To investigate changes in incidence of admissions for schizophrenia and related non-affective psychoses in North Wales.
Data from two epidemiologically complete cohorts of patients presenting for the first time to mental health services in North Wales between 1875–1924 and 1994–2010 are used in this study to map the incidence of hospital admissions for schizophrenia and non-affective psychoses.
The North Wales Asylum Denbigh (archived patient case notes) and the North West Wales District General Hospital psychiatric unit.
3168 patients admitted to the North Wales Asylum Denbigh between 1875 and 1924 and 355 patients admitted to the District General Hospital psychiatric unit between 1994 and 2010.
There was an increasing admission incidence for schizophrenia between 1875 and 1900, a higher admission rate in the 1990s for men, followed by a drop in rates of admission for both genders since 2006. Admission incidences switch from parity between the sexes in the historical period to a doubling of the admission rates for men compared with women in the modern period. This admission pattern differs from the admission patterns for affective psychoses or organic disorders.
There have been changes in the incidence of admissions for schizophrenia in North Wales.
This article investigates the incidence of schizophrenia and related psychoses in the 19th, 20th and 21st centuries.
It is a first report covering both historical and contemporary data drawn from one geographical area, with comprehensive patient ascertainment.
The data address longstanding questions concerning the incidence of schizophrenia in historical and contemporary periods.
This article is the first to report a specific rise in the admission incidence of schizophrenia in the 19th century. It reports a specific drop in the admission incidence of schizophrenia in the 21st century.
It demonstrates a switch in gender ratios for this illness in cohorts drawn from the same ethnic group and geographical area.
Strengths and limitations
This study has unique access to 19th and early 20th centuries asylum records.
The late 20th and early 21st century diagnosis are drawn from clinical consensus rather than administrative databases.
It is unlikely that the historical arm of this study can be replicated elsewhere. Confirmation of the findings will hinge on studies of 21st century incidence rates.
This is a study of hospital admission incidence and is therefore one step removed from the true incidence.