According to the research of Chiara Nosarti, Ph.D., babies born prematurely appear to have an increased risk for developing mental illness, including schizophrenia, depression and bipolar disorder. Dr. Nosarti led a team from King’s College London and Karolinska Institutet, Sweden, in one of the largest investigations to date into the relationship between birth complications and mental health.
Research that has previously suggested a relationship between schizophrenia and pre-term birth left unclear whether such an association existed for other brain and behavior disorders. To explore this, Dr. Nosarti and colleagues compared data from the Swedish Medical Birth Register on more than 1.3 million people born between 1973 and 1985 and the records of adult-onset psychiatric admissions (age 16 and over) from the Swedish National Board of Health and Welfare.
A normal full gestation term is from 37 to 41 weeks. Dr. Nosarti’s examination revealed that babies born at 32 to 36 weeks’ gestation were 1.6 times more likely than full term babies to develop psychosis, 1.3 times more likely to have depressive disorder and 2.7 times more likely to have bipolar disorder. The risk for babies born at less than 32 weeks’ gestation was greater. These babies were 2.5 times more likely to go on to develop psychosis, 2.9 times more likely to have depression and a striking 7.4 times more likely to have bipolar disorder.
Announced online on June 1 in the Archives of General Psychiatry, the study is the first to report an association between pre-term birth and depressive disorder and bipolar affective disorder. The study also found that the association between premature birth and psychiatric outcomes persisted even after adjusting for other factors such as poor fetal growth, a poor Apgar score (a test of infant health administered immediately after the birth process), maternal characteristics or maternal psychiatric history.
Dr. Nosarti, a senior lecturer in mental health studies and neuroimaging at the Institute of Psychiatry, at King’s College London, and her team, conducted other studies using functional MRI in young adults born very pre-term. These showed neuroanatomical alterations in brain networks also found to be disrupted in psychiatric populations.
“Since we considered only the most severe cases that resulted in hospitalization,” Dr. Nosarti says, “it may be that, in real terms, this link is even stronger.” She cautions, however, that it is important to remember that despite the increased risk, these disorders affect only a small percentage of babies born prematurely.
The research has attracted scientific and popular interest. In an article in The New York Times, Dr. Bradley Peterson, Director of the Center for Developmental Neuropsychiatry at the New York State Psychiatric Institute, was quoted as saying that the size of the sample “allows very strong levels of confidence that the findings are not spurious.” Also quoted in the Times, Dr. Catherine Monk, Associate Professor of Clinical Psychology at Columbia University, who conducts research in perinatal psychiatry and neuroscience, called the work “an important, expertly executed epidemiological study” that provides “compelling evidence that our mental health trajectories are initiated early in development.”