A new study, published in the journal Brain, Behavior and Immunity, has revealed that a runaway, inflammatory immune response may be responsible for triggering severe depression during and after pregnancy.
This depression is not the same as “baby blues”, which is common right after delivery. Pregnancy-related depression is in fact a serious medical condition which can even require hospitalisation due to escalating severity. One in five new mothers experience depression after pregnancy, with their symptoms generally beginning during pregnancy and worsening after delivery. It has been estimated that 14% have suicidal ideation during pregnancy.
“Pregnancy-related depression is common yet poorly understood,” said Lena Brundin, M.D., Ph.D., an associate professor at Van Andel Institute and senior author of the study. “Biologically speaking, pregnancy is a major inflammatory event that can upend many of the body’s day-to-day molecular processes. If we can better understand these irregularities, it could lead to new ideas about how best to treat perinatal depression.”
The researchers analysed blood samples from 165 participants at Pine Rest’s Mother and Baby Program and the Obstetrics and Gynecology Clinic at Spectrum Health in Grand Rapids.
The results showed that multiple inflammatory factors appear to contribute to pregnancy-related depression. Levels of IL-6 and IL-8 – inflammatory chemicals called cytokines – were elevated. Levels of another cytokine, IL-2, were low – this cytokine plays a significant role in immune function. At the same time, there was a drastic reduction in serotonin, which regulates mood.
The team believe that these changes are due to alterations in the way tryptophan, a molecular building block required for serotonin production, is hijacked and shunted away by the kynurenine pathway, a molecular cascade closely linked to inflammation. The loss of serotonin this results in tracks with the intensity of the depression – the less serotonin present, the more severe the symptoms.
“Inflammation is an important and normal part of the immune system and, in early pregnancy, prevents the mother’s immune system from attacking the fetus. However, when the inflammatory reaction is protracted or more intense than is optimal, it may lead to worsening depression in a subset of vulnerable women,” said Eric Achtyes, M.D., M.S., staff psychiatrist at Pine Rest, an associate professor at Michigan State and the study’s lead author. “Hopefully, this study will allow us to develop treatments that more specifically target those who are at risk for an ‘inflammatory’ perinatal depression.”depression, mental health, pregnancy