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Distinguishing Between Bipolar I Disorder and Bipolar II Disorder
(Part 2 of 4)
In this video, Joseph F. Goldberg, MD, explains some key distinctions between bipolar I disorder and bipolar II disorder and treatment implications of the differences. He also discusses the concept in his session titled "Bespoke Psychopharmacology: Tailoring Individualized Pharmacotherapy for Patients with Bipolar Disorder" being presented at the 2021 Psych Congress Regionals meeting series, which continues April 23 and 24 and May 21 and 22.
Dr. Goldberg, Clinical Professor of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York, is a Bipolar Disorders Section Editor for the Psychiatry and Behavioral Health Learning Network.
There's still a lot of debate about bipolar I and bipolar II disorder, starting with diagnostic clarity. In the DSM field trials, bipolar I mania had just about the best interrater reliability among diagnosticians, and bipolar II had among the lowest.
It can be hard to tease out. Many of the symptoms are common during highs in terms of energy, sleeplessness, speediness, and so on, but the fundamental distinctions are that hypomanias don't cause trouble. They don't cause psychosis. They don't cause hospitalization, and they are a departure from the baseline. Someone who is just bubbly and effervescent or hyperthymic as a baseline isn't really having an episode. You want to differentiate what their baseline is from an episode.
Hypomanias are different from normal cheerful baselines. It's the elements of psychomotor acceleration and speediness and overactivity that's different from depression, but also different from someone's norm. That can make it easier to miss, especially when one considers that depressions are so dominant over time in people with bipolar II disorder.
Follow-up studies tell us, if you count out the amount of time spent up versus down in a bipolar I patient, it's about a 3-to-1 ratio of downtime to uptime, whereas in bipolar II disorder, it's closer to a 40-to-1 ratio of downtime to uptime.
An innocuous-seeming hypomania that doesn't cause personal, financial, social, or other complications may get missed. Since depression's often underdiagnosed—bipolar depression's often underdiagnosed as unipolar depression—if you blink, you can miss the diagnosis, because the hypomania goes by fast, and it's not that notable. That's one piece.
Second piece is it really is a distinct entity. Some people diagnosis bipolar II in a little more ambiguous way, like, "I'm not really sure about the diagnosis." We don't want to see it become a wastebasket for people that just get agitated with an antidepressant but don't have the other symptom criteria, or people who, there's substance use in the picture, "I'm not really sure what to call this," and so it's in the spectrum. It's really meant to be a very distinct phenomenon where the highs are just not as damaging as they are in full-blown manias, and they lack the psychosis.
Last, but not least, the depressions are so dominant in bipolar II disorder. This is a really big area, is how best to treat bipolar II depression. At the moment, all of our FDA-approved treatments, or nearly all of them, are targeted to bipolar I depression.
Quetiapine has some data in bipolar II. Lamotrigine has some data in bipolar II, but it's a much more off-label area. To the extent antidepressants have value in bipolar depression, at least some of them seem to have more of a place in bipolar II depression than bipolar I depression.
We could talk at great length about the distinctions, but those are some of the more important ones I would point out.
More with Dr. Goldberg: Using Moderators and Mediators to Tailor Bipolar Disorder Treatment
