Depression during pregnancy linked to epigenetic changes in the placenta

Depression during pregnancy has been linked to placental gene modifications according to a study conducted by NIH researchers.

Researchers at the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development carried out a genetic analysis on placenta samples delivered from 301 pregnant women who had taken part in a previous study on fetal growth, which recruited low-risk pregnant women. They discovered 16 epigenetic changes that were linked to depression and two that were linked to stress.

Published their findings in Epigenomics, the researchers stated that: 'Some of the epigenetic changes in the placenta linked to depression were located close to genes which are known to have important roles in brain development and occurrence of psychiatric disorders.'

Dr Fasil Tekola-Ayele, lead investigator, and colleagues asked the women taking part in the study to complete questionnaires on their levels of stress and depression throughout their pregnancies. An epigenome-wide association study was then conducted on the placenta samples to determine whether there are any changes that occur to the placental epigenome that can be associated to depression or stress.

The modifications that the researchers discovered to the epigenome involved DNA methylation, which is the binding of compounds known as methyl groups to DNA. These changes are able to modify a gene's activity. They found 16 changes associated with antenatal depression in the second and third trimesters and two changes associated with perceived stress in the third trimester of pregnancy.

Several of these changes were found in genes that are implicated in neurological pathways. NF-α1 is essential for the neuroprotective effects of key molecules that prevent neurodegeneration. ADAM23 is known to regulate neurodevelopment. HCG9, VSTM2L and SMOC1 are implicated in neuropsychiatric disorders.

Previous studies have shown that stress or depression during pregnancy is associated with chemical modifications to placental genes. Further, associations between depression in pregnancy have been linked to a higher risk for depression in children.

The researchers suggest in their paper: 'that maternal depression in pregnancy could have long-term implications for the mental development of the child... and call for long-term studies to determine whether epigenetic changes in the placenta associated with stress and depression can be used to predict children's mental health outcomes.'

The epigenetic changes discovered in the placentas exposed to antenatal depression in this study are relevant to biological processes involved in neurodevelopment and neuropsychiatric disorders. Furthermore, the changes suggest possible fetal brain programming.