American Medical Association Family Medical Guide - American Medical Association [456]
Rapid Cycling and Cyclothymia
Rapid cycling is a form of bipolar disorder in which the episodes of mania and depression occur at least four times a year. In serious cases (called ultrarapid cycling), the episodes can occur several times a day. Up to 20 percent of all people with bipolar disorder develop rapid cycling at some point in their lives, and 90 percent of those who do are women. Rapid cycling is more common in people with bipolar disorder who have a thyroid abnormality.
Lithium is less effective in treating rapid cycling than other forms of bipolar disorder, and antidepressant medications sometimes induce rapid cycling. For these reasons, an antiseizure medication called divalproex is usually used instead; divalproex works by stabilizing the limbic system (the areas of the brain responsible for emotions). Thyroid hormone also may be helpful in treating rapid cycling in people with mood disorders who have thyroid abnormalities.
Cyclothymia is a disorder marked by less severe episodes of mania and depression than bipolar disorder, and the episodes last only a few days. The instability produced by these milder episodes of mania can cause such erratic behavior as frequent changes of residence, irregular work attendance, repeated romantic breakups, and an intermittent pattern of alcohol and drug abuse. A rare form, called chronic hypomania, causes predominantly manic episodes and produces a personality that is overly cheerful, impulsive, and excessively energetic.
People with cyclothymia have a greater risk of developing bipolar disorder than the general population, but only a third actually go on to develop it. Treatment may not be required for cyclothymia if the person can learn to live within the extremes of his or her temperament. Otherwise, a doctor will prescribe mood stabilizers (see page 713).
To help treat your bipolar disorder, your doctor will recommend one or more types of psychotherapy to give you support and guidance in coping with the disorder. You and family members may also benefit from joining a support group to share experiences with other people who are going through the same difficulties.
Seasonal Affective Disorder
Seasonal affective disorder (SAD) is a form of depression that occurs in the fall or winter in response to shorter days with less sunlight. The disorder subsides in the spring or summer as daylight increases. The exact cause of SAD is unclear. The deficiency of light during fall and winter is thought to decrease the level in the brain of the chemical messenger serotonin. Serotonin affects emotions, behavior, and thought. People with SAD may also have altered circadian rhythms, or internal biological clocks, that cause a shift in the signals that indicate when to fall asleep and when to wake up.
Normally, the light-sensing pineal gland in the brain responds to the lessening light of day by secreting the hormone melatonin, which promotes relaxation and sleep. Daylight signals the pineal gland to shut off the production of melatonin to allow us to wake up. Melatonin levels should be low in the morning and high at bedtime, but melatonin is produced in increased quantities throughout the day in winter, when the days are shorter and darker. Maintaining this cycle becomes more difficult in the fall and winter because the body is