The psychiatrist who split bipolar disorder from unipolar depression went on to argue that they belong on one spectrum
Splitting Unipolar and Bipolar
Jules Angst died in May 2026 at the age of 99. He was born the same year that Emil Kraepelin died. Kraepelin was the first to separate manic-depression from schizophrenia, and spent of his life trying to split manic depression into its bipolar and unipolar sides. At last, he was unable to, concluding:
“This classification, apparently so simple, really encounters manifold difficulties.”
Angst picked up that cause in the 1960s. Along with Carlo Perris, he recognized that the two mood disorders differ in their family histories and response to treatment. His proposed division was picked up in DSM-III (1980), the first edition to separate bipolar from unipolar mood disorders.
Bringing Them Back Together
Within months of the publications, psychiatrists wrote letters decrying the split as premature. Both responded to lithium; both had similar EEG findings; and they overlapped in family histories and symptoms (eg, mixed states). Angst saw both sides, and spent the rest of his career filling in the gaps in the “bipolar spectrum” — the mixed features, cyclical depressions, and brief hypomanias that don’t cross the threshold for full bipolarity.
His work was gradually adopted in subsequent editions of the DSM, first with bipolar II in DSM-IV (1994), and later with a fuller spectrum in DSM-5 (2013):
Mood disorders occur occur on a spectrum, from bipolar I to pure depression, but they can also be boxed into categories as shown above. Where we draw the line between unipolar and bipolar is arbitrary. DSM-5 draws it at the red/blue divide at top, but studies from Angst and others point to the orange/blue divide at bottom.
Angst may be the only psychiatrist who revolutionized the DSM twice. His categorical divide colored DSM-III, and his spectrum view was echoed by David Kupfer, Chair of DSM-5, who wrote that depression and bipolar are part of “a continuum, with variable expressions of vulnerability to hypomania or mania.”
The distinction is not just theoretical. In his BRIDGE study, Angst and colleagues showed that the risk of mood switching on an antidepressant rises with the duration of past hypomania. In this graph, only the two bars at right have DSM-5 bipolar disorder, but the risk is there for the spectrum patients as well (they would be in the orange bar above).
The Bipolar-Normal Continuum
Angst also recognized the that hypomania occurred on a continuum, with varying degrees of intensity from normal to bipolar and no clear dividing line between them. He followed two landmark cohorts, a hospitalized affective disorder cohort and a normal community sample, for over five decades. But as he looked closer at these “normals” who had hypomanic symptoms without depression, he found their lives were not always so chipper. They were more irritable and impulsive, with higher rates of sleep problems, substance use, and binge eating.
Other Contributions
Angst worked into his 90s. His papers are richly detailed and practical. Many have multiple findings that could be plucked out as papers on their own, like the spectrum of antidepressant response above, which was buried in a table of the larger BRIDGE study.
- Angst provided the statistical backbone for the first international lithium prophylaxis data, defending Mogens Schou’s before-and-after evidence against critics who wanted randomized trials first. Lithium later became the only mood stabilizer to meet a strict four-part efficacy standard: acute mania, acute depression, and prevention of both.
- He identified Recurrent Brief Depression and showed that its overlap with major depression signals a subgroup at sharply higher suicide-attempt risk.
- He developed the Hypomania Checklist (HCL-32), a widely used bipolarity screening tool, later refined into the HCL-33.
- His BRIDGE study removed the duration cutoffs used to diagnose hypomania, revealing mixed depressive states tied to antidepressant-induced mania and heavier family loading for bipolar disorder.
- In one of the BRIDGE papers, Angst showed that the long-recognized link between depression alcohol use disorders was entirely due to mixed features. The association disappeared when patients with mixed features were removed.
Legacy
Angst kept revising his own conclusions as new data arrived. His arc, from splitting mood disorders apart to arguing they belong on a spectrum, still shapes today’s debates over where unipolar depression ends and bipolarity begins.
—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report
