Perinatal and familial risk factors of youth suicidal behaviour

Sammanfattning: Completed suicide constitutes one of the leading causes of death in adolescents and young adults. Youth suicide attempt often precedes completed suicide and represents in itself a considerable public health problem in Sweden and in other European countries. The aims of this study were to 1) scrutinise trends in suicide mortality in adolescents compared to trends in an older age group and in relation to changes in reporting practices in European countries, 2) investigate the relation of maternal, pre- and perinatal factors with subsequent suicidal behaviour in young adults, 3) analyse the association of foetal and childhood growth and their interaction with subsequent suicide attempt by violent and nonviolent means, and finally 4) analyse the independent and interacting effects of familial and individual psychopathology as well as familial suicidal behaviour on suicide attempt in young adults. For this purpose, the WHO mortality database has been used for the analysis of European suicide trends from 1979 to 1996 in Study I. For the investigation of pre-and perinatal, childhood and familial factors in relation to subsequent suicidal behaviour up to seven Swedish registers were linked: the Medical Birth register, the 1990 Population and Housing Census, the Inpatient Care Register, the Cause of Death Register, the Multi Generation Register, the Military Service Conscription Register and the Register of the Total Population. The birth cohort 1973-80 was followed up to 1999 using a cohort study design in Study II and III, including 713,370 individuals in Study II and 318,953 males in Study III. In paper IV all individuals, who were born 1968-80 and who had attempted suicide (14,440 cases) until 1999 were matched for gender, county and month of birth with 144,400 controls. Suicide rates in adolescents increased for males in twenty-one and for females in eighteen of the thirty European countries during the 1980s and mid-1990s. These increases were generally accompanied by stable or decreasing trends in suicide rates of males and females of 20 years and over. In several countries changes in reporting practices affected to different degrees the temporal variations in adolescent suicide rates, primarily in males. Results from Study II revealed that teenage motherhood increased the risk of both suicide attempt and completion in adolescents and young adults. Multiparity and low maternal education predicted suicide attempt in young offspring. Preterm birth was a strong predictor for violent suicide attempt. Restricted foetal growth was associated with both suicide completion and attempt. The inverse association of foetal growth and suicide attempt did not seem to be modified by childhood growth (Study III). Decline in postnatal linear growth potential entailed an additional risk. Familial suicidal behaviour, primarily suicide attempt, and familial psychopathology, mainly substance abuse and personality disorders, were significantly associated with an increased risk of suicide attempt in young adults. There seemed to be an effect of familial suicidal behaviour as well as familial psychopathology on youth suicide attempt beyond the transmission of mental illness. Familial suicidal behaviour had a stronger effect on suicide attempt of early onset and on boys. Individual psychopathology, primarily substance abuse, affective and personality disorders, emerged as the strongest risk factor for suicide attempt in young adults. Significant interactions were also observed between psychopathology in index subjects and familial suicidal behaviour.