presentation of dermatoglyphic abnormalities in schizophrenia: a meta-analytic review

Within a neurodevelopmental model of schizophrenia, prenatal developmental deviations are implicated as early signs of increased risk for future illness. External markers of central nervous system maldevelopment may provide information regarding the nature and timing of prenatal disruptions among individuals with schizophrenia. One such marker is dermatoglyphic abnormalities (DAs) or unusual epidermal ridge patterns. Studies targeting DAs as a potential sign of early developmental disruption have yielded mixed results with regard to the strength of the association between DAs and schizophrenia. The current study aimed to resolve these inconsistencies by conducting a meta-analysis examining the six most commonly cited dermatoglyphic features among individuals with diagnoses of schizophrenia. Twenty-two studies published between 1968 and 2012 were included. Results indicated significant but small effects for total finger ridge count and total A-B ridge count, with lower counts among individuals with schizophrenia relative to controls. Other DAs examined in the current meta-analysis did not yield significant effects. Total finger ridge count and total A-B ridge count appear to yield the most reliable dermatoglyphic differences between individuals with and without schizophrenia.

Dermatoglyphic patterns in subtypes of schizophrenia

Dermatoglyphic patterns of fingers were studied in two hundred and fifty patients of various subtypes of schizophrenia and ninety normal control subjects. The difference between the males and female dermatoglyphic patterns in the schizophrenic and controls was found to be non significant. No difference was also found between the fingerprint patterns in patients of various subtypes of schizophrenia.

Effects of neonatal MK-801 treatment on p70S6K-S6/eIF4B signal pathways and protein translation in the frontal cortex of the developing rat brain

Systemic injections of MK-801, a selective NMDAR antagonist, into neonatal rats induces long-term neurochemical and behavioural changes. It has been suggested that these changes form the neurodevelopmental basis for schizophrenia-like behaviour in rats. In this study, 7-d-old rats were treated with MK-801, and their frontal cortices were examined to investigate the effects on p70S6K-S6 signal pathway and on protein translation, which play crucial roles in the neurodevelopmental process. MK-801, in doses of 0.5 and 1.0 mg/kg, induced a decrease in phosphorylation of p70S6K and its substrates, S6 and eIF4B, in the first 8 h, and no change at 24 and 48 h. These effects were more prominent after two injections of MK-801 than one. Decreased S6 phosphorylation by MK-801 was evident in the prefrontal, cingulate, and insular cortex. In two representative upstream p70S6K-S6 pathways related to ERK1/2 and Akt, changes in ERK1/2-p90RSK phosphorylation were accompanied by changes of p70S6K-S6. Although two MK-801 injections induced a dose-dependent decrease in phosphorylation of Akt and mTOR at 4 and 8 h, a single injection did not produce a significant effect. Protein synthesis rate, measured by [3H]leucine incorporation in frontal cortical tissue, was reduced until 24 h after two MK-801 (1.0 mg/kg) injections. In summary, this study found that neonatal MK-801 treatment induced dysregulation in the p70S6K-S6/eIF4B pathway and protein translation in the frontal cortex of the developing rat brain, which may suggest an important role of protein translation machinery in the MK-801 neurodevelopmental animal model of schizophrenia.

Sex-dependent behavioral effects and morphological changes in the hippocampus after prenatal invasive interventions in rats: implications for animal models of schizophrenia

OBJECTIVES

Although schizophrenia affects both human genders, there are gender-dependent differences with respect to age of onset, clinical characteristics, course and prognosis of the disease.

METHODS

To investigate sex-dependent differences in motor coordination and activity as well as in cognitive and social behavior, we repeatedly tested female (n = 14) and male (n = 12) Fisher rats (postnatal days, PD 56-174) that had received intracerebroventricular injections of kainic acid as well as female (n = 15) and male (n = 16) control animals. The hippocampus was examined histologically.

RESULTS

Compared to male controls, in the alcove test both female controls and female animals with prenatal intervention spent less time in a dark box before entering an unknown illuminated area. Again, animals that received prenatal injection (particularly females) made more perseveration errors in the T-maze alternation task compared to controls. Female rats exhibited a higher degree of activity than males, suggesting these effects to be sex-dependent. Finally, animals that received prenatal intervention maintained longer lasting social contacts. Histological analyses showed pyramidal cells in the hippocampal area CA3 (in both hemispheres) of control animals to be longer than those found in treated animals. Sex-dependent differences were found in the left hippocampi of control animals and animals after prenatal intervention.

CONCLUSION

These results demonstrate important differences between males and females in terms of weight gain, response to fear, working memory and social behavior. We also found sex-dependent differences in the lengths of hippocampal neurons. Further studies on larger sample sets with more detailed analyses of morphological changes are required to confirm our data.

Potential microbial origins of schizophrenia and their treatments

Schizophrenia is a severe brain disease that affects approximately 1% of the world's population. Extensive study into the indication of and causes of this disease has been ongoing for decades. Historical review of research into associated abnormalities and markers common in schizophrenic patients has demonstrated a correlation with potential microbial origins in the development of the disease. While infectious etiologies could be responsible for some cases of schizophrenia, no consistent use of anti-infective agents has been developed for its prevention or treatment. Elucidation of the mechanisms for infectious roots of schizophrenia may open new avenues for effective treatment.

The neurodevelopmental hypothesis of schizophrenia, revisited

While multiple theories have been put forth regarding the origin of schizophrenia, by far the vast majority of evidence points to the neurodevelopmental model in which developmental insults as early as late first or early second trimester lead to the activation of pathologic neural circuits during adolescence or young adulthood leading to the emergence of positive or negative symptoms. In this report, we examine the evidence from brain pathology (enlargement of the cerebroventricular system, changes in gray and white matters, and abnormal laminar organization), genetics (changes in the normal expression of proteins that are involved in early migration of neurons and glia, cell proliferation, axonal outgrowth, synaptogenesis, and apoptosis), environmental factors (increased frequency of obstetric complications and increased rates of schizophrenic births due to prenatal viral or bacterial infections), and gene-environmental interactions (a disproportionate number of schizophrenia candidate genes are regulated by hypoxia, microdeletions and microduplications, the overrepresentation of pathogen-related genes among schizophrenia candidate genes) in support of the neurodevelopmental model. We relate the neurodevelopmental model to a number of findings about schizophrenia. Finally, we also examine alternate explanations of the origin of schizophrenia including the neurodegenerative model.

New evidences of gene and environment interactions affecting prenatal neurodevelopment in schizophrenia-spectrum disorders: a family dermatoglyphic study

BACKGROUND

Several studies have reported an increase of dermatoglyphic anomalies in schizophrenic patients compared to controls. However, the recognition of specific dermatoglyphic variables related to this disorder and their genetic and/or environmental component are still controversial.

METHOD

We conducted a dermatoglyphic analysis in a new sample of 617 individuals: 205 patients with schizophrenia-spectrum disorders, 224 healthy first degree relatives and 188 healthy controls. The dermatoglyphic variables studied were: the total a-b ridge count (TABRC) and its fluctuating asymmetry (FAABRC), and the presence of ridge dissociations (RD) and abnormal palmar flexion creases (APFC).

RESULTS

Patients, relatives and controls did not differ in TABRC. However, within the patients group those with a low birth weight or absence of psychiatric family history showed lower TABRC than the others. The frequency of ectodermic derivates abnormalities (RD and/or APFC) appeared to be higher in patients and relatives than in controls, while first degree relatives did not differ from patients. Males showed an increased rate of ectodermic derivates abnormalities compared to females in all groups and male patients also presented higher FAABRC than female patients.

CONCLUSIONS

Our results suggest a different relative weight of genetic and environmental factors on each dermatoglyphic variable analyzed: i) TABRC may be a sensitive marker to environmental factors in schizophrenia, ii) ectodermal derivates abnormalities appear to be influenced by genetic risk factors, which could be involved both in the disrupted development of ectodermic derivates like dermatoglyphics and central nervous system and in the vulnerability for schizophrenia.

Ridgecounter: a program for obtaining semi-automated finger ridge counts

Finger ridge count is a valuable quantitative phenotype used in a wide range of biological and anthropological research. However, the scoring of the phenotype is both labour intensive and error prone. This paper describe a freely available software program, RIDGECOUNTER, that can be used to obtain ridge counts from digitized prints (either collected using a digital fingerprint scanner or scanned from an inked print). The program yields semi-automated ridge counts and logs the location of the user-selected core and delta points to aid in the training of new researchers and ensure the repeatability of count. In a validity study of 451 prints, the semi-automated ridge counts of digital prints showed good agreement (r = 0.957) with traditional manual counts of inked-rolled prints (which were obtained 2 years apart and counted by different researchers). In a reliability study of 200 prints, semi-automated ridge counts derived from digital prints collected at two different time points also showed good agreement (r = 0.962) (the prints were obtained 2 years apart and counted by the same researcher). Although designed for use with fingerprints, the program is suitable for use with palm, foot or toe prints using user-defined landmarks.

The International Society for Developmental Psychobiology annual meeting symposium: Impact of early life experiences on brain and behavioral development

Decades of research in the area of developmental psychobiology have shown that early life experience alters behavioral and brain development, which canalizes development to suit different environments. Recent methodological advances have begun to identify the mechanisms by which early life experiences cause these diverse adult outcomes. Here we present four different research programs that demonstrate the intricacies of early environmental influences on behavioral and brain development in both pathological and normal development. First, an animal model of schizophrenia is presented that suggests prenatal immune stimulation influences the postpubertal emergence of psychosis-related behavior in mice. Second, we describe a research program on infant rats that demonstrates how early odor learning has unique characteristics due to the unique functioning of the infant limbic system. Third, we present work on the rodent Octodon degus, which shows that early paternal and/or maternal deprivation alters development of limbic system synaptic density that corresponds to heightened emotionality. Fourth, a juvenile model of stress is presented that suggests this developmental period is important in determining adulthood emotional well being. The approach of each research program is strikingly different, yet all succeed in delineating a specific aspect of early development and its effects on infant and adult outcome that expands our understanding of the developmental impact of infant experiences on emotional and limbic system development. Together, these research programs suggest that the developing organism's developmental trajectory is influenced by environmental factors beginning in the fetus and extending through adolescence, although the specific timing and nature of the environmental influence has unique impact on adult mental health.

Behavioral and hippocampal changes after prenatal invasive interventions with possible relevance to schizophrenia

In an attempt to model neurodevelopmental defects that may contribute to the outbreak of schizophrenia after adolescence, the present study examined the effects of prenatal interventions in rats, including injections of kainic acid, on motor, cognitive and social behaviour, which was assessed repeatedly between PDs 56-62 (week 8) and 168-174 (week 24), as well as on hippocampal morphology. As compared to untreated controls (n=5-9), the offspring (n=12 or 16) of treated mothers exhibited shorter latencies to leave a dark box and enter an illuminated field on weeks 12, 16 and 20, a higher number of perseverations in a T-maze alternation task on weeks 16 and 20, longer nose contacts with strange and familiar partners in a social interaction test on weeks 12 and 16 and lower weight gains over the course of testing. They also had shorter pyramidal cells in hippocampal area CA3. Thus, the prenatally treated offspring showed certain alterations in their brains and behaviour that resembled the human condition of schizophrenia (e.g., changes at cell level in the hippocampus, perseverative behaviour, lower weight gains), although others (e.g., increased social contacts) did not.

Prenatal and postnatal maternal contributions in the infection model of schizophrenia

Epidemiological studies have indicated that the risk of schizophrenia is enhanced by prenatal maternal infection with viral or bacterial pathogens. Recent experimentation in rodents has yielded additional support for a causal relationship between prenatal immune challenge and the emergence of psychosis-related abnormalities in brain and behaviour in later life. However, little is known about the putative roles of maternal postnatal factors in triggering and modulating the emergence of psychopathology following prenatal immunological stimulation. Here, we aimed to dissect the relative contributions of prenatal inflammatory events and postnatal maternal factors in precipitating juvenile and adult psychopathology in the resulting offspring with a cross-fostering design. Pregnant mice were exposed to the viral mimic, polyriboinosinic-polyribocytidilic acid (PolyI:C; at 5 mg/kg, intravenously), or vehicle treatment on gestation day 9, and offspring born to PolyI:C- and vehicle-treated dams were then simultaneously cross-fostered to surrogate rearing mothers, which had either experienced inflammatory or vehicle treatment during pregnancy. Prenatal PolyI:C administration did not affect the expression of latent inhibition (LI) at a juvenile stage of development, but led to the post-pubertal emergence of LI disruption in both aversive classical and instrumental conditioning regardless of the postnatal rearing condition. In addition, deficits in conditioning as such led to a pre- and post-pubertal loss of LI in prenatal control animals that were adopted by PolyI:C-treated surrogate mothers. Our findings thus indicate that the adoption of prenatally immune-challenged neonates by control surrogate mothers does not possess any protective effects against the subsequent emergence of psychopathology in adulthood. At the same time, however, the present study highlights for the first time that the adoption of prenatal control animals by immune-challenged rearing mothers is sufficient to precipitate learning disabilities in the juvenile and adult offspring.

Dermatoglyphics and Schizophrenia: a meta-analysis and investigation of the impact of obstetric complications upon a-b ridge count

BACKGROUND

Patients with schizophrenia show deviances in their dermatoglyphics, in particular reductions in palmar a-b ridge counts (ABRCs), which are evidence of an early developmental deviance. However, the severity or the origin of these ABRC changes has not been established.

METHOD

(i) We examined the published literature on the ABRC in patients with schizophrenia against controls with a random effects meta-analysis. (ii) We used linear regression to study the ABRC in our sample of families including 125 patients with schizophrenia, 107 of their unaffected relatives and 98 controls. (iii) The effect of obstetric complications on the patient's ABRC was examined using the Lewis Murray scale.

RESULTS

The pooled standardised effect size of ABRC differences between patients and controls obtained by our meta-analysis was 0.39 (95% CI: 0.05-0.73; p=0.03). In our sample, there were no significant differences in ABRCs between those with schizophrenia, their relatives and controls. Only those patients with obstetric complications had significantly reduced ABRC compared to controls (p=0.01).

CONCLUSIONS

We confirmed the presence of significant yet mild ABRC reductions in schizophrenia. These represent a subtle deviance from the norm and could be present in certain subsets of patients, possibly those who suffered early developmental insults.

Dermatoglyphic anomalies in psychometrically identified schizotypic young adults

Dermatoglyphic anomalies are hypothesized to indicate disruptions in the second trimester of prenatal development, a time period that appears to be critical in the etiology of schizophrenia. The present study examined the presence of dermatoglyphic anomalies in psychometrically identified schizotypic young adults (n = 51) and control participants (n = 63) selected based upon their scores on the Perceptual Aberration [J. Abnorm. Psychology 87 (1978) 399] and Magical Ideation Scales [J. Consult. Clin. Psychol. 51 (1983) 215]. It was hypothesized that schizotypic participants would exhibit higher rates of dermatoglyphic anomalies than control participants. The Perceptual Aberration-Magical Ideation group exhibited lower total and absolute finger ridge counts and less complex pattern types than control participants--findings consistent with anomalies reported in patients with schizophrenia. These findings encourage future examination of these anomalies in individuals at-risk for schizophrenia and related disorders.

Dermatoglyphic profile in 22q deletion syndrome

A genetic subtype of schizophrenia has been described in 22q11 Deletion syndrome. Previous studies have described an excess of dermatoglyphic alterations in schizophrenia, such as low a-b ridge counts (ABRCs), a high frequency of ridge dissociations, and increased dermatoglyphic fluctuating asymmetry. Little is known however, about the dermatoglyphic profile of 22qDS subjects showing psychotic symptoms and its similarity to the previously reported anomalies in schizophrenia. We studied the palmar dermatoglyphics of 22 subjects with 22qDS of predominantly Caucasian origin, 15 of whom had psychotic illness, and in 84 healthy controls of similar ethnicity. We observed higher values for total ATD angle in cases than in controls (P = 0.04). In addition, there was an excess of radial figures in the hypothenar area in cases, especially in the left hand. Interestingly, greater fluctuating asymmetry, determined by the absolute difference between right and left ABRC, was observed in 22qDS subjects compared to controls (P = 0.05). However, no differences were found for ABRCs and frequency of dissociations. Despite the small sample size, the palmprints analyzed suggest the existence of an altered dermatoglyphic profile in 22qDS, involving: (i) ATD angle amplitude, (ii) presence of radial loops in the hypothenar area, and (iii) an increment of fluctuating asymmetry. The first two features are similar to those found in other genetic syndromes associated with low IQ, while high levels of fluctuating asymmetry have often been reported in schizophrenia.

Prenatal lead exposure, delta-aminolevulinic acid, and schizophrenia

Schizophrenia is a severe mental disorder of unknown etiology. Recent reports suggest that a number of environmental factors during prenatal development may be associated with schizophrenia. We tested the hypothesis that environmental lead exposure may be associated with schizophrenia using archived serum samples from a cohort of live births enrolled between 1959 and 1966 in Oakland, California. Cases of schizophrenia spectrum disorder were identified and matched to controls. A biologic marker of lead exposure, delta-aminolevulinic acid (delta-ALA), was determined in second-trimester serum samples of 44 cases and 75 controls. delta-ALA was stratified into high and low categories, yielding 66 subjects in the high category, corresponding to a blood lead level (BPb) greater than or equal to 15 micro g/dL, and 53 in the low category, corresponding to BPb less than 15 micro g/dL. Using logistic regression, the odds ratio (OR) for schizophrenia associated with higher delta-ALA was 1.83 [95% confidence interval (CI), 0.87-3.87; p = 0.1]. Adjusting for covariates gave an OR of 2.43 (95% CI, 0.99-5.96; p = 0.051). This finding suggests that the effects of prenatal exposure to lead and/or elevated delta-ALA may extend into later life and must be further investigated as risk factors for adult psychiatric diseases.

Directional and fluctuating asymmetry in finger and a-b ridge counts in psychosis: a case-control study

BACKGROUND

Several studies have reported alterations in finger and a-b ridge counts, and their derived measures of asymmetry, in schizophrenia compared to controls. Because ridges are fully formed by the end of the second trimester, they may provide clues to disturbed early development. The aim of this study was to assess these measures in a sample of patients with psychosis and normal controls.

METHODS

Individuals with psychosis (n = 240), and normal controls (n = 228) were drawn from a catchment-area case-control study. Differences in finger and a-b ridge count and Fluctuating Asymmetry were assessed in three group comparisons (non-affective psychosis versus controls; affective psychosis versus controls; non-affective psychosis versus affective psychosis). The analyses were performed separately for males and females.

RESULTS

There were no significant group differences for finger nor a-b ridge counts. While there were no group difference for Directional Asymmetry, for Fluctuating Asymmetry measures men with non-affective psychosis had significantly higher fluctuating asymmetry of the index finger ridge count (a) when compared to controls (FA-correlation score, p = 0.02), and (b) when compared to affective psychosis (adjusted FA-difference score, p = 0.04).

CONCLUSION

Overall, measures of finger and a-b ridge counts, and their derived measures of directional and fluctuating asymmetry were not prominent features of psychosis in this sample. While directional asymmetry in cerebral morphology is reduced in schizophrenia, this is not reflected in dermatoglyphic variables.

Immunity and schizophrenia: autoimmunity, cytokines, and immune responses

As is evident from the present account, there is no single or persuasive argument that signals emanating from the immune system are directly involved in the etiology of schizophrenia. We do not even know if we are dealing with a single disorder with a single causality; almost certainly we are not. The precise etiology of schizophrenia, as with so many neurological disorders, remains obscure. However, there is abundant evidence in schizophrenia of mutual dysregulation of neuronal function and immune system activity. Although this evidence is not always consistent, a pattern emerges suggesting aspects of immune activity being involved in the pathology of neuronal development that characterizes schizophrenia. Exposure to infective agents, HLA associations, autoimmune associations, disturbances in lymphocyte populations, and cytokine imbalances with a skew toward Th2 activity are supportive of this view. That the evidence is not always consistent is a testament to the complexity and heterogeneity of the disorder, to confounding by antipsychotics that themselves are immunomodulatory, and to the multifaceted nature, with all its checks and balances, of the immune system itself.

Schizophrenia: solving the puzzle

BACKGROUND

Schizophrenia is a common mental illness with an incidence of 15 new cases per 100,000 population per year.

AIM

To review evidence for current neurodevelopmental models of the aetiology of schizophrenia.

METHODS

We performed a literature search using Medline and PsychINFO. We evaluated the relevance of each article and tracked other relevant articles through references.

RESULTS

There is considerable evidence to support neurodevelopmental models of the aetiology of schizophrenia. One or more aetiological events occur between conception and birth that disturb central nervous system (CNS) development, leading to persisting alterations in brain structure and function. These early events, acting in concert with genetic loading and later influences or insults, predispose to the development of schizophrenia in early adulthood.

CONCLUSIONS

There have been considerable advances in schizophrenia research over the past 20 years. Future study of Indices of neural development will help advance our understanding of this common, disabling mental illness.

Differentiating between low and high susceptibility to schizophrenia in twins: the significance of dermatoglyphic indices in relation to other determinants of brain development

Both the skin and the brain develop from the same ectoderm and it is thought, therefore, that dermatoglyphics are informative for early disturbances in brain development in schizophrenia. This study was aimed at investigating the differences in both digital and palmar dermatoglyphic indices between twins discordant for schizophrenia and control twins. Furthermore, the significance of dermatoglyphic indices in relation to other determinants of brain development with regard to the susceptibility to schizophrenia was investigated. Data on dermatoglyphic indices of the hand and the palm were obtained from 21 same-sex discordant and 37 same-sex control twins. For 19 discordant and 25 control twins, there was also data available on brain volumes. Non-genetic intra-uterine circumstances early in pregnancy (10-13 weeks of gestation) are associated with a susceptibility to schizophrenia, since both the twins with schizophrenia and the unaffected co-twins showed more fluctuating asymmetry of the finger ridges (P<0.01), and marginally higher absolute finger ridge counts (P=0.06) than control twin pairs. Fluctuating asymmetry of the finger ridges was as important as whole brain and left hippocampal volumes in differentiating twins with a high susceptibility to schizophrenia from those with a low susceptibility.

Dermatoglyphic fluctuating asymmetry and atypical handedness in schizophrenia

Atypical handedness and dermatoglyphic abnormalities are hypothesized to reflect a neurodevelopmental disturbance in schizophrenia. Developmental instability, indexed by dermatoglyphic fluctuating asymmetry (FA), reflects the degree to which an individual's ontogenetic program is maintained and provides a useful framework in which to consider atypical handedness in schizophrenia. Thirty patients diagnosed with schizophrenia were compared with 37 matched healthy controls on levels of dermatoglyphic FA, a demonstration task determining hand preference and a test of relative hand skill. Multivariate analyses established that patients demonstrated greater FA and more atypical hand skill compared with controls. In patients, but not in controls, there was a strong positive association between a measure of FA and a measure of atypical hand skill, suggesting that these markers of neurodevelopmental disturbance are related in schizophrenia. On a measure of hand preference, patients were more likely than controls to be classified as mixed handed than either right or left handed. Results from the present study support the conjecture of greater developmental instability in schizophrenia affecting neurodevelopmental processes, including those conferring manual dominance.

Neurodevelopmental risk factors in schizophrenia

The authors review environmental and neurodevelopmental risk factors for schizophrenic disorders, with emphasis on minor physical anomalies, particularly craniofacial anomalies and dermatoglyphic variations. The high prevalence of these anomalies among schizophrenic subjects supports the neurodevelopmental theory of the etiology of schizophrenia, since they suggest either genetically or epigenetically controlled faulty embryonic development of structures of ectodermal origin like brain and skin. This may disturb neurodevelopment that in turn may cause these subjects to be at increased risk for the development of schizophrenia and related disorders. The precise confirmation of this theory, at least in some cases, will provide further understanding of these illnesses, allowing easy and inexpensive identification of subjects at risk and providing guidelines for the development of new pharmacological interventions for early treatment and even for primary prevention of the illness.

Developmental instability and schizotypy

INTRODUCTION

It has been suggested that evidence of developmental disturbance of cognition and lateralisation in schizophrenia can be best understood from the perspective of developmental stability (DS), an indicator of the extent to which an individual develops according to a specified ontogenic programme in the presence of environmental noise. Higher levels of fluctuating asymmetry (FA; the difference between right and left side of a quantitative morphological trait such as dermatoglyphics) are thought to reflect less DS. We examined this issue for dimensions of schizotypy.

METHODS

Associations between FA, measures of laterality and cognitive function on the one hand, and negative and positive dimensions of schizotypy on the other, were examined in a sample of 260 healthy adolescents aged 11.9-15.6years. FA was measured as a-b ridge count right-left differences. Neuropsychological measures yielded a general cognitive ability score and a frontal function score. Laterality was assessed with the Annett scale.

RESULTS

Measures of psychosis proneness were normally distributed. Negative schizotypy was associated with more FA and lower general cognitive ability in a dose-response fashion. The association with FA was more apparent in boys. No associations existed with laterality or frontal function.

CONCLUSION

The negative dimension of schizotypy may be associated with early developmental instability, resembling the pattern seen in the negative symptom dimension of schizophrenia. Measures of fluctuating asymmetry may be more sensitive with regard to the schizotypy phenotype than measures of laterality.

Relevance of sequential development of dermatoglyphics to schizophrenia

Since the embryogeneses of epidermal ridges of hands and feet are reported to be identical, although those of the feet develop two or three weeks later, a tendency for symmetry or correspondence between each side finger and toe pairs could be envisaged. Any prenatal insult could disturb such developmental mechanisms, causing the lowering of either finger or toe ridge counts which might result in augmentation of differences between them. To test this hypothesis, the differences between each side thumb and big toe ridge counts of 89 schizophrenic patients and 65 control subjects were assessed. These samples were also subgrouped into those with and without identical pattern distributions on each side of their thumb and big toe pairs. Female schizophrenics who displayed identical patterns manifested significantly greater differences between their right thumb and big toe ridge counts in comparison to the control subjects (P = 0.0142). To elucidate the contributory digit for such a greater difference, the ridge counts of the right thumbs and big toes of the female patients were compared with the corresponding counts of the control subjects. The mean ridge count of the big toes was lesser in the patient group compared with that in the control subjects, a difference, however, that did not attain statistical significance.

Methylazoxymethanol acetate-induced abnormalities in the entorhinal cortex of the rat; parallels with morphological findings in schizophrenia

It has been suggested repeatedly that the non-heritable factors in the pathogenesis of schizophrenia involve abnormalities of prenatal neurodevelopment. Furthermore, post-mortem studies show neuropathology of apparently developmental origin in the entorhinal cortex and other brain regions of schizophrenic subjects. In an attempt to model a developmental defect of the entorhinal region in the rat, cerebrocortical proliferation was briefly interrupted during its earliest stages, when the entorhinal area is thought to undergo major cell division. Specifically, the experimental set-up involved the administration of methylazoxymethanol acetate (MAM) on 1 of 4 consecutive days of embryonal development, from E9 to E12. Analysis of the forebrain in adult animals shows reduction of the entorhinal cortex in rats treated on each of these days. This effect shifts from lateral to medial divisions of the entorhinal cortex with later administration of MAM, following a known developmental gradient. Morphological consequences of MAM administration appear to be largely confined to the entorhinal cortex in the groups treated on E9 to E11, although slight reductions of the frontal and occipital neocortex were also observed in these animals. MAM treatment on E12 produces relatively more widespread damage, as reflected among other in a small reduction of brain weight. The described brain abnormalities are not accompanied by obvious phenotypical changes in any, but the E12-treated group. They, moreover, involve cortical thinning, disorganised cortical layering, and abnormal temporal asymmetries. These finding bare some similarity to observations in brains of schizophrenic subjects. The possible relevance of this approach in modeling neurodevelopmental aspects of schizophrenia is discussed.

Neurodevelopmental and neuroprogressive processes in schizophrenia. Antithetical or complementary, over a lifetime trajectory of disease?

The neurodevelopmental model of schizophrenia maintains ascendancy among current etiopathologic perspectives on schizophrenia. However, inconsistencies across studies and the absence thus far of pathognomic brain changes suggest the need for complex conceptualization of neurodevelopmental arrest, including some reconciliation with the competing neurodegenerative model of schizophrenia. This article critically reviews the preponderance of evidence for each model and provides an account of how these may interact or synergize to produce the characteristic clinical expression of schizophrenia.

The new epidemiology of schizophrenia

A confluence of findings from different vantage points has led to renewed interest and direction in the epidemiology of schizophrenia. This article provides an overview of prevalence and incidence data, examining the validity of reported secular trends in the occurrence of schizophrenia. Advances in molecular genetics have uncovered new linkage on chromosomes 6, 8, and 22 and have suggested complex models, including anticipation, to explain the perpetuation of genetic transmission in the face of low fecundity. Neurotropic viruses and autoimmunity have emerged as pathoplastic mechanisms to explain recent intriguing epidemiologic associations in schizophrenia. Environmental risk factors are also important. With attention to particular risk factors (i.e., perinatal hypoxia), a preventative approach may be realistic for some forms of schizophrenia.

Cellular and molecular neuropathology of schizophrenia: new directions from developmental neurobiology

Schizophrenia is in essence a developmental disorder, but an unusual one in that the onset of symptoms is markedly delayed. Neuropathologic studies of the brain in schizophrenia have revealed subtle abnormalities that may reflect abnormal neuronal development. A more detailed examination of the cellular and molecular pathology of schizophrenia has been limited by the lack of informative markers that might allow a more complete understanding of the brain defects that characterize this disorder. Recent advances in molecular biology have made available a growing number of probes for examining the expression of specific gene products in brain tissue by using in situ hybridization and immunohistochemistry using antibodies to recombinant antigens. Several recently cloned neural genes are expressed in the forebrain regions which have been implicated in schizophrenia, and may have significant roles in brain development or function. Selected neurotransmitter receptors, neurotrophins and their receptors, and transcription factors of the POU and MADS families are promising candidates for future studies of the cellular and molecular neuropathology of schizophrenia.

Schizophrenia in people with intellectual disability: the role of pregnancy and birth complications

The literature suggests that mental illness is more common in people with intellectual disability than in the general population. Having reviewed the literature, Turner (1989) [Psychological Medicine 19, 301-14] suggested that about 3% of people with intellectual disability also have schizophrenia. As pregnancy and birth complications (PBCs) occur more commonly in people with intellectual disability than in the general population and are also implicated in the aetiology of schizophrenia, it is possible that these conditions share a common aetiology. This study reports on the occurrence of PBCs in those people with intellectual disability who develop schizophrenia. Fifty people with intellectual disability and schizophrenia were matched for age, sex, degree of intellectual disability and presence of epilepsy with a control group who did not suffer from schizophrenia or a schizophreniform psychosis. The obstetric history was obtained and events rated on a scale specifically designed for this study. This PBCs scale consists of six sub-scales covering areas of general maternal health, pregnancy, delivery, medication in labour, total medication score and neonatal score, as well as an overall total score. The study found that people with intellectual disability who develop schizophrenia have significantly higher rates of PBCs than controls. All of the sub-scales on the PBCs scale were significantly higher in people with schizophrenia, with the exception of the medication scales. Only five out of the 50 people with schizophrenia had not had a major obstetric complication, compared to 13 subjects from the control group. A number of abnormalities were specifically higher in people who later developed schizophrenia. These included: abnormally long or short labour; maternal episiotomy; maternal preeclamptic toxaemia; induction of labour; dysmaturity; maternal smoking in pregnancy; and a delay in neonatal crying. The results suggest that PBCs are important in the aetiology of schizophrenia in people with intellectual disability.

Schizophrenia: a disorder of neurodevelopment?

For the first time, there is a pathogenic hypothesis of schizophrenia based upon reasonable empirical data. The hypothesis is that schizophrenia is a disorder arising from aberrant brain development. The neurodevelopmental view of schizophrenia is supported by neuropathological, epidemiological and clinical findings. Here, the evidence in favour of the model is summarized, together with a consideration of its weaknesses.

Age-period-cohort analysis of the incidence of schizophrenia in Scotland

Studies examining a possible decline in the incidence of schizophrenia over the last two to three decades have paid little attention to the possible role of birth cohort effects. We collected data on a Scottish national sample of all schizophrenic patients, admitted for the first time between 1966 and 1990 (N = 11348; male = 6301). In an Age-Period-Cohort analysis, a full model, incorporating three factors, had a substantially better fit to the data than other models (especially, an Age-Period model), providing clear evidence of the presence of a cohort effect. After adjustment for the effects of age and period, there was a 55% reduction in the rate of schizophrenia in men and a 39% fall in the number of women over the 50-year birth period from 1923 to 1973. The marked decline in the first admission rates observed in Scotland cannot, however, be attributed entirely to this cohort effect. Rather, a greater proportion of the declining first admission rates (88%) is ascribed to the period effect (i.e. artefactual or causally related cross-sectional effects). Nevertheless, the fact that a birth-cohort effect accounts for part of the declining incidence, suggests that causal environmental factors operating early in life have been diminishing in intensity.

Dermatoglyphic a-b ridge count as a possible marker for developmental disturbance in schizophrenia: replication in two samples

The aim of this study was to conduct an epidemiological analysis of quantitative dermatoglyphic traits as a marker of prenatal disturbance during the second trimester of life in schizophrenic patients. TFRC (Total Finger Ridge Count) and TABRC (Total a-b Ridge Count) were studied in a sample of 38 schizophrenic patients and 69 healthy individuals. A significant decrease of the a-b ridge count was found in patients compared to controls, with a significant linear trend across the population distribution (OR linear trend = 1.6; 95% CI = 1.0-2.4), indicating that the effect was not confined to a subgroup of cases with values in the lowest range. This finding was replicated in a second, larger sample (OR linear trend = 1.3; 95% CI = 1.0-1.8). The suggestion that a-b ridge count is associated with genetic risk for schizophrenia needs to be investigated further. TFRC did not distinguish between patients and controls. The a-b ridge count may be a continuous risk factor for later schizophrenia, pointing towards a disturbance occurring during the second trimester of prenatal life, a period of critical CNS growth.

Fetal brain development of twins assessed in utero by ultrasound: implications for schizophrenia

There is evidence that some forms of schizophrenia are due to alterations of in utero brain development. Given the concordance rate for schizophrenia in monozygotic twins is approx. 45%, it is not clear how a shared genetic predisposition for schizophrenia and a shared in utero environment might selectively lead to schizophrenia in one but not the other twin in a monozygotic twin pair. This study was undertaken to test the hypothesis that there is a difference in brain development between twins in a monozygotic twin pair that may contribute to the observed concordance rates for schizophrenia. Fetal ultrasound measures of brain (biparietal diameter, head circumference, ventricular width) and body size (femur length, abdominal circumference) obtained during the second trimester of fetal development were retrospectively analyzed in 41 monozygotic and 103 dizygotic twin pairs. In monozygotic twin pairs, there was a significant difference in measures of biparietal diameter, head circumference, and ventricular width, as well as in femur length and abdominal circumference, between twins. There was a similar difference in dizygotic twin pairs. These results indicate that in monozygotic twins, brain development is not identical. This difference in brain development may contribute to the observed concordance rates in monozygotic twins with schizophrenia.

[Importance of fetal sensorial capacity in the establishment of mother-child exchange during pregnancy]

The very early establishment of certain sensory faculties turns the fetus into a being capable of perceiving multiple stimuli. This perceptive capability participates in the many interchanges between the mother and her developing child. The good quality of psychoaffective communication between the mother and her child during pregnancy appears to be decisive for the fetal, perinatal, and later development of the child, especially for an harmonious brain growth. The risks of sensory and sensori-affective overstimulation are considered.

Minor physical anomalies in psychoses: associations with clinical and putative aetiological variables

This study of patients with functional psychoses set out to examine associations between minor physical anomalies (MPAs) and demographic, clinical, CT scan measures, and putative aetiological variables. 157 psychotic patients had minor physical anomalies assessed using a modified Waldrop scale. RDC diagnoses for these patients were: schizophrenia (n = 79), schizoaffective disorder (n = 31), mania (n = 24), major depression (n = 13), unspecified functional psychosis (n = 8), other organic psychosis (n = 2). 63 healthy white controls were also assessed with the modified Waldrop scale. Minor physical anomalies were not associated with any particular diagnosis. For white subjects, patients had significantly more MPAs than well controls. Anomalies of the palate were the most frequent item reported in patients and controls. For males, there was a weak association between the presence of MPAs and positive family history of a major psychiatric disorder. Those with MPAs required more frequent and longer psychiatric admissions, and showed impaired ability on a test sensitive to left parietal system function. Within the patient group, there were no associations between MPAs and gender, age at onset, negative symptoms, premorbid level of functioning, estimated premorbid intelligence, pregnancy and birth complications, and selected CT variables. Minor physical anomalies are found in a range of functional psychoses. There may be overlap between the various genes that predispose to psychiatric illness (especially in males) and those genes that predispose to developmental instability.

Viruses, schizophrenia, and bipolar disorder

The hypothesis that viruses or other infectious agents may cause schizophrenia or bipolar disorder dates to the 19th century but has recently been revived. It could explain many clinical, genetic, and epidemiologic aspects of these diseases, including the winter-spring birth seasonality, regional differences, urban birth, household crowding, having an older sibling, and prenatal exposure to influenza as risk factors. It could also explain observed immunological changes such as abnormalities of lymphocytes, proteins, autoantibodies, and cytokines. However, direct studies of viral infections in individuals with these psychiatric diseases have been predominantly negative. Most studies have examined antibodies in blood or cerebrospinal fluid, and relatively few studies have been done on viral antigens, genomes, cytopathic effect on cell culture, and animal transmission experiments. Viral research on schizophrenia and bipolar disorder is thus comparable to viral research on multiple sclerosis and Parkinson's disease: an attractive hypothesis with scattered interesting findings but no clear proof. The application of molecular biological techniques may allow the identification of novel infectious agents and the associations of these novel agents with serious mental diseases.

Schizophrenia epigenesis: past, present, and future

Sociopolitical and ideological attacks on the various genetically oriented programs of research into the causes of schizophrenia, even when well-motivated to prevent genetic discrimination in all its forms, endangers the enterprise. Although there have been no replicated successes in finding genes linked or associated to markers for schizophrenia yet, the solid foundation for the fact that genetic factors are importantly involved in the etiology of schizophrenia derives from replicated studies using the strategies of genetic epidemiology--families, twins, adoptees. The models to emulate in schizophrenia research should follow the paths of researchers on coronary artery disease, diabetes, and Alzheimer's disease. All are complex diseases with multifactorial and multigenic components. Even when the necessary genotype is present, it may not be expressed as clinical disease at the phenotypic level.

Obstetric complications as antecedents of schizophrenia: empirical effects of using different obstetric complication scales

The new McNeil-Sjöström Scale for obstetric complications (OCs), as well as scales of Lewis et al. (Schizophrenia: Scientific progress. Oxford University Press, 1989) and Parnas et al. (British Journal of Psychiatry, 140, 416-420, 1982), were applied to the OC histories of 70 singleton schizophrenics and 70 demographically-matched controls from the same hospital delivery series, using blindly assessed hospital pregnancy and birth record information. With the McNeil-Sjöström scale, schizophrenics were found to have significantly increased rates of OCs for the total reproduction, as well as for labor-delivery and the neonatal period but not for pregnancy. Significant increases in OCs in these schizophrenics were also found in scores produced by the Lewis et al. scale but not by the Parnas et al. scale. Further application of these three scales to OC data obtained through parental report for 23 monozygotic (MZ) twin pairs discordant and 10 pairs concordant for schizophrenia, as well as seven normal control MZ pairs, showed a significant difference in OC rates across the different twin pair groups, when assessed by the McNeil-Sjöström and Parnas et al. scales, but not by the Lewis et al. scale. The particular scoring system used in a study is thus of considerable importance not only for findings concerning OC histories of schizophrenics vs. controls, but also for the relationship between OCs and other presumed etiological factors in schizophrenia. Among the three scales, the McNeil-Sjöström scale provided the most sensitive assessment of OC history for schizophrenics.

Further evidence for anomalies in the hand-prints of patients with schizophrenia: a study of secondary creases

Finger and palm prints from 46 ICD-9 schizophrenic patients and 43 age and sex matched normal controls were examined independently and blind to diagnosis, by four raters. Seven prints were judged to have very high densities of secondary creases. These abnormal prints were all from the schizophrenic group. Patients with high densities of creases were more severely ill, having had more than five admissions to hospital and higher doses of neuroleptic medication. There was a trend for such patients to have had a complicated obstetric history and an earlier onset of their illness.

Preliminary evidence for an association between minor physical anomalies and second trimester neurodevelopment in schizophrenia

Two types of markers, dermatoglyphics and minor physical anomalies, have been used as indicators of problems with fetal neurodevelopment in schizophrenia. The degree to which these markers overlap is not known. While it is agreed that abnormal dermatoglyphics reflect early second trimester maldevelopment, the timing of the development of minor physical anomalies has not been determined. Forty-six schizophrenic patients received assessments for minor physical anomalies, dermatoglyphics (right-left ridge count asymmetry and total finger ridge count), and information processing. Higher scores for minor physical anomalies were associated with greater dermatoglyphic asymmetry. Patients who had both types of indicators (high minor physical anomalies and dermatoglyphic asymmetry) did not differ on information-processing measures from patients who had neither. On the basis of the timing of dermatoglyphic development (weeks 14-22 of gestation), the association between minor physical anomalies and dermatoglyphic asymmetry suggests that the relatively high rate of minor physical anomalies observed in schizophrenia can be considered to reflect at least second trimester maldevelopment.