Infliximab Helps the Subgroup of Bipolar Depressed Patients Who Faced Adversity in Childhood
At the 2019 meeting of the International Society for Bipolar Disorders, researcher Mike Cosgrove and colleagues described a study of the immune-suppressing drug infliximab in adults with bipolar disorder. The researchers found persistent significant improvements on infliximab only in those with bipolar disorder who also had a history of childhood adversity. Childhood adversity is consistently associated with elevated levels of inflammatory cytokines, and baseline inflammation may be a prerequisite for a positive effect from infliximab, which works by blocking the inflammatory cytokine TNF alpha.
Inflammatory Marker IL-6 is Elevated in People with Depression and Those with a History of Childhood Trauma
In a 2018 article in the journal Psychiatry Research, researcher Ana Munjiza and colleagues reported that the inflammatory marker IL-6 was higher in 64 depressed people than in 53 non-depressed people, and that levels of IL-6 among people in the depressed group were significantly correlated with scores on a questionnaire in which participants reported traumas experienced in childhood. They reported more physical abuse, physical neglect, and emotional abuse.
Munjiza and colleagues indicate that trauma in childhood is a risk factor for depression in adulthood, as other researchers have suggested, and that inflammation could mediate the relationship between childhood adversity and depression.
Editor’s Note: IL-6 has been associated with antidepressant treatment resistance. IL-6 is secreted from white cells in the blood and from monocytes from the bone marrow in response to stress. It enters the brain and starts an inflammatory cascade that induces depressive behaviors. Animal studies have shown that if IL-6 secretion is blocked, depressive-like behaviors do not occur.
Another indicator of inflammation is CRP, and elevations in CRP have been associated with poor response to selective serotonin reuptake inhibitor (SSRI) antidepressants, and better response to the noradrenergic tricyclic antidepressant nortriptyline and the dopamine active antidepressant bupropion.
Treatments for depressed people with histories of childhood trauma may include psychotherapy, somatic therapies such as repeated transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), and medication. More research is needed to determine the optimal treatment regimens for this subgroup of depression sufferers, including whether anti-inflammatory drugs could play a helpful role in preventing or treating depression. People with elevated inflammatory markers (such as IL-6, CRP, IL-1, or TNF-alpha) are likely to be better candidates for adjunctive anti-inflammatory treatments than those with normal or low baseline levels of inflammation.
Brain Volumes Affected by Type and Timing of Childhood Abuse
Maltreatment during childhood has been linked to brain changes and mental illness. In a study by researcher Carl M. Anderson and colleagues that was presented at the 2016 meeting of the Society of Biological Psychiatry, maltreatment at particular ages was statistically linked to deficits in the size of certain brain areas in young adulthood.
The brain areas under examination are critical for the regulation of emotion and behavior, and this research suggests that early experiences can stunt their development, perhaps through altered production of synapses or via the synaptic pruning process that occurs during preadolescence. The details, summarized below, are perhaps less important than the overall finding that maltreatment in childhood affects brain volume, and this effect varies based on the timing and type of maltreatment. Abuse and neglect earlier in life affected the left side of the brain, while later maltreatment affected the right side.
Severity of physical abuse at age 3 affected the volume of the ventromedial prefrontal cortex in women. Physical abuse at ages 3 and 8 in men affected left ventromedial prefrontal cortical volume, while later abuse at ages 7 and 12 predicted volume of the right side.
In women, dorsal anterior cingulate area on the left was predicted by physical abuse at age 5 and by emotional neglect at ages 7 and 11. Later emotional neglect at ages 15 and 16 and physical abuse by a peer at age 10 was associated with smaller right dorsal anterior cingulate. In men, smaller left dorsal anterior cingulate area was predicted by physical neglect at age 2 and emotional abuse by a peer and witnessing abuse of a sibling at ages 5 and 10, and right area by physical neglect at age 12.
Mothers Who Were Abused in Childhood Secrete Less Oxytocin While Breastfeeding
A recent study suggests that women who experienced moderate or severe abuse in childhood secrete less oxytocin while breastfeeding their own children. Oxytocin is a hormone that promotes emotional bonding. The study included 53 women. They breastfed their newborn children while blood samples were collected from the women via IV. Those women with a history of moderate or severe abuse (emotional, physical, or sexual) or neglect (emotional or physical) had lower measures of oxytocin in their blood during breastfeeding than women with no history or abuse in childhood or a history of mild abuse.
A history of abuse or neglect was more common among women with current depression compared to women with a history of depression or anxiety. Women who had never experienced depression or anxiety were least likely to have a history of abuse or neglect.
The study by Alison Steube and colleagues, presented at the 2016 meeting of the Society of Biological Psychiatry, suggests that traumatic events that occur during childhood may have long-lasting effects. These experiences may modulate the secretion of oxytocin in adulthood. Low oxytocin has been linked to depression.
Adversity May Increase Risk of Mood Disorders
In adults with bipolar disorder, adversity in childhood has been associated with an earlier onset of bipolar disorder compared to those who did not experience some form of adversity such as verbal abuse, physical abuse, sexual abuse, loss of a parent, abandonment, or neglect. At the 2013 meeting of the Society of Biological Psychiatry, Nancy Low et al. reported that the number of these stressful life events a child experienced was associated with the number of their anxiety symptoms, psychiatric disorders, and lifetime substance abuse. Having experienced 3 or more adversities was associated with a 3.5-fold increased risk for developing a mood disorder and a 3-fold increase in anxiety disorders and alcohol or drug abuse.
While the study has not yet been published in a peer-reviewed journal, the abstract (#194) may be found in the meeting supplement, Volume 73, Number 9S of the journal Biological Psychiatry.
Editor’s Note: Low’s study is the first to report that childhood adversity is a risk factor for the onset of bipolar disorder in the general population.
Given the increasing evidence for the persistence of epigenetic marks on DNA and histones (which can’t change the sequence of genes but can change their structure) in those who have experienced such stressors in childhood, this could provide a mechanism for the long-term vulnerability of these children to the development of mood disorders and a variety of physical illnesses.
