The association of family size and birth order in adolescence to the likelihood of developing psychotic disorders in young adulthood: A follow-up study of former adolescent inpatients

• Published in: Psychiatry research 2024-03, Vol.333, p.115719-115719, Article 115719
• Main Authors: Eskelinen, Siiri, Halt, Anu-Helmi, Hakko, Helinä, Riipinen, Pirkko, Riala, Kaisa
• Format: Article
• Language: English
• Subjects: Adverse childhood experience; Father; Grand multiparity; Large family; Male sex; Schizophrenia spectrum disorder
• ISSN: 0165-1781; 1872-7123
• DOI: 10.1016/j.psychres.2024.115719

•Large family size in adolescence associate with an increased likelihood of developing schizophrenia spectrum disorder (SSD) and a psychotic disorder other than SSD by young adulthood.•Father's psychiatric problems, as perceived by the adolescent, and having a father who is unemployed associate with an increased likelihood of developing SSD.•First-born or only-child participants were less likely to have a psychotic disorder other than SSD than those with middle-born sibling position.•When diagnosing and treating adolescents with psychotic symptoms, information regarding their family size and sibling position may be relevant. This is a clinical follow-up study of 508 former adolescent psychiatric inpatients admitted to hospital between 2001 and 2006 in Northern Finland. The participants were interviewed using the K-SADS-PL and the EuropASI instruments. Until 2016, the national Finnish Care Register for Health Care provided data on psychiatric diagnoses. Using logistic regression analysis, we examined how birth order and childhood family size affected the incidence of schizophrenia spectrum disorder (SSD) and other psychotic disorders by young adulthood. Participants were separated into three diagnostic subgroups 1) participants with SSD (n = 76), 2) participants with a psychotic disorder other than SSD (n = 107) and 3) participants with only one nonpsychotic depressive episode (n = 118). The main conclusions were that large family size in adolescence (six or more children), male sex and father having psychiatric problems or being unemployed, were significantly associated with a higher likelihood of SSD among study participants. Large family size also associated to a higher likelihood of developing other psychotic disorders. Being the first born or an only child reduced the likelihood of psychotic disorders other than SSD. When diagnosing and treating children and teenagers with psychotic symptoms, information regarding their family size and sibling position may be relevant.