An uncontrolled inflammatory immune response may be responsible for triggering severe depression during and after pregnancy, according to a new study published in the journal Brain, Behavior and Immunity.
It should not be confused with the so-called ‘baby blues, which is the depression that appears immediately after childbirth. Pregnancy-related depression is a serious medical condition that can increase in severity and may even require hospitalization. One in five new mothers experience depression after pregnancy, with symptoms that begin during gestation and usually worsen after delivery. It is estimated that 14% have suicidal thoughts during pregnancy.
Pregnancy-related depression is common but little known, says Lena Brundin, associate professor at the Van Andel Institute and lead author of the study. Biologically speaking, pregnancy is an important inflammatory event that can alter many of the body’s day-to-day molecular processes. If we can better understand these irregularities, it could generate new ideas about the best way to treat perinatal depression.
The team, which included researchers from Pine Rest Christian Mental Health Services and Michigan State University, analyzed blood samples from 165 patient volunteers in the Pine Rest Mother-Baby Program and the Obstetrics and Gynecology Clinic at Spectrum Health in Grand Rapids, all in the United States.
They found that several inflammatory factors appear to contribute to the onset and severity of pregnancy-related depression. Levels of IL-6 and IL-8, both inflammatory chemicals called cytokines, rose, while levels of another cytokine called IL-2, which plays an important role in immune function, were low. At the same time, there was a drastic reduction in serotonin, an important chemical mood regulator.
These changes point to alterations in the way a molecular building block called tryptophan, which is required for serotonin production, is sequestered and derived via kinurenin, a molecular cascade closely related to inflammation. The resulting loss of serotonin tracks with intensity of depressive symptoms; the less serotonin, the more severe the symptoms.
Inflammation is an important and normal part of the immune system and, at the beginning of pregnancy, prevents the mother’s immune system from attacking the fetus. However, when the inflammatory reaction is prolonged or more than optimal, it can worsen depression in a subset of vulnerable women, adds Eric Achtyes, a psychiatrist on the staff at Pine Rest, an associate professor in the state of Michigan and lead author of the study. Hopefully, this study will allow us to develop treatments that more specifically target those at risk for ‘inflammatory’ perinatal depression.