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.
A history of childhood maltreatment increases the risk that a person will attempt suicide. Different types of maltreatment, such as physical abuse, emotional abuse, sexual abuse, and neglect, often overlap. In a 2015 study in the Journal of Clinical Psychiatry, researcher Nicolas Hoertel and colleagues used data from an epidemiological survey of 34,653 Americans to clarify the mechanism by which maltreatment is linked to suicide risk.
Hoertel and colleagues found that childhood maltreatment in general was associated with an increased risk of attempting suicide and an earlier age at first suicide attempt. The analysis controlled for demographic characteristics and psychiatric diagnoses. Most of the risk came from effects that were shared across all the types of maltreatment. However, sexual abuse directly conferred an additional risk of suicide attempt.
In an earlier study of 648 outpatients with bipolar disorder by this editor Robert Post and colleagues (led by Gabriele Leverich), 34% had a history of suicide attempts, and these participants had a higher incidence of traumatic stressors in childhood and more stresses at illness onset than those without a history of suicide attempts. A history of sexual abuse in childhood was also linked to an increased risk of a serious suicide attempt in the earlier study, which appeared in the Journal of Clinical Psychiatry in 2003.
A collaboration between Norwegian and French researchers led by Bruno Etain has clarified the pathway by which childhood trauma is linked to worse outcomes among people with bipolar disorder. The researchers, who presented their work in a poster at the 2015 meeting of the Society of Biological Psychiatry, replicated earlier findings by this editor (Robert Post) that patients who experienced trauma as a child had a more adverse course of bipolar disorder. Etain and colleagues found a link between childhood trauma and an earlier age of onset of bipolar disorder, rapid cycling, suicide attempts, and cannabis misuse.
The researchers identified more than 550 patients with bipolar disorder, who answered questionnaires about their history of bipolar disorder and childhood trauma. Their DNA was also analyzed, and the researchers found that the effect of childhood trauma on age of onset was mediated by the presence of common genetic variants in proteins related to stress (the serotonin transporter) and immune function (Toll-like receptors). They also found that the traits of mood lability (or moodiness) and impulsivity mediated the effects of trauma on clinical outcomes.
The lasting epigenetic effects of child maltreatment and adversity noted in the above abstract are consistent with a large literature showing more epigenetic effects in these individuals than in controls. While genetics are important, the impact of the environment is also substantial.