Programmes of suicide prevention require for their planning accurate epidemiological surveys. Doubt has been cast on the accuracy of many existing surveys because of the realization that suicide is under-reported and because of the lack of consistency in the procedure for suicide ascertainment. Two studies are described in this paper which attempt to examine the problem. The first is part of an international study supported by the World Health Organization. In it, Denmark and England are compared, and it is shown that there are striking differences in suicide ascertainment procedure between the two countries. Next, on a blind basis, coroners and their opposite numbers in Denmark examine a sample of each other's case records. It is found that the Danes consistently report more suicides than do the English coroners on the same case material; thus considerable doubt is cast on the supposed difference in suicide rates between the two countries. In the second study, deaths by poisoning are examined for certain coroners' districts in England and Wales. It is shown that there is considerable variation from one district to another in the relative proportions of these deaths which achieve an accident, an open or a suicide verdict. This suggests that in England and Wales coroners may not be consistent in their suicide ascertainment criteria. Hypotheses attempting to account for differences in suicide rate based on such epidemiological surveys should be viewed with great caution.

The aims of this study were to compare the psychiatric morbidity occurring in the close relatives (N = 332) of patients showing nuclear forms of schizophrenia with that of a control group (N = 201), and to consider the findings in relation to the concept of the schizophrenic "spectrum' and to some genetic theories of schizophrenia. About one third of each group were interviewed by a psychiatrist using defined diagnostic criteria, and information of varying degrees of completeness was obtained about the remainder. After considering possible biases, it was concluded that the "spectrum disorders' most likely to be biologically related to schizophrenia were personality disorders of non-neurotic type, either alone or in combination with another diagnosis. The results, however, did not fit well with the model of dominant inheritance of schizophrenia and schizoid disease proposed by Heston (1970).

The hypothesis that schizophrenia and some non-psychotic abnormalities occurring in the close relatives are both manifestations of a unitary "schizoid state' due to a major dominant gene is further examined. Comparisons are made (1) of the observed and expected frequencies of the different types of parent mating; and (2) of the observed and expected risks among sibs in families with neither, or with one or both, of the parents abnormal. It is concluded that the results do not fit well with the model of inheritance of the schizoid state through a major dominant gene. Since some hereditary contribution in schizophrenia can be regarded as established, the excess of personality disorders and heavy drinking in the families is thought to be due to a combination of polygenic inheritance and environmental influences. The findings are regarded only as tentative, but suggest several hypotheses which could be tested.

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