How is bipolar disorder diagnosed?

DEAR DR. ROACH » How do you diagnose bipolar disorder? Do you need a blood test, or can it be diagnosed by a person’s actions?

— A.Y.

DEAR READER » Bipolar affective disorder, formerly called manic-depressive illness, is a psychiatric condition that is frequently misdiagnosed. Over a third of people diagnosed with bipolar disorder waited at least 10 years between seeking treatment for their symptoms and receiving a correct diagnosis.

The diagnosis is made clinically, meaning based on a thorough psychiatric history and exam, but also includes a medical evaluation to be sure there is not a medical condition underlying (or mimicking) the diagnosis.

The major criteria for making the diagnosis of bipolar disorder include depressive symptoms or symptoms of elevated mood. Elevated mood comes in two closely related clinical types: mania and hypomania. With both of these, people have high levels of energy and activity, and an elated or irritable mood. The person must have several of these defining symptoms:

People with mild or moderate changes are called “hypomanic.” When these changes are severe enough to caused marked impairment in their work or social life, or require hospitalization, or when people have beliefs that are not based in reality at all (psychosis), it is called “mania.” The doctor making the diagnosis must carefully exclude the possibility that these changes are as a result of a different medical condition or related to drug use. For this reason, blood tests are necessary. They do not make the diagnosis (there is no blood test to confirm the diagnosis), but they rule out other causes (thyroid toxicosis may have some similar features, for example).

Many people with bipolar disease have predominantly symptoms of depression, with only one or few relatively mild hypomanic episodes. This is referred to as bipolar 2 disorder. Also, some people will have what looks like major depression and develop manic or hypomanic symptoms during treatment for depression: this is bipolar disease as well, and one important reason that a person being treated for depression needs close follow-up. Depression is occasionally called “unipolar major depression” to distinguish it from bipolar disorder.