People with cancer, heart disease and other conditions have come to expect treatments that their medical teams "personalize" just for them, based on tests.
But care for mental health conditions hasn't gotten to that point yet.
Now, a new study suggests that it might be possible to personalize care for people with bipolar disorder, using the results of detailed personality tests.
The research finds that such tests might help identify people who have certain combinations of personality traits that could raise or lower their risk of repeated depressive episodes or poor functioning in everyday life.
Using data from more than 2,500 people with bipolar disorder who took part in two long-term studies, the researchers say certain personality styles – combinations of personality traits – emerged as predictors of bipolar disorder outcomes. These personality styles are based on within person characteristics rather than these characteristics between individuals. Thus, they are very personalized.
The ratio of protective personality styles to risk-elevating personality styles was especially important.
The study, by researchers from the University of Michigan's Heinz C. Prechter Bipolar Research Program , is published in the Journal of Affective Disorders .
Lead author Kelly Ryan, Ph.D., a neuropsychologist and professor in the U-M Department of Psychiatry , notes that the personality tests used in the study are often used in psychology settings.
"These findings are really exciting because we don't know why some patients with bipolar disorder are more resilient and bounce back or have fewer episodes of depression, but now we can see that this could be linked to the makeup of their personality," she said. "We hope that this can eventually inform the treatment planning that clinicians do for patients, knowing who may be at higher risk."
Patients, too, could act on the result of their personality tests, using them to help understand their experience and working with their clinicians to modify traits that might raise their long-term risk of depression and poor life management.
Personality traits were once thought of as enduring characteristics for each individual, but now there's evidence that traits can change over the course of therapy or with coaching.
For example, someone who scores low on the "openness" personality trait – which, when in the normal or average range, is protective -- might be guided therapeutically to seek out new experiences through arts or nature.
More about the study
Ryan and her colleagues used data from the Prechter program's long-term study that's been gathering data on hundreds of people with bipolar disorder over more than a decade.
The new study is based on a sample of 489 people with bipolar disorder who took the Revised NEO Personality Inventory (NEO PI-R), a 240-item personality test, as well as taking short questionnaires in follow up clinical assessments about their level of depression and life functioning every two months and/or every two years
The researchers assigned each person to their individual personality styles based on scores for various combinations of traits using their test results, a standard practice using the NEO-PI-R, and then looked at each person's number of major depressive episodes and life functioning scores over time. Some of the 30 personality styles emerged as having higher risk for depression and poor functioning, while other personality styles emerged as lower risk.
Not surprisingly, all the personality styles that included a high score on the personality trait called neuroticism (prone to emotional instability and negative thinking) appeared to raise the risk of depression. And styles that involved a low score on neuroticism appeared to be protective against depression.
But other personality styles not involving neuroticism also were associated with higher or lower risk of frequent depression episodes too. The same held true for predicting poor life functioning, with low levels of neuroticism appearing to be especially protective.
Then, they tested this framework on data from another group of over 2,000 people with bipolar disorder, who had enrolled in the STEP-BD trial and taken the shorter NEO Five-Factor Inventory (NEO-FFI) personality test. The STEP-BD group had their depression and life functioning measured by clinicians every three months.
Two-thirds of the 12 personality risk styles that had predicted higher risk of depression in the Prechter group also predicted it in this larger group, while 9 of the 16 styles that had seemed protective in the Prechter group also seemed to have that protective effect in this group. This replication helps Ryan and her colleagues have confidence in the model they created using Prechter data.
Ryan notes that it's the interaction between personality styles, and the balance of protective vs. risk-increasing ones, that appears to matter most and can potentially be used clinically to help those with bipolar have less depressive episodes and higher life functioning.
The study was funded by the Heinz C. Prechter Bipolar Research Fund and the Richard Tam Foundation.
In addition to Ryan, the study's authors are Anastasia K. Yocum, Yuhua Zhang, Peisong Han, David F. Marshall, Paul T. Costa, Sarah H. Sperry, Takakuni Suzuki, Melvin G. McInnis, and Sebastian Zöllner. Costa co-developed both personality tests used in the studies along with Robert McCrae; the tests are published by PAR and available for licensed use .
Predictive evidence for the impact of personality styles on depression and functioning in two bipolar disorder cohorts, Journal of Affective Disorders, DOI: 10.1016/j.jad.2025.03.131
