Sibship size, birth order, family structure and childhood mental disorders.

PURPOSE

The aim of this study was to determine the role that birth order, sibship size and family structure have as risk factors in the development of common childhood mental disorders.

METHOD

A case-control study design was conducted (N = 16,823). The group under study consisted of all those subjects who had consulted with a psychiatrist/psychologist and had received a clinical diagnosis at public mental health centres within the Region of Madrid (Spain), between 1980 and 2008. A multiple logistic regression was used to explore the independent association with each diagnosis: emotional disorders (ED) with onset specific to childhood, attention deficit hyperactivity disorder (ADHD), conduct disorder (CD), mental retardation (MR), and pervasive developmental disorder (PDD).

RESULTS

Birth order and family structure significantly predicted the risk of being diagnosed with ED or ADHD. In addition, sibship size and sex predicted the risk of being diagnosed with a childhood mental disorder.

CONCLUSIONS

We concluded that being the middle child and living with both biological parents appear to be protective factors against the development of ED or ADHD. Living in large families appears to increase the risk of receiving a CD, MR, or PDD diagnosis. Further research is warranted.