The King’s College London has reported that one of the largest studies to investigate birth complications and later mental health has found that premature birth constitutes a single, independent risk factor for a range of severe psychiatric disorders. Researchers at the Institute of Psychiatry (IoP) at King’s College London and Karolinska Institutet in Sweden suggest that neuro-developmental differences in those born prematurely may be important in understanding the link.
This study, which has been published in The Archives of General Psychiatry, found that persons born very prematurely, which is defined as less than 32 weeks gestation, were three times more likely to be hospitalized with a psychiatric disorder at age 16 years and older, compared to those born at term, which is defined as 37 to 41 weeks gestation. The risk varied depending on the condition -- for psychosis it was 2.5 more likely, for depression three times more likely, and for bipolar disorder 7.4 times more likely. The findings also revealed a smaller increased risk for those born moderately prematurely, which is defined as 32 to 36 weeks.
Previous research has shown an association between premature birth and an increased risk of schizophrenia, but this report claims that this is the first study to demonstrate an association with a broad range of psychiatric disorders, including bipolar disorder, psychosis, and depression.
Dr. Chiara Nosarti, lead author of the paper at the IoP at King’s, says, “We found a very strong link between premature birth and a range of psychiatric disorders. Since we considered only the most severe cases that resulted in hospitalization, it may be that in real terms this link is even stronger. However, it is important to remember that even with the increased risk, these disorders still only affect 1% to 6% of the population.”
The researchers analyzed data from nearly 1.5 million Swedish birth and medical records between 1973 and 1985 and identified all those admitted to hospital with their first episode of a psychiatric disorder by 2002.
Dr. Nosarti says, “We believe that the increased risk of mental disorders in those born very prematurely can be explained by subtle alterations of brain development. The immature nervous system in those born prematurely is particularly vulnerable to neonatal brain injury resulting from birth complications.”
Dr. Nosarti continues, “The strongest association we found in this study was to mental health disorders known to have a strong biological basis, such as bipolar disorder, further adding to the theory that neuro-developmental differences in those born prematurely may play an important role for later mental health.’”
The authors point to the importance of raising awareness of the increased risk of mental health disorders in people born prematurely and suggest gestational age should be considered when investigating psychiatric disorders in young adults.
Dr. Nosarti concludes, “Future investigations of the mechanisms associated with the increased risk of mental health following preterm birth may aid the early identification of high-risk children, who could then be prospectively identified and closely monitored – to decide if, when, and what interventions may be appropriate.”
This study was funded by a National Alliance for Research on Schizophrenia and Depression (NARSAD) Brain and Behavior Research Foundation and supported by the National Institute of Health Research (NIHR) Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and the Institute of Psychiatry, King’s College London.