Seasonal fluctuation in birthweight in schizophrenia.

The birthweights of 450 schizophrenic patients born in 1971-1978 were compared with those of individually matched controls from the same birth cohort. Schizophrenics born in the second quarter of the year (April to June) had a significantly lower birthweight than their controls and this was not attributable to differences in the duration of gestation. Analogous proband/control differences were not found in 301 patients with affective psychoses, but there was a similar, much smaller, seasonal fluctuation in birthweight in the general population. These findings may be a clue both to the genesis of the "season of birth effect" and to the identity of the intrauterine influences contributing to the aetiology of schizophrenia. Folate deficiency may be implicated.

Exposure to sunlight, vitamin D and schizophrenia.

The hypothesis that vitamin D deficiency in pregnancy or early infancy may contribute to the aetiology of schizophrenia was tested by examining the relationship between population exposure to sunlight, which promotes the synthesis of vitamin D in the summer months, and the monthly rate of schizophrenic births in two large data sets--22,000 schizophrenic patients born in England or Wales between 1921 and 1960, and 8000 born in Scotland between 1932 and 1960. No convincing relationship could be found in either cohort.

The distinction between personality disorder and mental illness.

BACKGROUND: Proposals by the UK Government for preventive detention of people with 'dangerous severe personality disorders' highlight the unresolved issue of whether personality disorders should be regarded as mental illnesses. AIMS: To clarify the issue by examining the concepts of psychopathy and personality disorder, the attitudes of contemporary British psychiatrists to personality disorders, and the meaning of the terms 'mental illness' and 'mental disorder'. METHOD: The literature on personality disorder is assessed in the context of four contrasting concepts of illness or disease. RESULTS: Whichever of the four concepts or definitions is chosen, it is impossible to conclude with confidence that personality disorders are, or are not, mental illnesses; there are ambiguities in the definitions and basic information about personality disorders is lacking. CONCLUSIONS: The historical reasons for regarding personality disorders as fundamentally different from mental illnesses are being undermined by both clinical and genetic evidence. Effective treatments for personality disorders would probably have a decisive influence on psychiatrists' attitudes.

Obstetric complications and schizophrenia. Two case-control studies based on structured obstetric records.

BACKGROUND: Most previous case-control studies of obstetric complications in schizophrenia have been small scale and many have relied on retrospective information. AIMS: To determine which obstetric complications are more common in probands with schizophrenia than matched controls. METHOD: Two hundred and ninety-six probands with an in-patient diagnosis of schizophrenia who had been born in Scotland in 1971-74, and a further 156 born in 1975-78, were closely matched with controls and the incidence of obstetric complications in the two compared using obstetric data recorded in a set format shortly after birth. RESULTS: Not a single complication of pregnancy or delivery was significantly more common in the probands with schizophrenia than the controls in the 1971-74 birth cohort and only emergency Caesarean section and labour lasting over 12 hours were significantly more common in the schizophrenia probands in the 1975-78 cohort. CONCLUSION: The evidence that schizophrenia is associated with a raised incidence of obstetric complications is weaker than has recently been assumed.

Obstetric complications and affective psychoses. Two case-control studies based on structured obstetric records.

BACKGROUND: Unlike schizophrenia, little interest has been taken in the incidence of obstetric complications in affective psychoses. AIMS: To find out whether obstetric complications are more common in affective psychoses than matched controls. METHOD: Two hundred and seventeen probands with an in-patient diagnosis of affective psychosis who had been born in Scotland in 1971-74, and a further 84 born in 1975-78, were closely matched with controls and the incidence of obstetric complications in the two compared using obstetric data recorded in a set format shortly after birth. RESULTS: Abnormal presentation of the foetus was the only complication significantly more common in the affective probands in the 1971-74 birth cohort and artificial rupture of the membranes was the only event more common in the probands in the 1975-78 cohort. Both are probably chance findings. CONCLUSION: It is unlikely that the incidence of obstetric complications is raised in people with affective psychoses of early onset.

Annual variation in birth rate of people who subsequently develop schizophrenia.

BACKGROUND: Previous attempts to decide whether there is significant year-to-year variation in the birth rate of people who subsequently develop schizophrenia have given conflicting results, probably because of differences in the statistical methods employed. AIMS: To determine whether there is significant year-to-year variation in the birth rate. METHOD: Variation in the birth rate for the period 1921-1960 was studied in three separate national data sets--English, Danish and Scottish--using cubic splines to smooth the distribution curve before calculating residuals from a Poisson distribution. RESULTS: Over-dispersion was found in all three data sets, particularly in the Danish and Scottish data. However, the correlation between the sets of standardised residuals derived from the three data sets was only statistically significant for Denmark v. England. CONCLUSIONS: There was statistically significant year-to-year variation in the birth rate of people who subsequently developed schizophrenia in three countries in north-west Europe in the years 1921-1960. This is potentially a clue to the nature of the environmental determinants of schizophrenia, but better data will be needed before useful explanatory hypotheses can be generated and tested.

Obstetric complications and schizophrenia: a case control study based on standardised obstetric records.

BACKGROUND: There have been many reports of a higher incidence of 'obstetric complications' in the histories of schizophrenics than of controls, but because of the methodological shortcomings of most of these comparisons the relationship remains controversial. METHOD: Comprehensive records covering all psychiatric hospital admissions and all hospital deliveries in Scotland since 1971 made it possible to identify the obstetric records of people born in 1971-74 who were subsequently admitted to hospital with a diagnosis of schizophrenia, and then to compare their standardised obstetric records with those of closely matched controls. RESULTS: One hundred and fifteen schizophrenic/control pairs were compared. The former showed a highly significant (P < 0.001) excess of complications of both pregnancy and delivery. In particular, there was a significant excess of pre-eclampsia (10 v. 2) and of infants detained in hospital for neonatal care (18 v. 6). CONCLUSION: The raised incidence of obstetric complications often reported in people with schizophrenia is genuine and probably contributes to the aetiology of the condition.

Schizophrenic subjects with no history of admission to hospital.

It has often been assumed that all subjects with schizophrenia will eventually be admitted to hospital and therefore little bias is introduced by restricting research to hospitalized subjects. Using the Lothian Psychiatric Case Register, 66 subjects were identified who had been diagnosed in Edinburgh as suffering from schizophrenia between 1978 and 1989 but had no history of hospital admission by December 1991. This represented an adjusted average of 6.7% of the estimated annual rate of first diagnosis of schizophrenia: the proportion of such patients did not change over the period. Using a case-control design, the index cases were compared with a control group of schizophrenic patients who had been admitted to hospital within 3 months of diagnosis. At the time of diagnosis, the cases were generally less disturbed with lower levels of violent behaviour and less evidence of neglect or hallucinations. They had a longer duration of illness prior to diagnosis, were more often diagnosed by a consultant and unemployed. In a follow-up study of the index cases, 59 (89%) were traced, of whom 6 (10%) were deceased. The outcome of the illness was heterogeneous although the course was often chronic. The general practitioner provided most of the care they received. The small proportion of such patients suggests that their exclusion from most published series does not seriously bias our picture of the natural history of schizophrenia. Moreover, as there was no increase in the proportion over the period, first admission rates for schizophrenia in Scotland are a reasonable approximation to incidence rates.

Epidemiological evidence that maternal influenza contributes to the aetiology of schizophrenia. An analysis of Scottish, English, and Danish data.

The epidemiological evidence that the offspring of women exposed to influenza in pregnancy are at increased risk of schizophrenia is conflicting. In an attempt to clarify the issue we explored the relationship between the monthly incidence of influenza (and measles) in the general population and the distribution of birth dates of three large series of schizophrenia patients--16,960 Scottish patients born in 1932-60; 22,021 English patients born in 1921-60; and 18,723 Danish patients born in 1911-65. Exposure to the 1957 epidemic of A2 influenza in midpregnancy was associated with an increased incidence of schizophrenia, at least in females, in all three data sets. We also confirmed the previous report of a statistically significant long-term relationship between patients' birth dates and outbreaks of influenza in the English series, with time lags of -2 and -3 months (the sixth and seventh months of pregnancy). Despite several other negative studies by ourselves and others we conclude that these relationships are probably both genuine and causal; and that maternal influenza during the middle third of intrauterine development, or something closely associated with it, is implicated in the aetiology of some cases of schizophrenia.

The problem of detecting changes in the incidence of schizophrenia.

Despite reports of falling first-admission rates for schizophrenia in the UK and other Western countries, it would be rash to conclude that the incidence of schizophrenia is falling. An attempt was made to tackle the many methodological problems and sources of bias influencing the relationship between admission rates and incidence in an analysis of inception rates for schizophrenia and other psychoses in Edinburgh between 1971 and 1989. However it was calculated, the inception rate for schizophrenia fell significantly, but because there was evidence that diagnostic criteria for schizophrenia had narrowed between 1971 and 1989, and because a substantial and changing proportion of recorded first admissions were not true first admissions, it was impossible to conclude that the incidence of schizophrenia had fallen. Changes in the incidence of psychiatric syndromes are difficult to establish, particularly in retrospect, and future studies must pay more attention to the many possible confounding influences.

Relationship between the DSM-IV and the ICD-10.

The 10th revision of the International Classification of Diseases and Related Health Problems (ICD-10; World Health Organization, 1990) and the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) will both come into use in 1993 and be much more alike than the ICD-9 (World Health Organization, 1978) and the DSM-III (American Psychiatric Association, 1980). The American Psychiatric Association's controversial decision to publish a revision of the DSM-III in 1987 before setting up the Task Force to produce the DSM-IV impaired the association's ability to influence the format of the ICD-10, because by then major decisions had already been made by the World Health Organization. The DSM-IV will be more soundly based on a wider range of empirical data than any previous classification, national or international, and should not be revised again without compelling scientific reasons.

Unexplained fluctuations in the risk for schizophrenia by month and year of birth.

Variation in their year and month of birth was studied in the 13,661 schizophrenics born between 1914 and 1960 known to the Scottish Psychiatric Case Register. Year-to-year fluctuations in the number of schizophrenics per 10,000 live births were outside chance limits. So were month-to-month fluctuations between January 1932 and December 1960, and this was largely due to fluctuations in the numbers of schizophrenics born in February, March, April and May. Time-lagged correlations with mean monthly temperatures suggest that in these same four months the incidence of schizophrenia is influenced by temperature six months previously - the lower the temperature in the autumn the higher the incidence of schizophrenic births the following spring. If these findings can be confirmed in other data sets, they would suggest that some influence which varies consistently with season and temperature is contributing to the aetiology of schizophrenia and may exert its effects as early as the third or fourth month of foetal development.

Prophylactic lithium in puerperal psychosis. The experience of three centres.

At three centres, 21 women at high risk for puerperal psychosis were given prophylactic lithium carbonate late in the third trimester of pregnancy or immediately after delivery. Only two of the women had a recurrence of their psychotic illness while on prophylactic lithium. One woman given lithium during third trimester had an unexplained stillbirth. Although a larger sample in a carefully controlled study is still required, there now seems to be grounds for the use of prophylactic lithium immediately after delivery in women not breastfeeding who have previously suffered from either puerperal psychosis or bipolar disorder.