Vol 3 n° 2 - Schizophrenia: Specific Topics
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Posters & images in neuroscience Suicidal behavior in schizophrenia and family history of suicide Suicide is a complex behavior with dramatic personal, familial, and economic consequences. “Suicidal behav- ior” refers to three different behaviors: completed sui- cide,  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 Barra- clough3 estimated that the standardized mortality ratio ([100  ´  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 peo- ple suffering from schizophrenia. Recently, Inskip et al4 reanalyzed most of the previous studies using gen- eralized linear modeling. They concluded that this rate is closer to 4% (in this meta-analysis the lifetime sui- cide 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 schizo- phrenic suicide attempters report more than one SA. SA is considered to be one of the most powerful pre- dictors of future SA and completed suicide. Genetic factors contribute to the liability to suicidal behavior, and heritability of suicidal behavior is esti- mated to be 45%.5 A family history of suicide increases the risk for suicide and SA.6 The impact of a family his- tory of suicide has been studied mainly in depression, and much less frequently in patients with schizophre- nia.6,7 It remains to be determined whether a family his- tory 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 sui- cide on the frequency of SA in patients with schizo- phrenia and on SA characteristics. Methods Subjects were over 18 years old and gave informed consent; all subjects had information on both parents. A total of 160 schizophrenic inpatients and 102 nor- mal controls participated in the study. Information on history of personal and familial suicidal behaviors was obtained with the use of a structured interview. Sui- cide methods were classified as low and high lethality as defined in a previous study.8  Subjects were classi- fied in the high-lethality group if they had made at least one high-lethality SA in their life. Normal con- trols were healthy volunteers recruited for phase I drug studies. Results The results of this study are summarized in Tables I to IV.

Table I. Demographics of the study population.

 Schizophrenic Normal patients controls Age (years) 34.2 (SD=13.2) 27.5 (SD=8.8) Sex ratio (male/female) 2.6 (116/44) 11.7 (94/8) Number of brothers 1.4 (SD=1.5) 1.2 (SD=1.3) Number of sisters 1.4 (SD=1.4) 1.2 (SD=1.1) Suicide attempters 50% (80/160) Table II. Characteristics of suicide attempters (for the 80 schizophrenics who had a history of suicide attempts [SA]). Number of SAs 2.9 (SD=3.9) Multiple SAs 44% (35 patients) History of high-lethality SAs 51.2%    (41 patients) Age at first SA (years) 24.3 (SD=8.8) Psychiatric care before first SA 45% (36 patients) SA preceding current hospitalization 13.7%    (11 patients) 1 2 0