This study provides important and partly new information on long-term psychiatric outcomes after preterm birth. It is a historical, population-based cohort study using data from Swedish national registers, showing increased risk for severe psychiatric disorders—nonaffective psychosis, depressive, bipolar, and even eating disorders—in the very preterm population. The risk was also increased, although to a lesser degree, for the moderately preterm group (except for eating disorders). Maternal psychiatric history, socioeconomic or perinatal factors could not explain the findings. Interestingly, being small for gestational age increased the risk for drug and alcohol dependency.

This expands present knowledge, and supplements the emerging evidence of increased risk for adult psychiatric disorders in low-birth-weight populations (Moster et al., 2008; Walshe et al., 2008; Hack, 2009; and Lund et al., 2011). The study takes care of several aspects that usually limit other studies: a large sample size, inclusion of the moderately preterm group, maternal psychiatric morbidity, and a range of prenatal and perinatal factors. As such, this well-performed study deserves credit. The results underline the concern that psychiatric morbidity is one of the major health issues after preterm birth.

The authors suggest impaired neurodevelopment as a plausible biological basis for psychiatric disorders associated with preterm birth. They propose that similar etiologies may lead to a variety of different outcomes, although non-optimal fetal growth may represent other or additional risk factors. Future studies combining advanced cerebral MRI techniques, and clinical, genetic/epigenetic, and environmental data, may provide new knowledge on the etiology. A better understanding of the mechanisms involved may point to improved prevention and intervention aiming to reduce the psychiatric morbidity for low-birth-weight individuals.

References:

Hack M. Adult outcomes of preterm children. J Dev Behav Pediatr 2009;30(5):460-70. Abstract

Lund LK, Vik T, Skranes J, Brubakk AM, Indredavik MS. Psychiatric morbidity in two low birth weight groups assessed by diagnostic interview in young adulthood. Acta Paediatr 2011;100:598-604. Abstract

Moster D, Lie RT, Markestad T. Long-term medical and social consequences of preterm birth. N Engl J Med 2008;359:262-273. Abstract

Walshe M, Rifkin L, Rooney M, Healy E, Nosarti C, Wyatt J, Stahl D, Murray RM, Allin M. Psychiatric disorder in young adults born very preterm: Role of family history. European Psychiatry 2008;23:527-531. Abstract

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