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Bipolar disorder, formerly known as manic depressive disorder, is a recurrent psychiatric illness characterized by recurring episodes of mania and depression. There can be extreme shifts in mood, energy level, thinking, and daily functioning and activities. Bipolar patients require lifelong treatment to control their symptoms. Bipolar disorder affects 2.6% of the US population over the age of 18 and has a lifetime prevalence of 1%.1-2 Bipolar disorders are more common in women.2 The mean age of onset for bipolar disorder is 21 and often begins in adolescence or early adulthood.2 There is a high comorbidity of substance use disorders in bipolar disorders.

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Pathophysiology

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The exact cause of bipolar disorder is unknown; however, there is evidence that a chemical imbalance with several neurotransmitters is involved in its pathophysiology. It is thought that there may be an excess of norepinephrine and dopamine in mania, whereas there may be a deficiency of serotonin, norepinephrine, and dopamine in depression. Medications used to manage the symptoms of bipolar disorder alter the transmission of serotonin, dopamine, norepinephrine, as well as gamma-aminobutyric acid (GABA), glutamate, and aspartate.

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Family, twin, and adoptions studies provide strong evidence for a major genetic contribution to the risk of developing bipolar disorder. Identifying that bipolar disorders tend to run in families has led to the identification of candidate genes interacting to play a role in determining illness susceptibility.

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Clinical Presentation and Diagnosis

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Discrete types of mood episodes are classified as manic, hypomanic, depressive, or mixed type. Mania is the unique hallmark of bipolar disorder. The signs and symptoms of mania include an elated, euphoric, expansive, or irritable mood; increased self-esteem or grandiosity; a decreased need for sleep; more talkative or pressured speech; racing thoughts or flight of ideas; distractibility; increased goal-directed activities; and psychomotor agitation. The patient may also report an increase in risk-taking behaviors or excessive involvement in pleasurable activities without thinking about the consequences of engaging in such activities (ie, sexual promiscuity, unrestrained buying sprees). Three or more of these associated symptoms must be present in a given patient if his/her mood is euphoric or expansive; four or more if the mood is irritable.3 These symptoms must last at least 1 week or can be of any duration if hospitalization was required. During a manic episode, people with bipolar disorder engage in unsafe behaviors that may result in hospitalization and incarceration. Psychosis may sometimes accompany a manic episode. Hypomania is a less severe form of mania, lasting at least 4 days and not requiring hospitalization. These patients may describe that they feel more creative, important, and productive and do not think that they need any kind of medical treatment. A depressive episode may alternate with manic episodes, and the patient would be said to have bipolar depression (as opposed to unipolar depression, otherwise known as major depressive disorder; see Chapter 53, Depression). ...

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