The neurodevelopmental basis of sex differences in schizophrenia

What have we learned from functional imaging studies in schizophrenia? The role of frontal, striatal and temporal areas

OBJECTIVES

Functional imaging technologies allow assessment of cerebral blood flow, cerebral metabolism, cellular metabolic processes, cerebral receptor density and occupancy. This review examines the contribution of such studies to our understanding of schizophrenia. The role of the frontal lobes, the basal ganglia, the temporal lobes and the neuronal circuits which connect them is examined with respect to this literature.

METHOD

All studies in schizophrenia using positron emission tomography, single photon emission computerised tomography, xenon studies, functional and spectroscopic magnetic resonance imaging formed the basis of this review. Only those studies published in English were reviewed.

RESULTS

The most consistent finding in schizophrenia has been that of hypofrontality, while the results of studies examining subcortical structures provide preliminary support for the concept of fronto-striatal dysfunction. Functional imaging has not yet provided consistent results in the study of temporal lobe function. Although receptor studies have shed light on the actions of antipsychotic medications, the findings for dopamine receptor numbers remain controversial. Spectroscopic and functional MRI remain in their infancy as research tools in schizophrenia.

CONCLUSIONS

Although there are significant methodological issues to be addressed, functional imaging technology is providing increasing insights into schizophrenia and its treatment. Future research will be truly multidisciplinary as it will require the collaboration of psychiatrists, imaging physicians, neuropsychologists and neuroscientists.

Drug strategies and treatment-resistant schizophrenia

OBJECTIVES

The aims of the paper are to review the notion of treatment resistance in schizophrenia and consider the factors important in determining non-responsiveness to standard neuroleptic treatment, and to review the strategies currently available in the treatment of such patients, including an evaluation of recently-introduced, novel drug treatments.

METHOD

A selective review of the literature relating to treatment resistance was undertaken using medline searches, followed by cross-checking for further articles identified in these references.

RESULTS

The various treatment approaches available are considered, including adjunctive treatment with lithium or carbamazepine. The risks and benefits of high dose antipsychotic treatment are discussed. The possible benefits and side-effects of new treatments, particularly the atypical neuroleptics, are also reviewed.

CONCLUSIONS

The reasons why a proportion of patients with schizophrenia fail to respond to standard neuroleptic treatment are ill-understood. Nevertheless, initial assessment should include identification of any factors that may be related to a patient's poor response, such as poor compliance, substance use or epilepsy. This may help to determine an appropriate treatment strategy. There is a need to be systematic and to ensure that patients be given an adequate trial of each treatment tested in terms of duration and dosage. The available evidence does not support the use of high doses of neuroleptics for the majority of patients. Adjunctive treatments, such as lithium, carbamazepine or benzodiazepines may be beneficial in non-responsive patients, particularly if certain target symptoms are present. Atypical neuroleptics, particularly clozapine, have proved particularly effective in non-responsive patients as well as those sensitive to the motor side-effects of standard drugs. However, the high risk of agranulocytosis with clozapine is a problem; also the drug and the necessary haematological monitoring are expensive. There are hints that some of the other, new, atypical neuroleptics have some benefit in non-responsive patients, but controlled studies are required.

Information processing, social skill, and gender in schizophrenia

The relationships among information processing, social skill, and gender in individuals with chronic schizophrenia were investigated. Although there were no gender differences in information processing, social skill, or negative symptoms, performance on information-processing tasks was related to various indices of social skill (e.g., paralinguistic skill) for female, but not male, inpatients. This pattern of results remained after statistical controls were applied for age, illness chronicity, and positive symptoms.

Psychopathological syndromes in the functional psychoses: associations with course and outcome

The aim of this study was to identify underlying dimensions of psychopathology in a cohort of patients with functional psychosis of recent onset, and to examine their prognostic value. Factor analysis of the psychopathological features of 166 consecutively admitted patients with functional psychosis of recent onset revealed seven psychopathological dimensions, which explained 63% of the variance. Five of these seven syndromes bore differential associations with subsequent treatment and illness course, independent of: (i) associations with DSM-III-R diagnosis; (ii) associations with other prognostic factors; and (iii) associations with the baseline values of outcome variables. The most striking associations were shown for an early and insidious onset syndrome with affective flattening, which predicted a more disabled course of illness on three of four outcome dimensions, and which was more common in males and unmarried individuals. A second syndrome, characterized by bizarre behaviour, inappropriate affect, catatonia, and poor rapport showed similar, slightly less striking, associations with illness course, as well as with poor pre-morbid social functioning. A third syndrome, characterized by positive psychotic symptoms was to a lesser degree associated with poorer outcome, whereas a fourth syndrome distinguished by manic symptomatology predicted a more benign illness course. A fifth syndrome identified by lack of insight predicted more time in hospital and admission under a section of the Mental Health Act during the follow-up period. A further finding was that dimensional representations of psychopathological features were considerably more useful than categorical representations (DSM-III-R and ICD-10) as predictors of illness course and treatment decisions.

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.

Adolescent schizophrenia: a methodologic review of the current neuroimaging and neuropsychologic literature

This paper reviews all relevant articles that reported structural neuroimaging or neuropsychological data in adolescent patients with schizophrenia. These papers were subsequently examined from a methodological perspective. Few papers have been written that have examined whether adolescent schizophrenia is associated with structural neuroimaging abnormalities or cognitive dysfunction. In these studies, major methodologic issues exist. Therefore, at present, firm conclusions cannot be made regarding the presence or absence of neuropsychologic dysfunction or structural neuroimaging abnormalities in this population. Attention to certain methodologic issues may improve future studies of this topic.

An association study of a neurotrophin-3 (NT-3) gene polymorphism with schizophrenia

Since abnormalities of brain development play a role in the aetiology of schizophrenia, growth factors, known to play a role in neurodevelopment, such as neurotrophin-3 (NT-3), are therefore candidate genes for this disorder. The A3/147 bp allele of a dinucleotide repeat polymorphism in the promoter region of the NT-3 gene has been reported as occurring more frequently in a sample of Japanese schizophrenics compared to controls. We have determined the frequency of alleles of this polymorphism in 175 Caucasian schizophrenic patients and 147 control subjects. The patient and control samples showed no significant deviation from Hardy-Weinberg equilibrium and, in a test of allalleles, the patients and controls did not differ significantly in allele frequencies. However, the male schizophrenics were more likely than male controls to have the A3/147 bp allele (P = 0.029).

Determinants of the extremes of outcome in schizophrenia

BACKGROUND

Although poor prognosis has been considered a defining characteristic of schizophrenia, long-term studies show marked heterogeneity of outcome.

METHOD

Assessments of positive and negative symptoms, premorbid and current IQ, and months of in-patient care made in an outcome study of 342 schizophrenic patients were categorised by severity. Determinants of these categorisations were sought from the historical variables available, using analysis of variance. Vignettes of patients with the best and worst symptomatic outcomes were then compared.

RESULTS

Negative symptoms were associated with early onset, male sex and poor academic record. Positive symptoms were associated with occupational decline. Cognitive decline was associated with occupational variables, and in-patient care with academic and occupational variables. The vignettes showed that good outcome was associated with family psychiatric history and poor outcome with unavailability of family history.

CONCLUSIONS

The findings support the view that the most malignant form of schizophrenia is neurodevelopmental, but poor outcome was clearly associated with family fragmentation.

The relationship of minor physical anomalies and other putative indices of developmental disturbance in schizophrenia to abnormalities of cerebral structure on magnetic resonance imaging

Minor physical anomalies, together with obstetric complications, family history, and handedness status, were assessed to explore putative neurodevelopmental disturbance(s) in patients with schizophrenia whose cerebral structure had been examined previously by magnetic resonance imaging. Minor physical anomalies were related to negative symptoms in males and to premorbid intellectual function in females, but not to ventricular volume; however, three patients with evident neurodevelopmental anomalies of the ventricular system showed prominent minor physical anomalies. In exploratory analyses, obstetric complications were associated with left ventricular asymmetry, and a positive family history with inverse profiles of asymmetry in males vs. females; non-right-handedness was associated with increased ventricular volume in males but with poorer premorbid intellectual function in females. This nexus of relationships and their gender specificities suggest early dysmorphogenesis in schizophrenia that is related to sexual dimorphism.

Gender and schizophrenia. Results of an epidemiologically-based family study

BACKGROUND

Gender may have a significant impact on the prevalence, age at onset, symptoms, course and outcome of schizophrenia, as well as on the pattern of psychopathology in relatives.

METHOD

We examined these questions in the Roscommon Family Study, in which the probands were epidemiologically sampled from a case registry and followed up an average of 15 years after onset. Face-to-face interviews were conducted with 86% of traceable living relatives.

RESULTS

The treated lifetime prevalence of DSM-III-R schizophrenia was 0.54 +/- 0.06% in men and 0.28 +/- 0.04% in women. No significant differences were seen in the age at onset, symptoms, course or outcome of schizophrenia. The risks for schizophrenia, schizophrenia spectrum disorders, affective illness and alcoholism were similar in relatives of male and female schizophrenic probands.

CONCLUSIONS

Gender has little impact on the presentation and course of schizophrenia in the west of Ireland. The familial liability to schizophrenia did not differ in affected men and women. No evidence was found that schizophrenia in women, compared to men, is, from a symptomatic or familial perspective, more closely related to affective illness. The substantial gender difference in the prevalence rate of schizophrenia in Ireland cannot be explained by women having a greater resistance to the familial predisposition to illness.

Differences in qualitative brain morphology findings in schizophrenia, major depression, bipolar disorder, and normal volunteers

This study examined the frequency and type of qualitative brain morphologic anomaly as a function of sex and diagnosis. Magnetic resonance imaging brain scans were evaluated by an experienced neuroradiologist blind to diagnosis. The scans of 325 individuals (108 schizophrenic, 20 schizoaffective, 27 major depressive, 20 bipolar and 150 healthy volunteers) were categorized into one of five groups: normal, hyperintensity signals, volume loss, ventricular anomaly or "other" abnormality. Schizophrenic men had significantly more morphologic anomalies, especially of the lateral ventricles than healthy male volunteers. Schizophrenic women did not differ from healthy women. Schizoaffective patients of both sexes, male depressive and female bipolar patients were also characterized by higher rates of brain anomalies. Independent of diagnosis, women were more likely than men to have hyperintensity signals among individuals with positive scan findings. The overall rate of brain morphologic anomalies is significantly higher among male schizophrenic patients than healthy volunteers; this is not specific to male schizophrenics, however, suggesting a global sex effect. Type of anomaly may differ by sex and give us clues about sex differences in the pathophysiology of psychopathology.

Schizophrenia: gender, family risk, and plasma homovanillic acid

Plasma homovanillic acid concentration was assessed in 60 young schizophrenic patients, with and without first-degree relatives with schizophrenia, before treatment, and 3 days after starting haloperidol treatment. The baseline concentration of homovanillic acid in plasma was no different in the two groups before treatment; it was, however, significantly higher in the patients with relatives than in those without relatives diagnosed of schizophrenia after 3 days of haloperidol treatment.

Cerebral hemispheric asymmetry revisited: effects of handedness, gender and schizophrenia measured by radius of gyration in magnetic resonance images

Abnormal patterns of cerebral hemispheric asymmetry have been inconsistently reported in association with schizophrenia. Radius of gyration (Rg) is a measure of the mean dispersion of points in a radially organized structure about that structure's centre of gravity. We developed computerized methods for estimating Rg of the magnetic resonance image (MRI) boundary between cortex and subcortex, and applied these methods to measurement of cerebral hemispheric asymmetry in 37 schizophrenics (SZs) and 30 controls (CONs). In right-handed CONs, Rg of right brain boundaries was significantly greater than Rg of left brain boundaries; in left-handed CONs, Rg of left brain boundaries was significantly greater than Rg of right brain boundaries. In right-handed males (both SZ and CON) there were significant differences in Rg between hemispheres; whereas in females (both SZ and CON), there were no such differences. Right-handed male SZs (N = 26) were distinguished by reversal of the right-handed male CON pattern of interhemispheric difference in Rg, and by global reduction in Rg of right brain boundaries. These was no evidence for significant abnormality of Rg in right-handed female SZs (N = 7). There findings suggest an important interactive effect of gender and schizophrenia on lateralized cerebral structure.

Psychotic states arising in late life (late paraphrenia). The role of risk factors

BACKGROUND

This study explored the association between 'late paraphrenia' and various risk factors such as female gender, sensory impairment, marital status, positive family history of psychoses, and the presence of abnormal neurological signs. It was hypothesised that patients would show significantly more abnormal neurological signs than controls.

METHOD

Inclusion criteria for the diagnosis of late paraphrenia were fulfilled by 47 patients, including in-patients, out-patients, day-patients, and those living in the community. Thirty-three age-, sex-, education-, and premorbid IQ-matched elderly controls were recruited from luncheon clubs in Southwark and Lambeth (London, UK). A scale for the assessment of neurological soft and hard signs was developed for this study. The Abnormal Involuntary Movement Scale (AIMS) and the Tardive Dyskinesia Rating Scale (TDRS) were also used.

RESULTS

There was a high female-to-male ratio (42:5), and a fourfold increase in the risk of patients having hearing impairment (odds ratio = 4.15, Clodds = 1.36 to 12.63). There was no difference between the two groups in visual difficulties nor in marital status. Patients were approximately ten times more likely to be living on their own (odds ratio = 10.61; Clodds = 3.59 to 31.33) and 16 times more likely to be considered socially isolated (odds ratio = 16.65; Clodds = 5.39 to 51.40). There was no difference between patients and controls in frequency of schizophrenia-like family history. Patients were more likely than controls to exhibit neurological soft signs (z = 4.70; P < 0.001; Cld = 4.61 to 9.63). The presence of abnormal involuntary and tardive dyskinesia movements was associated with the use of antipsychotic medication.

CONCLUSION

Women appear to run a greater risk of developing late paraphrenia, especially those who are socially isolated and present with associated hearing impairment. The increased presence of neurological soft signs among patients indicates that brain disease may be a critical factor in the development of psychotic symptoms in late life.

Course of patients diagnosed as having schizophrenia during first episode occurring under age 18 years

Of 118 child and adolescent schizophrenic patients (ICD-9: 295.x; mean onset age 16.0 years), 97 (82.2%) could be completely investigated at follow-up (mean interval 7.4 years; mean age 23.1 years). At follow-up 30% of the patients were semi-dependent or dependent, 72% still required psychiatric treatment, 44% were at least moderately impaired with regard to educational/occupational functions and 58% with regard to social functions; 73% had experienced at least one further schizophrenic episode. Comparison with schizophrenia beginning in adulthood showed that the impairment in social function was much greater in the younger group of patients. These results support the belief that schizophrenic psychoses starting in adolescence have a worse outcome than those beginning in adulthood. The most efficient indicators for a worse outcome were long duration of inpatient treatment at first admission, a high number of symptoms and low social competence at discharge.

1H-magnetic resonance spectroscopy of the left temporal and frontal lobes in schizophrenia: clinical, neurodevelopmental, and cognitive correlates

Twenty eight schizophrenic patients and 20 normal volunteers underwent proton magnetic resonance spectroscopy (MRS) on the left temporal and frontal lobe regions. Male patients showed a significant reduction in frontal but not temporal n-acetylaspartate (an intraneuronally distributed metabolite) in comparison with either male controls or female patients; frontal choline was raised in male patients relative to these groups. Putative neurodevelopmental indices, including obstetric complications, family history of schizophrenia, and minor physical anomalies, proved unrelated to MRS resonances. However, multiple aspects of memory function in patients were related to temporal but not frontal creatine, a pattern that was not apparent among controls. These MRS findings complement some previous structural MRI studies and much clinical and epidemiological evidence of important gender differences in schizophrenia. The findings also suggest that memory dysfunction in patients with schizophrenia may be associated with a particular pattern of temporal lobe metabolism on MRS.

Schizophrenia in Croatia: age of onset differences between males and females

The age of disease onset, the age at first admission and the age of first admission with a schizophrenia diagnosis were determined in a sample of 679 patients (356 males and 323 females) representing 8069 schizophrenics hospitalized in Croatia in the 1962-1971 period and followed up in an epidemiologic field study until 1991. Male and female patients were not found to differ significantly either in the average age of schizophrenia onset or age at first admission. In the majority of females the disease started at a slightly earlier age than in males, which might be due to the general biological and psychosocial differences between males and females. The age of females at first admission with a schizophrenia diagnosis was significantly higher than that of males. The differences between the schizophrenic males and females in the length of the preadmission period and diagnostic process, as well as in mortality, may contribute cumulatively to the recording of onset for female schizophrenics at a higher age in comparison to male schizophrenics.

HLA-DR types in Japanese schizophrenics: analysis by group-specific PCR amplification

An association of HLA-DR8 and DR1 with DSM-III schizophrenia has been reported in Japan (Miyanaga et al. (1984) Biol. Psychiatr. 19, 121-129). To further investigate this preliminary finding, we compared HLA-DR types in 44 unrelated Japanese schizophrenics (DSM-III-R) with those in 51 unrelated, healthy Japanese volunteers. Group-specific PCR amplification was used in the determination of HLA-DR in the patients. No significant difference was observed in the frequency of any DR types between patients and controls, after statistical correction for multiple testing. However, the frequency of DR1 in our patients (23%) and controls (10%) was almost the same as those in the previous report (22% vs. 10%), which means that there is a suggestive trend which could become significant if numbers were larger. It is argued that an exact determination of HLA-DR by DNA typing is important in current HLA studies of schizophrenia.

Are schizophrenic men at higher risk for developmental deficits than schizophrenic women? Implications for adult neuropsychological functions

This study tested the hypothesis that schizophrenic men would be at a greater risk than schizophrenic women for exhibiting a history of developmental problems in childhood and would exhibit more neuropsychological deficits as adults. The study was a secondary analysis of data that were collected in 1981-83. The sample consisted of 49 DSM-III schizophrenic patients (57% male/43% female), who were generally in the early stages of the disorder. All subjects received a neurodevelopmental and clinical/diagnostic interview and a neuropsychological battery of tests, including measures of intelligence, abstract reasoning, memory, sustained attention, executive function, language skills, and motor ability. Latent class analysis was used to identify gender differences in subclasses of schizophrenia. The groups were then compared on neuropsychological function. Results indicated that schizophrenics with histories of early developmental problems exhibited significantly more neuropsychological dysfunction as adults than did other schizophrenics, and they were more likely to be men. Impairment in this group was evident in the areas of verbal ability, attention, abstraction, motor function, and verbal and nonverbal learning and memory, with verbal tasks being relatively more impaired.

Is there a sex-specific difference in onset age of schizophrenia that started before age 18?

Schizophrenia in male adults starts on average 4-5 years earlier than in females. The lifetime risk for both sexes is equal. It is still unknown, whether this observation is also valid for children and adolescents. This question was examined in the present study by means of data from the literature and a study of our own (n=118). From a total of 28 studies, only eight used standardized diagnostic criteria and confined the age range from 11 to 18 years. Neither the data of these eight studies nor those of the Mannheim-Study indicate an earlier onset of schizophrenia in male adolescents. Possible reasons are discussed.

Age at onset, sex, and familial psychiatric morbidity in schizophrenia. Camberwell Collaborative Psychosis Study

BACKGROUND

Although a genetic component in schizophrenia is well established, it is likely that the contribution of genetic factors is not constant for all cases. Several recent studies have found that the relatives of female or early onset schizophrenic patients have an increased risk of schizophrenia, compared to relatives of male or late onset cases. These hypotheses are tested in the current study.

METHOD

A family study design was employed; the probands were 195 patients with functional psychosis admitted to three south London hospitals, diagnosed using Research Diagnostic Criteria (RDC), and assessed using the Present State Examination (PSE). Information on their relatives was obtained by personal interview of the mother of the proband, and from medical records. Psychiatric diagnoses were made using Family History-Research Diagnostic Criteria (FH-RDC), blind to proband information.

RESULTS

There was a tendency for homotypia in the form of psychosis within families. The lifetime risk of schizophrenia in the first degree relatives of schizophrenic probands, and the risk of bipolar disorder in the first degree relatives of bipolar probands, were 5-10 times higher than reported population risks. Relatives of female and early onset (< 22 years) schizophrenic probands had higher risk of schizophrenia than relatives of male and late onset schizophrenic probands. However, this effect was compensated in part by an excess of non-schizophrenic psychoses in the relatives of male probands.

CONCLUSIONS

These results suggest a high familial, possibly genetic, loading in female and early onset schizophrenia, but do not resolve the question of heterogeneity within schizophrenia.

The Nithsdale Schizophrenia Surveys. XII. 'Neurodevelopmental' Schizophrenia: a search for clinical correlates and putative aetiological factors

BACKGROUND

The aim was to examine in a population of schizophrenic patients the clinical correlates of 'neurodevelopmental' schizophrenia and their relationship to putative aetiological factors.

METHOD

Premorbid social adjustment, premorbid schizoid and schizotypal personality traits, and the obstetric history of 40 schizophrenic patients and their 102 sibs were assessed through interviews with their mothers. Patients' premorbid level of intelligence was assessed by the National Adult Reading Test and current symptoms by the Positive and Negative Syndrome Scale and the Subjective Deficit Syndrome Scale.

RESULTS

Patients had more schizoid and schizotypal traits than their sibs. They showed a deterioration in social adjustment between childhood and adolescence; sibs' social adjustment improved. There were statistically significant associations between current negative schizophrenic symptoms, premorbid deterioration in social adjustment, and schizoid and schizotypal personality traits, and between an early age of onset of illness and the same premorbid assessments. There was no evidence that patients with a family history of severe mental illness leading to hospitalisation, or a history of definite obstetric complications, had poorer premorbid functioning or more severe current symptoms.

CONCLUSIONS

We have confirmed clinical correlates of 'neurodevelopmental' schizophrenia but found no association between these and obstetric complications or a family history of severe mental disorder.

Childhood-onset schizophrenia: timely neurobiological research

OBJECTIVE

To review timely research on childhood-onset schizophrenia in view of advances in biological research on, and neurodevelopmental theories of, the later-onset disorder.

METHOD

Research issues are outlined including further clarification of ICD- and DSM-defined childhood schizophrenia, and differentiation from autism "spectrum" and other subtle, chronic developmental disorders. Key neurobiological advances are reviewed for which child studies are relevant and feasible.

CONCLUSION

It is anticipated that narrowly defined childhood-onset schizophrenics will constitute a predominantly male population. A high rate of family illness or chromosomal and/or brain developmental abnormalities, which will be instructive regarding the pathophysiology of later-onset schizophrenia, is expected.

Which patients with non-affective functional psychosis are not admitted at first psychiatric contact?

BACKGROUND

We wished to explore the sociodemographic and clinical characteristics associated with admission to hospital in patients with a non-organic non-affective psychosis.

METHOD

Subjects were 484 first-contact patients with a non-affective functional psychosis from an inner-city catchment area over 20 years from the mid-1960s. Sociodemographic and clinical characteristics associated with admission to hospital were analysed.

RESULTS

Around 20% of patients were not admitted, and the proportion did not change significantly over the years. Ethnicity, sex, and marital and employment status did not predict admission. Factors associated with admission included police involvement, and violence to self or others. A diagnosis of schizoaffective disorder, and persecutory delusions, auditory hallucinations, and bizarre behaviour were all more common in patients admitted to hospital.

CONCLUSIONS

The study indicates biases which might arise in research based exclusively on patients admitted to hospital.

A reconsideration of the relationship between cerebral structural abnormalities and family history of schizophrenia

In a study of 229 schizophrenic patients for whom reliable family history information was available, ventricular size and incidence of ventricular enlargement were found to be greater in male cases without a family history of schizophrenia. A significant sex by family history interaction on cerebral ventricular dimension was detected. The age-corrected morbid risk for schizophrenia was lower among first degree relatives of male probands with ventricular enlargement vs. those with normal ventricles, but similar in relatives of females with and without ventricular enlargement. On the other hand, no association was found between family history and degree of cortical atrophy. A meta-analysis of published studies on the issue revealed 20% larger ventricles in patients without any known genetic predisposition for schizophrenia.

Neurotrophin-3 gene polymorphism associated with schizophrenia

The recent possible neurodevelopmental etiology of schizophrenia makes the neurotrophin-3 (NT-3) gene an interesting candidate locus. We studied the allelic distributions of dinucleotide repeat polymorphism at the NT-3 gene locus in 70 patients with schizophrenia and in 70 controls. A highly significant difference between the two groups was observed at the allele A3. Even Bonferroni's correction was used, the difference was still significant. Individuals with homozygous or heterozygous for the allele A3 had a 2.4-fold increased risk of schizophrenia. Determination of NT-3 genotype may help to identify those at greater risk of schizophrenia. Furthermore, this finding supports evidence implicating neurodevelopmental deficit in the pathogenesis of this disorder.

Phenomenology, demography and diagnosis in late paraphrenia

One hundred and one patients with late paraphrenia were examined using the Present State Examination. The established high prevalence rates of female gender, the unmarried state and sensory impairment were confirmed. All of the symptoms of schizophrenia, with the exception of formal thought disorder, were found in the subjects with approximately the same prevalence as reported in schizophrenics with a symptom onset in younger life. The presence of visual hallucinosis was significantly associated with visual impairment, but the same association was not found between auditory hallucinations and deafness. Mean age at onset of symptoms was high at 74.1 years. Using ICD-10 diagnostic criteria the patients were categorized as schizophrenia (61.4%), delusional disorder (30.7%) and schizoaffective disorder (7.9%). Patients in these diagnostic categories differed in their pre-morbid IQ estimations, current cognitive state measured by the Mini-Mental State Examination and in the number of scored positive psychotic PSE symptoms and their systematization of and preoccupation with delusions and hallucinations. There were no significant differences between the patients in the ICD-10 schizophrenia and delusional disorder groups in terms of age at symptom onset, sex ratio, response to treatment, being unmarried, the presence of insight or sensory impairment. The high degree of clinical similarity between patients with late paraphrenia combined with the inability of ICD-10 to define diagnostic subgroups that correspond to patient clusters derived from clinical symptoms or which are meaningfully different from each other in terms of demographic and prognostic factors provide a strong argument for the retention of late paraphrenia as the most appropriate diagnosis for such patients.

Is schizophrenia due to excessive synaptic pruning in the prefrontal cortex? The Feinberg hypothesis revisited

Several lines of evidence support the notion that a substantial reorganization of cortical connections, involving a programmed synaptic pruning, takes place during adolescence in humans. A review of neurobiological abnormalities in schizophrenia indicates that the neurobiological parameters that undergo peripubertal regressive changes may be abnormal in this disorder. An excessive pruning of the prefrontal corticocortical, and corticosubcortical synapses, perhaps involving the excitatory glutamatergic inputs to pyramidal neurons, may underlie schizophrenia. A reciprocal failure of pruning in certain subcortical structures, such as lenticular nuclei, may also occur. Several developmental trajectories, related to early brain insults as well as genetic factors affecting postnatal neurodevelopment, could lead to the illness. These models would have heuristic value and may be consistent with several known facts of the schizophrenic illness, such as its onset in adolescence and the gender differences in its onset and natural course. The relationship between these models and other etiological models of schizophrenia are summarized and approaches to test relevant hypotheses are discussed.

Schizophrenia: sex and familial morbidity

Several recent studies have found a greater risk of schizophrenia among the relatives of female schizophrenic probands than the relatives of male schizophrenic probands. These results are contradictory to those of earlier studies. The current investigation, using family data collected in the 1950's and 1960's in Sweden, did not find a difference in the risk of schizophrenia among the relatives of male and female schizophrenic probands. However, significantly more relatives of female probands than relatives of male probands had manic-depressive psychosis. These findings suggest that the earlier studies may have included some female schizophrenic probands who would be classified as having manic-depression by modern criteria.

Gender differences in age at onset of schizophrenia

Numerous studies have found that male schizophrenic patients have earlier ages at onset than females. However, none of these studies have corrected the observed ages for known gender differences in the age distribution of the population. Using a pre-existing data set, we applied a non-parametric method to correct the male and female distributions of observed age at onset for sex-specific age distributions. The distributions of observed age at onset indicated earlier onset among males. After correction, the age-at-onset distributions shifted toward older ages, but the difference between males and females remained statistically significant. Thus, gender differences in the age at onset of schizophrenia are not artefactual.

The criminal careers of incident cases of schizophrenia

We present a population-based, longitudinal study of all incident cases (N = 538) of schizophrenia in the London Borough of Camberwell between 1964 and 1984. Cases were selected from the Camberwell Cumulative Psychiatric Case Register. Case-notes were obtained, and further classified using a computerized operational check list for rating psychotic illness. Cases are not restricted to hospital discharges, as in previous studies, and account is taken of time at liberty to offend. In order to test the hypothesis that schizophrenia makes an independent contribution to criminality over other mental disorders, controls were chosen to be representative of nonschizophrenic mental disorders matched for age, sex and period. The rate of conviction is increased in women with schizophrenia compared to other mental disorders for most offence categories (rate ratio = 3.3). In men overall rates do not differ (rate ratio = 1.03), although there is an interaction between gender, schizophrenia and ethnicity, with young black men with schizophrenia being most at risk. The rate ratio for violent offences in men with schizophrenia is 3.8, confirming recent studies from Sweden. Subjects with schizophrenia were more likely to acquire any criminal record than those with other mental disorders. The rate of lifetime conviction was greater in those with schizophrenia than either a sample of working-class boys from the same area followed by Farrington & West, or National data. The risk of first conviction is increased by schizophrenia, unemployment, ethnic group, substance abuse and low social class, and decreased by being employed, married, female and older age of onset. Adjustment using survival analysis showed that schizophrenia made a small independent contribution to the risk of acquiring a criminal record (hazard ratio = 1.4) but gender, substance abuse, ethnicity and age of onset were more substantial. Previous criminality was the strongest independent association of post-illness conviction, with schizophrenia only a trend. Although subjects with schizophrenia were more likely to acquire a criminal record, criminal careers began later and were shorter than those of the controls. The risk of criminality increased throughout the study period, but suggestions of a specific increase in those with schizophrenia as a result of changes in community care were not confirmed. These results confirm that women with schizophrenia are at increased risk of acquiring a criminal record, but the effect in men is for violent convictions only. The strongest associations of criminal conviction remain those recognized in non-schizophrenic subjects.

Testosterone modulates mesolimbic dopaminergic activity in male rats

Male rats were castrated before puberty. When they were adult, the activity of their mesolimbic dopamine system was tested by ventral striatum microdialysis. Amphetamine injections increased dopamine more in castrated rats than in normal rats. This exaggerated response was attenuated by testosterone replacement therapy. The mechanism by which androgens modulate the activity of the mesolimbic dopamine system is discussed.

Magnetic resonance imaging findings of amygdala-anterior hippocampus shrinkage in male patients with schizophrenia

Recent magnetic resonance imaging (MRI) studies found abnormalities of medial temporal lobe and basal ganglia structures. We used an inversion recovery (IR) protocol with the assistance of the Talairach atlas to identify neuroanatomical regions of interest in 19 male schizophrenic patients and 14 matched control subjects. The patient group showed smaller amygdala-hippocampus volume as compared with normal control subjects. This finding was more pronounced for the left side, although no diagnosis X side interaction was present. Third ventricle volume was also enlarged in schizophrenic patients. Trends toward an overall reduction of basal ganglia (striatum and lenticular nucleus) and limbic structures and toward an increase in ventricle-brain ratio were also seen. The study confirms previous evidence of mesial temporal lobe shrinkage, more evident on the left side in a group of relapsing noninstitutionalized male schizophrenic patients.

Evidence for a gender-specific decline in the rate of schizophrenia in rural Ireland over a 50-year period

The issue of whether the incidence rate of schizophrenia may have declined over recent decades has generated considerable controversy. This study sought to ascertain and interview all patients who satisfied contemporary diagnostic criteria for schizophrenia within a defined and unusually homogeneous region of rural Ireland having a total population of 25,178 people; morbid risk for schizophrenia was then examined by quinquennia of birth from 1920-24 to 1965-69. Morbid risk appeared essentially constant for persons born between 1920 and 1939 but fell by 37% for those born between 1940 and 1969, the fall being considerably more prominent in females (-56%) than in males (-19%). Attention is focused on sexual dimorphism in cerebral development and on temporal changes in endogenous or exogenous factors that influence the rate of occurrence of schizophrenia in females.

A typological model of schizophrenia based on age at onset, sex and familial morbidity

We investigated the age at onset distributions of schizophrenia in men and women and the relationship of age at onset and sex to the familial rates of schizophrenia and manic-depression in data from a Swedish family study of 270 schizophrenic probands. On the logarithmic scale, the age at onset distribution of schizophrenia in both male and female relatives was bimodal, suggesting that broadly defined schizophrenia may be a mixture of 2 (probably related) disorders. The risk of schizophrenia in relatives decreased as a function of the age at onset of the proband, irrespective of the sex of the proband or relative. In contrast, the risk of manic-depression was significantly higher in relatives of female probands with an age at onset in the twenties than in relatives of female probands with earlier or later onset, or in relatives of male probands. This suggests a third disorder related to affective psychosis, with an intermediate age at onset and female preponderance.

The subtyping of schizophrenia in men and women: a latent class analysis

Latent class analysis on an epidemiologically based series of 447 first contact patients with a broad diagnosis of schizophrenia revealed evidence for two subtypes: a 'neurodevelopmental' type characterized by early onset, poor pre-morbid social adjustment, restricted affect and a male:female ratio of 7:3; and a 'paranoid' type characterized by later onset, persecutory delusions and an almost equal sex ratio. A third 'schizoaffective' subtype, whose existence was less clear cut, was almost entirely confined to females and characterized by dysphoria and persecutory delusions, and had negligible familial risk of schizophrenia. The aetiological, biological and clinical significance of this typology remains to be tested.

Higher morbidity risk for schizophrenia in males: fact or fiction?

Male to female ratios in published annual incidence rates for schizophrenia range from 0.70 to 3.47. These variations between studies are attributed to differences in sampling, diagnostic criteria, design characteristics, and methods of calculation, which limit the quality of the studies. In an effort to overcome these shortcomings, we collected a comprehensive sample of 392 consecutive first admissions with a diagnosis of schizophrenia or a similar disorder out of a population of 1.5 million in a central region of western Germany. In this large representative sample, no significant gender differences in the incidence of schizophrenia could be detected regardless of different diagnostic definitions.

D2 dopamine receptor binding in the basal ganglia of antipsychotic-free schizophrenic patients. An 123I-IBZM single photon emission computerised tomography study

We used SPECT to examine striatal D2 receptor binding in 20 antipsychotic-free DSM-III-R schizophrenic patients and 20 age- and sex-matched normal controls. Dynamic single-slice SPECT, at a slice chosen to include the basal ganglia, began immediately following intravenous injection of 185 MBq of 123I-IBZM. A semiquantitative approach was used to generate indices of specific D2 receptor binding in the basal ganglia. There was no overall elevation of D2 receptor binding between patients and controls. A male sex-specific left lateralised asymmetry of striatal D2 receptor binding was found in the patient group. Age-dependent decline of striatal D2 receptors was confirmed in controls, but not in patients. These results suggest that alterations in striatal D2 receptor distribution and density do occur in schizophrenia, and possibly reflect wider disruptions in prefrontal-striatal-limbic circuits.

Sex differences in schizophrenia: a demographic, symptomatic, life history and genetic study

Twenty-one male and 32 female inpatients who met the criteria of schizophrenia according to the Research Diagnostic Criteria were compared for demographic, symptomatic, life history, and genetic variables. Female schizophrenics were marginally less likely to have auditory hallucinations; They were more likely to have early loss experiences (either bereavement or separation from a parent) before the age of 16. No other differences were found between the men and women.

Does prenatal influenza divert susceptible females from later affective psychosis to schizophrenia?

We examined the relationship between influenza epidemics and the number of schizophrenic and affective psychotic individuals born each month between 1938 and 1965 in England and Wales. Increased death rates from influenza were followed 5 months later by a significant increase in schizophrenic births and a concurrent fall in the number of births of affective psychotic individuals. When the sexes were examined separately, both the positive effect of influenza on schizophrenic births and its negative effect on affective psychotic births were evident for females but not for males. Furthermore, during February to June in high influenza years, there was an inverse relationship between the number of female schizophrenic and affective psychotic births. The explanation for these surprising findings may be that prenatal exposure to influenza impairs the neurodevelopment of some females with a predisposition to affective psychosis, in such a way that their later illness shows schizophrenic rather than affective features.

Persistence of the decline in the diagnosis of schizophrenia among first admissions to Scottish hospitals from 1969 to 1988

Age-standardised rates were calculated for first admissions to hospital in Scotland with ICD-9 diagnoses of schizophrenia, affective psychoses, paranoid psychoses, reactive psychoses and depressive neuroses (ICD-9 295, 296, 297, 298 and 300.4) for the period 1969-88. First-admission rates for schizophrenia declined by an average of 3.3% per year in males and 4.4% per year in females over the period. The first-admission rate in males in 1988 was 8.4/100,000 (57% of 1969 rate) and in females was 4.8/100,000 (43% of 1969 rate). Rates for depressive neuroses, affective psychoses, reactive psychoses and combined psychoses also fell. Rates for mania rose, as did those for paranoid states in males. The decrease in first-admission rates is likely to reflect a true decrease in the incidence of schizophrenia over the period. The decline was unlikely to be accounted for by diagnostic change because there was no reciprocal increase in any other diagnosis sufficient to account for the change, and the rates for combined psychoses also decreased. There was evidence that rates for schizophrenia declined to a greater extent in younger age groups, especially in females. This could imply the presence of a birth cohort effect.

Schizophrenia in Nottingham: lifelong residential mobility of a cohort

The lifetime geographical mobility of a group of 67 patients suffering from schizophrenia was investigated and related to the ecological structure of the city of Nottingham, where they first presented between 1978 and 1980. The study aimed to investigate the processes leading to a threefold rate of schizophrenia in the most socioeconomically deprived area of the city compared to the area of least deprivation. Results suggest that this skewed distribution begins early in the lives of the patients and is well established at least five years before initial contact with the psychiatric services.

A comparative study of 470 cases of early-onset and late-onset schizophrenia

The presence or absence of 22 schizophrenic symptoms was recorded with the age at onset of illness in 470 patients with non-affective, non-organic psychoses. Positive and negative formal thought disorder, affective symptoms, inappropriate affect, delusions of grandiosity or passivity, primary delusions other than delusional perception, and thought insertion and withdrawal were all more common in early-onset cases (age at onset 44 years or less; n = 336). Persecutory delusions with and without hallucinations, organised delusions, and third-person, running commentary and accusatory or abusive auditory hallucinations were all more common in late-onset cases (age at onset 45 years or more; n = 134). There was no difference between cases of early and late onset in the prevalence of delusions of reference, bizarre delusions, delusional perception, or lack of insight. We conclude that although there are clinical similarities between cases of schizophrenia with early and late onset, there are sufficient differences between them to suggest that they are not phenotypically homogeneous.

Gender specificity of geographical variation in morbid risk for schizophrenia in rural Ireland

The morbid risk for schizophrenia was determined separately for men and women within each of 36 contiguous district electoral divisions of a rural Irish county in which all cases of schizophrenia satisfying DSM-III-R criteria had been sought. The distribution of morbid risk values for men (0.0-19.2 per 1000) was in accordance with a statistical model for random occurrences in space, while for women (0.0-38.3 per 1000) it deviated markedly from such a model; thus, morbid risk for schizophrenia showed very prominent geographical variations in women, but not in men. These findings may have a basis in factors that can show both spatial inhomogeneity and gender specificity in their consequences for schizophrenia.

Puberty and the onset of psychosis

According to the neurodevelopmental hypothesis of schizophrenia, maturational events in the brain at puberty interact with congenital defects to produce psychotic symptoms. As girls reach puberty at a younger age than boys, we predicted that (i) females would show earlier onset of psychotic illness arising around puberty, and (ii) onset of psychosis in females would be related to menarche. Analysis of epidemiological data regarding admission to psychiatric units in (a) England over the period 1973-1986, (b) France over the period 1975-1980, as well as examination of 97 psychotic adolescents referred to an adolescent unit over a 14 year period, supported both these propositions.

Age of onset in schizophrenia: relations to psychopathology and gender

This retrospective study evaluated differences between patients with first manifestation of schizophrenic psychosis (ICD 295) or paranoid syndrome (ICD 297) between the ages of 18 and 23 or 40 and 63 years. Gender-specific variations in psychopathology were also examined. The numerous analyses of variance gave few significant differences. Patients with a late onset of the disease scored higher on depressive and autonomic syndrome scales at admission, whereas patients with an early onset showed more psychosocial impairment at discharge and their stay in hospital was longer. Among schizophrenic patients only (ICD 297 excluded), only the higher score for autonomic syndrome of the older patients at admission was confirmed. Men were more apathetic at admission and discharge than were women. Excluding patients with a paranoid syndrome, these differences were again significant. Moreover, schizophrenic men had higher depressive and psycho-organic syndrome scores at discharge. The demonstration of only marginal differences between early- and late-onset schizophrenia does not support the assumption that age of onset markedly influences psychopathology.