In the United States, about 3.9 percent of the adult population has a lifetime prevalence of bipolar disorder, according to the National Institute of Mental Health.
Individuals with bipolar disorder, also called manic depressive disorder, have periods of unusually high mood (mania) and low mood (depression).
Symptoms of mania include an overly-happy mood or an irritable mood, restlessness, talking very fast, and participating in high-risk behaviors. Individuals who are manic may be easily distracted, sleep little, and have unrealistic beliefs about their abilities.
Symptoms of depression include a loss of interest in activities, low mood, trouble concentrating, and feeling tired. Individuals who are depressed may have thoughts of suicide or attempt suicide.
There are several types of bipolar disorder.
The first is bipolar I disorder, in which the individual has manic or mixed (manic and depressive symptoms occurring together) symptoms that occur for seven or more days, or has severe enough symptoms that require hospitalization.
Individuals with this type of bipolar disorder also have symptoms of depression.
With bipolar II disorder, patients do not have full mania. Instead, they experience hypomania, which is an elevated mood that is not as extreme as mania.
Individuals with bipolar II disorder also have symptoms of depression.
Individuals may be diagnosed with cyclothymia, in which they have symptoms of hypomania and mild depression.
If an individual is diagnosed with bipolar disorder NOS (not otherwise specified), she has symptoms of bipolar disorder, but she does not meet full criteria for bipolar I disorder or bipolar II disorder.
The National Institute of Mental Health noted that bipolar disorder NOS may be diagnosed if the duration of symptoms is not long enough or the individual has fewer symptoms than needed to meet full criteria.
To diagnose either bipolar I disorder, bipolar II disorder, cyclothymia or bipolar disorder NOS, the individual needs to present with certain symptoms.
But new research indicates that brain imaging may identify an individual who is at risk for developing bipolar disorder before any clinical signs appear.
The study, which was conducted by researchers from the Black Dog Institute and the University of New South Wales in Australia, used functional magnetic resonance imaging (fMRI) to see participants’ brain activities when they were shown pictures of different emotions.
Participants saw three different emotions: calm (the neutral stimulus), happy and fearful.
The experimental group was made up of 47 individuals aged 18 to 30 who were genetically high-risk for bipolar disorder. They had at least one first-degree relative with the disorder. Their data were compared to 49 controls who were in the same age range but did not have a family history of either bipolar disorder or another severe mental illness.
Individuals who were genetically high-risk for bipolar disorder had significantly reduced activity in the inferior frontal gyrus, an area of the brain that regulates emotional responses.
In a news release from the University of New South Wales, author Philip B. Mitchell, M.D. said, “Our results show that bipolar disorder may be linked to a dysfunction in emotional regulation and this is something we will continue to explore. And we now have an extremely promising method of identifying children and young people at risk of bipolar disorder. We expect that early identification will significantly improve outcomes for people that go on to develop bipolar disorder, and possibly even prevent onset in some people.”