A new study has revealed key neurobiological differences among young adults with bipolar disorder in the hopes of identifying risk factors for suicidal behavior.
Yale researchers used a breakthrough neuroimaging technique called multimodal MRI scans to collect three types of data on study participants: size and shape of gray matter regions, structural integrity of white matter and interactions between various regions of the brain.
The study, which was published online on Jan. 31 in the American Journal of Psychiatry, split study participants with bipolar disorder into two groups: those who had attempted suicide and those who had not. They also collected data from participants without bipolar disorder as controls.
“On average, we saw some subtle decreases in the gray matter, subtle decreases in structural integrity of the white matter and subtle decreases in functional connectivity [in people who had attempted suicide],” corresponding author and Yale School of Medicine neuroscience professor Hilary Blumberg said. “Specifically, each of these were seen in areas of the brain that are important in emotional regulation.”
In most individuals, the ventral prefrontal cortex regulates emotion by inhibiting the amygdala region of the brain, but the researchers viewed a decrease in the ability to regulate this region in bipolar individuals who had attempted suicide.
While this kind of comparison has been carried out previously on a clinical level, the Yale study simultaneously looked at functional and structural neuroimaging, which had never been done before for youth with bipolar disorder, according to Tina Goldstein, a professor at the University of Pittsburgh Medical Center.
Blumberg said she decided to study suicide in young adults with bipolar disorder in order to try and make the biggest impact on a “serious and devastating” consequence of the illness.
“I have this feeling that I can’t go fast enough to try to do this work, given the high rates of suicide,” she said, adding that 5,000 young adults and adolescents die by suicide every year in the U.S. alone and 50 percent of those with bipolar disorder will attempt suicide at some point in their lives.
Individuals with early-onset bipolar disorder are among the highest-risk population for death by suicide, Goldstein said. She added that even though the illness only affects between 1 and 3 percent of the population, it is important to study this specific sample because they are “ultrahigh-risk” for negative outcomes.
According to Blumberg, the study has received positive attention within the field. In a press release, Douglas Meinecke of the National Institute of Mental Health praised the study for finding functional differences that correlate with suicide risk.
“The findings by Dr. Hilary Blumberg and her research team in adolescents with bipolar disorder who have made suicide attempts is a considerable step forward,” Meinecke said in the release. “If these results are also true for suicide risk in general, then those functional differences represent a clinical marker for risk which is an important advance.”
Goldstein said she was glad to see the study getting attention since looking at suicide risk in young adults with bipolar disorder is, by and large, understudied and underfunded.
The long-term goal of the research, Blumberg said, is to better understand why suicidal thoughts and behaviors develop and who is at highest risk for developing them in order to aid those in particular danger. She added that by showing that underlying neurobiological differences exist, researchers can help destigmatize mental illness.
A limitation of the study was its modest sample size, Blumberg said: Of the group with bipolar individuals, the study had 26 participants who had attempted suicide and 42 who had not.
Goldstein agreed but said that a sample size like this is typical of the field due to the low number of young adults with diagnosed bipolar disorder. She added that another challenge of the research was distinguishing between an individual’s brain activity due to his or her current state and his or her more general course of illness, since bipolar disorder is an episodic illness.
“When the young people were scanned, they were in various mood states at the time, so some of them were depressed, some of them were manic and some of them were stable. So it is hard to tease out the effects of their current mood state,” Goldstein said.
Since the study could also be limited in identifying future risk, the team is now following groups of adolescents over time and tracking suicide attempts to see which kinds of brain differences are associated with suicidal tendencies, Blumberg said.
Suicide is the second-leading cause of death in young people aged 15 to 24 in the United States, according to the NIMH.