Bipolar disorder is a mood disorder that causes symptoms of both mania and depression in patients. As classified in the Diagnostic and Statistical Manual of Mental Disorders, or DSM-IV, symptoms of bipolar disorder must last for at least 2 weeks and have an impact on the patient's quality of life. The cause of bipolar disorder is not known, but it may be due to a neurotransmitter imbalance in the patient's brain. Bipolar disorder affects only a small percentage of the United States population, according to the National Institutes of Health.
Causes
According to the Child and Adolescent Bipolar Foundation, the exact cause of bipolar disorder is unknown. Neuroscientists believe that bipolar disorder is caused by a chemical imbalance in the brain. Two neurotransmitters, serotonin and norepinephrine, are highly involved in the regulation of mood and pleasure. In bipolar disorder patients, the levels of serotonin and norepinephrine fluctuate. When levels of the neurotransmitters are low, depression symptoms appear. When the levels of the neurotransmitters are high, mania symptoms appear.
Depression
Depression is the lower spectrum of the symptoms of bipolar disorder. According to the Child and Adolescent Bipolar Foundation, symptoms of depression in bipolar disorder patients include feelings of self-hate, worthlessness and sadness, thoughts of suicide and death, sleeping problems, lack of interest in her favorite activities and withdrawal from family and friends. Bipolar disorder patients who mainly have depression symptoms are diagnosed with bipolar disorder type II.
Mania
Mania is the higher spectrum of the symptoms of bipolar disorder. According to the Child and Adolescent Bipolar Foundation, symptoms of mania include hallucinations, psychosis, decreased need for sleep, euphoria, grandiosity, risky activity participation, very distracted, irritability, racing thoughts and extreme talkativeness. Patients who have mainly symptoms of mania are diagnosed with bipolar disorder type I.
Prevalence
According to the National Institutes of Health, around 5.7 million adults in the United States are diagnosed with one of the types of bipolar disorder. This equals to 2.6 percent of the United States population 18 and older. The median onset age for bipolar disorder is age 25, though bipolar disorder can start early in childhood as well.
Note
Besides bipolar disorder type I and type II, there are two other forms of bipolar disorder, according to the Child and Adolescent Bipolar Foundation. Patients who have bipolar disorder NOS, or not otherwise specified, have severe symptoms, but it cannot be described as either type I or type II. Cyclothymia, on the other hand, is a weaker form of bipolar disorder that still impairs the patient's life.
