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Old 18.01.2008., 01:25   #107
What Causes Bipolar Disorder?
Scientists are learning about the possible causes of bipolar disorder through several kinds of studies. Most scientists now agree that there is no single cause for bipolar disorder—rather, many factors act together to produce the illness.
Because bipolar disorder tends to run in families, researchers have been searching for specific genes—the microscopic “building blocks” of DNA inside all cells that influence how the body and mind work and grow—passed down through generations that may increase a person’s chance of developing the illness. But genes are not the whole story. Studies of identical twins, who share all the same genes, indicate that both genes and other factors play a role in bipolar disorder. If bipolar disorder were caused entirely by genes, then the identical twin of someone with the illness would always develop the illness, and research has shown that this is not the case. But if one twin has bipolar disorder, the other twin is more likely to develop the illness than is another sibling.6
In addition, findings from gene research suggest that bipolar disorder, like other mental illnesses, does not occur because of a single gene.7 It appears likely that many different genes act together, and in combination with other factors of the person or the person’s environment, to cause bipolar disorder. Finding these genes, each of which contributes only a small amount toward the vulnerability to bipolar disorder, has been extremely difficult. But scientists expect that the advanced research tools now being used will lead to these discoveries and to new and better treatments for bipolar disorder.
Brain-imaging studies are helping scientists learn what goes wrong in the brain to produce bipolar disorder and other mental illnesses.8,9 New brain-imaging techniques allow researchers to take pictures of the living brain at work, to examine its structure and activity, without the need for surgery or other invasive procedures. These techniques include magnetic resonance imaging (MRI), positron emission tomography (PET), and functional magnetic resonance imaging (fMRI). There is evidence from imaging studies that the brains of people with bipolar disorder may differ from the brains of healthy individuals. As the differences are more clearly identified and defined through research, scientists will gain a better understanding of the underlying causes of the illness, and eventually may be able to predict which types of treatment will work most effectively.
How Is Bipolar Disorder Treated?
Most people with bipolar disorder—even those with the most severe forms—can achieve substantial stabilization of their mood swings and related symptoms with proper treatment.10,11,12 Because bipolar disorder is a recurrent illness, long-term preventive treatment is strongly recommended and almost always indicated. A strategy that combines medication and psychosocial treatment is optimal for managing the disorder over time.
In most cases, bipolar disorder is much better controlled if treatment is continuous than if it is on and off. But even when there are no breaks in treatment, mood changes can occur and should be reported immediately to your doctor. The doctor may be able to prevent a full-blown episode by making adjustments to the treatment plan. Working closely with the doctor and communicating openly about treatment concerns and options can make a difference in treatment effectiveness.
In addition, keeping a chart of daily mood symptoms, treatments, sleep patterns, and life events may help people with bipolar disorder and their families to better understand the illness. This chart also can help the doctor track and treat the illness most effectively.
Medications
Medications for bipolar disorder are prescribed by psychiatrists—medical doctors (M.D.) with expertise in the diagnosis and treatment of mental disorders. While primary care physicians who do not specialize in psychiatry also may prescribe these medications, it is recommended that people with bipolar disorder see a psychiatrist for treatment.
Medications known as “mood stabilizers” usually are prescribed to help control bipolar disorder.10 Several different types of mood stabilizers are available. In general, people with bipolar disorder continue treatment with mood stabilizers for extended periods of time (years). Other medications are added when necessary, typically for shorter periods, to treat episodes of mania or depression that break through despite the mood stabilizer.
• Lithium, the first mood-stabilizing medication approved by the U.S. Food and Drug Administration (FDA) for treatment of mania, is often very effective in controlling mania and preventing the recurrence of both manic and depressive episodes.
• Anticonvulsant medications, such as valproate (Depakote®) or carbamazepine (Tegretol®), also can have mood-stabilizing effects and may be especially useful for difficult-to-treat bipolar episodes. Valproate was FDA-approved in 1995 for treatment of mania.
• Newer anticonvulsant medications, including lamotrigine (Lamictal®), gabapentin (Neurontin®), and topiramate (Topamax®), are being studied to determine how well they work in stabilizing mood cycles.
• Anticonvulsant medications may be combined with lithium, or with each other, for maximum effect.
• Children and adolescents with bipolar disorder generally are treated with lithium, but valproate and carbamazepine also are used. Researchers are evaluating the safety and efficacy of these and other psychotropic medications in children and adolescents. There is some evidence that valproate may lead to adverse hormone changes in teenage girls and polycystic ovary syndrome in women who began taking the medication before age 20.13 Therefore, young female patients taking valproate should be monitored carefully by a physician.
• Women with bipolar disorder who wish to conceive, or who become pregnant, face special challenges due to the possible harmful effects of existing mood stabilizing medications on the developing fetus and the nursing infant.14 Therefore, the benefits and risks of all available treatment options should be discussed with a clinician skilled in this area. New treatments with reduced risks during pregnancy and lactation are under study.
Treatment of Bipolar Depression
Research has shown that people with bipolar disorder are at risk of switching into mania or hypomania, or of developing rapid cycling, during treatment with antidepressant medication.15 Therefore, “mood-stabilizing” medications generally are required, alone or in combination with antidepressants, to protect people with bipolar disorder from this switch. Lithium and valproate are the most commonly used mood-stabilizing drugs today. However, research studies continue to evaluate the potential mood-stabilizing effects of newer medications.
• Atypical antipsychotic medications, including clozapine (Clozaril®), olanzapine (Zyprexa®), risperidone (Risperdal®), quetiapine (Seroquel®), and ziprasidone (Geodon®), are being studied as possible treatments for bipolar disorder. Evidence suggests clozapine may be helpful as a mood stabilizer for people who do not respond to lithium or anticonvulsants.16 Other research has supported the efficacy of olanzapine for acute mania, an indication that has recently received FDA approval.17 Olanzapine may also help relieve psychotic depression.18
• If insomnia is a problem, a high-potency benzodiazepine medication such as clonazepam (Klonopin®) or lorazepam (Ativan®) may be helpful to promote better sleep. However, since these medications may be habit-forming, they are best prescribed on a short-term basis. Other types of sedative medications, such as zolpidem (Ambien®), are sometimes used instead.
• Changes to the treatment plan may be needed at various times during the course of bipolar disorder to manage the illness most effectively. A psychiatrist should guide any changes in type or dose of medication.
• Be sure to tell the psychiatrist about all other prescription drugs, over-the-counter medications, or natural supplements you may be taking. This is important because certain medications and supplements taken together may cause adverse reactions.
• To reduce the chance of relapse or of developing a new episode, it is important to stick to the treatment plan. Talk to your doctor if you have any concerns about the medications.
Thyroid Function
People with bipolar disorder often have abnormal thyroid gland function.4 Because too much or too little thyroid hormone alone can lead to mood and energy changes, it is important that thyroid levels are carefully monitored by a physician.
People with rapid cycling tend to have co-occurring thyroid problems and may need to take thyroid pills in addition to their medications for bipolar disorder. Also, lithium treatment may cause low thyroid levels in some people, resulting in the need for thyroid supplementation.
Medication Side Effects
Before starting a new medication for bipolar disorder, always talk with your psychiatrist and/or pharmacist about possible side effects. Depending on the medication, side effects may include weight gain, nausea, tremor, reduced sexual drive or performance, anxiety, hair loss, movement problems, or dry mouth. Be sure to tell the doctor about all side effects you notice during treatment. He or she may be able to change the dose or offer a different medication to relieve them. Your medication should not be changed or stopped without the psychiatrist’s guidance.
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