Introduction: Familial clustering of suicidal behaviour and psychopathology has been reported in young suicide attempters. Most of these studies were predominantly carried out in clinical treatment settings and lacked statistical power to assess the independent and modifying influences of own and familial psychopathology and suicidal behaviour.
Methods: We carried out a population-based record-linkage study with a nested case control design. The 14,440 individuals hospitalised due to suicide attempt (cases) and 144,400 matched controls were born in Sweden between 1968 and 1980 and followed up till December 31, 1999.
Results: Among the strongest independent familial risk factors for youth suicide attempt were siblings' (OR 3.4; 2.8-4.1), maternal (OR 2.7; 2.5-3.1) and paternal (OR 1.9; 1.7-2.1) suicide attempt. Other important risk factors were familial personality and substance abuse disorders, maternal schizophrenia, non-affective psychoses and organic disorders and parental neurotic, stress-related and somatoform disorders (1.9-3.2 fold increase), and paternal (OR 1.9; 1.6-2.3) and maternal (OR 1.8; 1.3-2.4) suicide completion. Mental illnesses in index subjects, particularly substance abuse, affective and personality disorders, were the dominant determinants of suicide attempt. Strong interactions were observed between psychopathology in index subjects and familial suicidality. Familial suicide completion had a stronger effect on suicide attempt of earlier onset and on boys. Nearly half (47%) of all suicide attempts could be attributed to familial psychopathology (13%), family suicide attempt (7%) and suicide completion (1%) and own psychopathology (25%).
Conclusion: Early recognition and adequate treatment of individual mental illness contribute to prevent youth suicide attempts. Children of parents with psychopathology and suicidal behaviour should receive early support and attention. Evaluation of familial suicidal behaviour seems to be vital for suicide risk assessment in young psychiatric inpatients. There appears to be an independent effect of familial suicidal behaviour as well as familial psychopathology on youth suicide attempt beyond the transmission of mental illness.