Subthreshold bipolar disorder is a set of bipolar symptoms that don’t quite meet the definition of bipolar disorder. Think of it as “bipolar lite.” There is no single, agreed-upon definition for this disorder. For instance, if you need 3 symptoms to meet the criteria for a manic episode, sub-threshold bipolar disorder might be met with fewer symptoms, or require that the symptoms be met for a lesser period of time.
In other words, it’s a way of characterizing people as having a potential mental illness — but who do not yet have one.
The DSM — the reference book that defines mental disorders — is under revision for a new edition to be published next year. One of the considerations is subthreshold bipolar disorder.
Yet Mark Zimmerman, MD points out that this is probably a bad idea. And I’d have to agree.