Bipolar disorder is also sometimes referred to as manic depression. The defining characteristic of bipolar disorder is alterations in mood between manic and depressive stages. Both the manic and the depressive stages of bipolar disorder are disruptive in one’s life. There are two categories of bipolar disorder based on the severity of the manic stage. Bipolar I disorder is characterized by a severe manic stage and bipolar II disorder is characterized by a less severe manic stage known as hypomania (Kessler, 2005).
Family history and identical twin studies have shown that bipolar disorder has a strong genetic component. These are some of the most replicated findings in postmortem studies of patients with bipolar disorder (Benes, 2011).
One of the many theories of the abnormalities of hippocampus and thalamus in bipolar disorder is that there is improper regulation of the γ-Aminobutyric acid (GABA) neurons in the hippocampus that leads to the development of bipolar disorder (Benes, 2010, Bhagwagar 2007). With limited amounts of GABA produced in bipolar disorder, GABA is unable to inhibit pyramidal neurons, which could then lead to an increased serotonergic and dopaminergic excitatory state.
Another theory of the mechanism of bipolar disorder behind the abnormal activation of thalamus and hippocampus is abnormalities in the glutamatergic signaling pathways. These studies all show there are there is a disruption of the limbic system in bipolar disorder.
Since biology of bipolar disorder is not well understood, the disorder is diagnosed based on the symptoms of both the manic and depressive stage. To be considered bipolar I disorder the patient must be in a manic state for at least one week or be hospitalized for the mania (American Psychiatric Association, 2013).
To be considered bipolar II disorder the patient must be in a manic state for at least four days (American Psychiatric Association, 2013). Bipolar disorder can be easily mistaken for major depression since individuals are more likely to seek help when they are depressed than when experiencing mania (American Psychiatric Association, 2013).
The symptoms of bipolar disorder can be treated but it cannot be cured. Furthermore, bipolar disorder results in about a decade reduction in expected life span, with as many as one in nine patients completing suicide (Lawrence, 2013).
Bipolar disorder damages not only a person’s quality of life, but can have devastating consequences such as suicide.
