A 2026 study of psychiatric outpatients in Tokyo found that anxious distress occurred at similar rates among people with major depression and bipolar disorder. The finding suggests that anxious distress, by itself, was not a reliable way to distinguish between the two conditions in this sample.
The study included 202 adults treated at seven outpatient clinics between January and December 2021. Of the participants, 133 had major depression and 69 had bipolar disorder.
Similar rates across the two groups
Anxious distress was identified in 42.9% of participants with major depression and 43.4% of those with bipolar disorder. The difference was not statistically significant, with a p-value of 0.95.
Participants completed the 22-item Clinically Useful Depression Outcome Scale with anxious distress items, or CUDOS-A. Each item was rated from 0, meaning “not at all,” to 4, meaning “almost every day.” Researchers counted anxious distress when a participant scored at least 2 on two or more of five symptoms.
Those symptoms included feeling keyed up or tense, unusual restlessness, difficulty concentrating because of worry, fear that something awful might happen, and feeling that one might lose control.
None of the 22 CUDOS-A items differed significantly between the diagnostic groups. Average total scores were 28.0 for the major-depression group and 27.0 for the bipolar-disorder group, a difference that was also not statistically significant.
Anxious distress tracked with greater depressive severity
Although anxious distress did not separate the two diagnostic groups, participants who had it reported more severe depressive symptoms within each group.
Among people with major depression, the average QIDS-SR depression-severity score was 15.0 for those with anxious distress, compared with 7.3 for those without it. Among people with bipolar disorder, the corresponding scores were 13.9 and 6.6. Both within-group differences had p-values below 0.001.
Overall depression severity did not differ between the major-depression and bipolar-disorder groups. The QIDS-SR was a separate self-report questionnaire used to measure depressive symptoms.
What the result does—and does not—show
Anxious distress is described in the DSM-5 as a specifier for depressive episodes with prominent anxiety. It is not a separate diagnosis, and it is distinct from anxiety disorders such as generalized anxiety disorder or panic disorder.
The study was cross-sectional, meaning participants were assessed at one point in time. It cannot show whether anxious distress causes more severe depression, predict later outcomes, or establish which symptoms came first.
The results also do not mean that anxiety-related symptoms are irrelevant when clinicians assess depression or bipolar disorder. The source notes that distinguishing bipolar depression from major depression depends on a person’s broader history, particularly any past periods of elevated mood or unusual energy, rather than anxiety symptoms alone.
Important limits on the findings
The bipolar group included 69 participants, so modest differences may have gone undetected. The study did not record the current mood state of participants with bipolar disorder, and it did not separate bipolar I from bipolar II.
Diagnoses came from routine clinical interviews rather than structured diagnostic interviews. Anxious distress was identified using a self-report cutoff rather than a clinician’s DSM-5 assessment, and the study did not evaluate different severity levels of anxious distress.
Medication use, illness duration and life stress were not fully accounted for. All participants were outpatients in the Tokyo metropolitan area, so the results may not apply in the same way to inpatients or people in other countries.
Some participants had mild or remitted symptoms. However, analyses limited to participants with QIDS-SR scores of 6 or higher produced virtually the same results.
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