Suicidal behavior in schizophrenia and family history of suicide

Abstract

Suicide is a complex behavior with dramatic personal, familial, and economic consequences. “Suicidal behavior” refers to three different behaviors: completed suicide, suicide attempts (SA), and suicidal ideation. Completed suicide and SA, but not ideation, are behaviors on the same continuum and expressions of the same liability, according to family and biological studies.1,2 Suicide is the leading cause of premature death in schizophrenia, and 2% to 12% of people who commit suicide suffer from schizophrenia. Harris and Barraclough3 estimated that the standardized mortality ratio (100 x sum of observed deaths /sum of expected deaths) in schizophrenia is 845. Various studies have reported a lifetime suicide rate of 10% to 13% in people suffering from schizophrenia. Recently, Inskip et al4 reanalyzed most of the previous studies using generalized linear modeling. They concluded that this rate is closer to 4% (in this meta-analysis the lifetime suicide rate was 6% for affective disorder and 7% for alcohol dependence). SAs occur quite often in schizophrenia: their frequency ranges from 20% to 55%. More than 50% of schizophrenic suicide attempters report more than one SA. SA is considered to be one of the most powerful predictors of future SA and completed suicide. Genetic factors contribute to the liability to suicidal behavior, and heritability of suicidal behavior is estimated to be 45%. 5 A family history of suicide increases the risk for suicide and SA.6 The impact of a family history of suicide has been studied mainly in depression, and much less frequently in patients with schizophrenia.6,7 It remains to be determined whether a family history influences SA characteristics in schizophrenia. The goals of the present study were twofold: To determine and compare the frequency of a family history of suicide in patients with schizophrenia and in normal controls. To determine the influence of a family history of suicide on the frequency of SA in patients with schizophrenia and on SA characteristics.