IL-6 in Blood and Bone Marrow Linked to Lack of Resilience to Stress
Rodents who are repeatedly defeated by larger animals often exhibit depression-like behaviors. In new research that researcher Georgia E. Hodes presented at the 2016 meeting of the Society of Biological Psychiatry, animals who are susceptible to these social defeat stress behaviors showed immune irregularities, including high levels of the inflammatory marker interleukin-6.
An intervention to prevent the mice from secreting interleukin-6 in blood and bone marrow took away their susceptibility to social defeat stress. When bone marrow from rodents with no interleukin-6 was transplanted into susceptible mice, the recipients showed resilience to social defeat stress. Conversely, a transplant from susceptible mice to those mice without IL-6 led to social defeat stress in the previously “immune” mice.
This research shows that the peripheral immune system, including blood and bone marrow, plays an important role in depression-like behaviors in mice.
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Child Abuse Linked to Adolescent Obesity
New research clarifies how trauma in early life can lead to obesity in adolescence. In a study of 160 young people between the ages of 9 and 15, researcher Janitza Montalvo-Ortiz and colleagues identified seven sites in the genome where DNA methylation predicted body mass index (BMI) in adolescence. The researchers also collected information on family traumas that occurred during the participants’ childhoods and found that DNA methylation and family trauma such as child abuse interacted to predict BMI.
Epigenetics describes the ways life experiences can change how easily DNA is turned on or off. While the genes coded by DNA sequences one inherits from one’s parents never change, the structure of DNA can change. DNA methylation is one type of epigenetic change that refers to the addition of methyl groups to promoter regions of DNA in response to life events.
In this research, which was presented at the 2016 meeting of the Society of Biological Psychiatry, Montalvo-Ortiz and colleagues found that the site of DNA methylation with the strongest link to BMI in adolescence was a gene called MAP2K3. This gene had previously been linked to obesity, but this is the first time DNA methylation at this site has been linked to both obesity and childhood trauma. Other relevant gene sites where DNA methylation occurred include ANKRD2, CPXM2, NUBPL, and RFK.
Certain Types of Inflammation and BMI Predict Depression
At the 2016 meeting of the Society of Biological Psychiatry, researcher Femke Lamers and colleagues presented findings from the Netherlands Study of Depression and Anxiety. The inflammatory markers interleukin-6 and CRP were elevated in people with current major depression. These measures were correlated with BMI, a measure of body weight. High levels of interleukin-6 at the beginning of the study predicted who would have a chronic course of illness.
Editor’s Note: Previous studies have found that elevated levels of CRP predicted a future mood episode in people at high risk for bipolar disorder due to a family history of the illness.
These studies suggest that it might be useful to assess levels of these inflammatory markers (CRP, interleukin-1, interleukin-6, and TNF-alpha) in young people who are at high risk for bipolar disorder. Factors that put someone at high risk include a family history of depression or bipolar disorder, a history of adversity in childhood (abuse, neglect, loss of a parent, etc.), and preliminary symptoms.
Several interventions are available that may reduce the likelihood that someone at risk for bipolar disorder will go on to develop the illness. Family interventions such as the Family Focused Therapy developed by researcher David Miklowitz are helpful. In a 2013 study in the Journal of the American Academy of Child and Adolescent Psychiatry, Miklowitz reported that Family Focused Therapy outperformed treatment as usual for youth at risk for bipolar disorder.
Measures of inflammation might provide additional rationale for beginning interventions in youth at high risk for mood disorders. In addition to family interventions, omega-3 fatty acid supplementation is a low-risk option that is supported by some positive data. Since BMI was implicated in the study by Lamers and colleagues, keeping weight under control might also have some benefit.
For adults with depression who want to keep their weight under control, the combination of the antidepressant bupropion XR (150–300mg/day) and naltrexone (50mg/day), an opiate antagonist medication normally used to fight addictions, has been effective.
Emotional Abuse Increases Inflammation
Trauma in childhood is a risk factor for depression, and both childhood trauma and depression have been linked to increased inflammation. In a study presented at the 2016 meeting of the Society of Biological Psychiatry, Sarah R. Horn and colleagues found that emotional abuse in childhood predicted high levels of inflammation measured in the blood in adulthood.
Horn and colleagues took blood samples from 35 people with treatment-resistant depression and 28 healthy control subjects. The researchers measured inflammatory markers in the blood and also interviewed the participants about any physical, sexual, or emotional abuse they experienced in childhood. Among all the participants, emotional abuse was linked to elevated levels of several inflammatory markers, including interleukin-6, interleukin-10, interleukin-1a, interleukin-15, and fractalkine.
The researchers suggest that more research is needed to clarify the link between early trauma, depression, and inflammation. How elevated inflammation in people with a history of abuse may influence the effectiveness of different psychotherapies and medications for depression remains to be determined.
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.
Intranasal Oxytocin Soon After a Trauma May Prevent Worsening PTSD
Oxytocin, a hormone that promotes emotional bonding, also benefits people having trouble dealing with stress. A new study suggests that giving oxytocin for a week shortly following a traumatic experience reduces the risk that the recipient will develop post-traumatic stress disorder (PTSD).
In the study by researcher Mirjam van Zuiden and colleagues, people who visited an emergency room following some kind of trauma were randomized to receive either a placebo nasal spray or intranasal oxytocin twice daily for 7.5 days beginning within 12 days after the trauma. The dosage was 40 IU twice daily.
For those participants with severe PTSD symptoms at baseline, repeated oxytocin administration prevented worsening PTSD. The research was presented at the 2016 meeting of the Society of Biological Psychiatry.
