Family history of psychiatric disorders and age at first contact in schizophrenia: an epidemiological study

Background The risk for schizophrenia has been associated with a family history of this and other psychiatric disorders. The relationship between age at first contact and family history of psychiatric illness is not certain. Aims To estimate the risks for schizophrenia associated with a range of psychiatric diagnoses in family members and to investigate the relationship between these risks and age at first contact for schizophrenia. Method A nested case-control study design was employed. Psychiatric admission data and socio-economic data were available for 7704 cases admitted between 1981 and 1998 in Denmark, 192 590 gender- and age-matched controls, and for the parents and siblings of all subjects. Results Controlling for socio-economic factors, risk for schizophrenia was associated with a family history of all psychiatric disorders except substance misuse and independently with a family history of suicide. The risk for schizophrenia associated with a family history of psychiatric disorders decreased as age at first contact increased. Conclusions Risk for schizophrenia is associated with a range of psychiatric disorders in family members and these risks are not constant across the risk period., Declaration of interest None.