Background: There is growing interest in the role of childhood adversities, including parental death and separation, in the etiology of psychotic disorders. However, few studies have used prospectively collected data to specifically investigate parental separation across development, or assessed the importance of duration of separation, and family characteristics.
Method: We measured three types of separation not due to death: maternal, paternal, and from both parents, across the ages of 1-15 years among a cohort of 985 058 individuals born in Denmark 1971-1991 and followed to 2011. Associations with narrowly and broadly defined schizophrenia and bipolar disorder in the psychiatric register were assessed in terms of separation occurrence, age of separation, and number of years separated. Interactions with parental history of mental disorder were assessed.
Results: Each type of separation was associated with all three outcomes, adjusting for age, sex, birth period, calendar year, family history of mental disorder, urbanicity at birth and parental age. Number of years of paternal separation was positively associated with both schizophrenia and bipolar disorder. Associations between separation from both parents and schizophrenia were stronger when separation occurred at later ages, while those with bipolar disorder remained stable across development. The first occurrence of paternal separation appeared to increase risk more when it occurred earlier in childhood. Associations differed according to parental history of mental disorder, although in no situation was separation protective.
Conclusions: Effects of parental separation may differ by type, developmental timing and family characteristics. These findings highlight the importance of considering such factors in studies of childhood adversity.
Keywords: Bipolar disorder; parental separation; psychosis; schizophrenia.