Both childhood adversity and recent stressors predict risk of developing bipolar disorder as well as the recurrence of bipolar episodes, a large study published April 22 in Molecular Psychiatry has found.
The research team was headed by Stephen Gilman, Sc.D., of the Harvard School of Public Health, and Roy Perlis, M.D., an associate professor of psychiatry at Harvard Medical School and medical director of the Bipolar Clinic and Research Program at Massachusetts General Hospital.
The study was based on a nationally representative sample of 33,375 Americans of whom 1,219 already had been diagnosed with bipolar disorder at the start of the study. All of the subjects were evaluated for childhood adversities and stresses during the previous year and followed up for a three-year period to see whether they experienced any bipolar episodes. During the follow-up period, 631 subjects had their first onset of bipolar disorder, while 180 of the 1,219 subjects who already had bipolar disorder experienced recurrent episodes.
The researchers then assessed whether there was a link between experiencing childhood adversities and the onset of bipolar disorder during the follow-up period. The study found that individuals who had incurred physical abuse, sexual abuse, or economic deprivation during childhood were two to three times more likely to develop bipolar disorder during the follow-up period than were individuals who had not encountered such negative experiences.
After that, the researchers focused on the subjects who already had bipolar disorder at the start of the study to see whether experiencing childhood adversities predicted recurrent bipolar episodes during the follow-up period. They found that study subjects who had been physically or sexually abused in childhood were twice as likely to have recurrent bipolar episodes as subjects who had not been abused.
The researchers then determined whether subjects who had bipolar disorder at the start of the study and who had encountered stresses during the previous year experienced significantly more recurrent bipolar episodes than bipolar subjects who had not encountered such stresses. Their data showed that subjects who had experienced personal losses, interpersonal problems, or financial difficulties during the previous year were two to three times more likely to have recurrent bipolar episodes during the follow-up period.
Finally, they assessed whether past-year stresses significantly predicted a first onset of bipolar disorder among subjects who had not been previously diagnosed with the illness. When compared with subjects who had experienced few stresses, those who had were two to three times more likely to develop the illness.
Thus, both negative childhood events and recent negative life events seem to contribute to bipolar illness, Gilman, Perlis, and colleagues concluded, and “add to our understanding of the nongenetic component of the etiology of bipolar disorder, which according to family studies accounts for approximately 20 percent of population variance.”
The findings also have clinical implications, Perlis said in an interview with Psychiatric News. It is important “to redouble our efforts to do psychotherapy with people with bipolar disorder” in order to help them deal with adverse life experiences that may be contributing to their illness.
The research was funded by the National Institutes of Health. ■