Depression is the longest-lasting phase of bipolar disorder: signs that distinguish it from unipolar depression and delayed diagnosis

Most symptomatic weeks in bipolar disorder are depressive: in bipolar II, depression accounts for 50.3% of follow-up weeks, and hypomania for 1.3%.

🧭 Bipolar disorder (bipolar mood disorder) is often recognized by episodes of elevated mood. Yet in 146 patients with bipolar I disorder followed for an average of 12.8 years in the US, depressive symptoms accounted for 31.9% of weeks, while manic or hypomanic symptoms accounted for 8.9%. In bipolar II, 86 people were followed for 13.4 years; depressive symptoms were present during 50.3% of weeks.

🔍 In a patient association survey of 600 people, 69% of participants had initially been misdiagnosed, most commonly with unipolar depression. Those who were misdiagnosed had consulted an average of 4 physicians; more than one-third took 10 years or longer to receive the correct diagnosis. A meta-analysis of 27 studies found an average interval of 5.8 years between onset and initiation of treatment. No symptom definitively distinguishes the two, but excessive sleep, increased appetite, slowing of movement and thought, psychotic features, early onset, numerous episodes, and a family history of bipolar disorder increase the likelihood. Findings on antidepressants are inconsistent: one meta-analysis reported an increased risk of mania, whereas a randomized trial found that adding an antidepressant provided neither a benefit nor a difference in switching to mania or hypomania.

✅ Five steps: alongside periods of depression, describe days when you felt unusually energetic and slept little without feeling tired. Mention any family history of a bipolar diagnosis. If your depression began early, has recurred frequently, or has involved psychotic symptoms, ask about the possibility of bipolar disorder. Report any unusual increase in energy or activity after starting an antidepressant to your physician immediately. If the diagnosis is bipolar disorder, ask for skills-based psychoeducation alongside medication.

This content does not constitute diagnostic or treatment advice.

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Sachs ve ark. (2007), New England Journal of Medicine
Miklowitz ve ark. (2021), JAMA Psychiatry

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