Light Therapy

Light treatment also significantly reduces depressive symptoms in patients with PMDD.^31,32 These patients remain well for up to four years on the light treatment, but relapse is likely if the light treatment is discontinued. Our laboratory also has been researching the efficacy of light treatment for childhood and adolescent depression.⁴⁵ Preliminary evidence suggests similar therapeutic effects of light; however, more work in this area is necessary.

The effects of light therapy may be mediated through melatonin. Melatonin is probably one of the best markers for circadian rhythms in humans; it is not as affected by stress, diet, or exercise as other circadian hormonal markers are. During four different phases of the menstrual cycle - the early follicular, late follicular, mid-luteal, and late luteal - women with PMDD have a lower or blunted amplitude of the melatonin rhythm, which is an important regulator of other internal rhythms.⁴⁶ This finding was replicated in a larger study.⁴³ Light treatment may improve women's mood, but the melatonin rhythm is still very blunted.

Light is perceived or responded to differently in patients with premenstrual depression compared with normal control subjects.³⁹ In the luteal phase, the melatonin rhythm does not advance in response to morning bright light as it does for normal control subjects. Instead, patients with premenstrual depression either have no response to the light or their melatonin rhythm is delayed, in the opposite direction. These findings suggest that women with PMDD have an inappropriate response to light, which is critical to synchronize rhythms. The result may be that circadian rhythms become desynchronized, thereby contributing to mood disturbances in PMDD.

Postpartum Affective Illness

The postpartum period is a highly vulnerable time for the development of mood disorders. Three postpartum psychiatric syndromes are recognized and distinguished by symptoms and severity:

1. "Maternity blues" is a relatively mild syndrome characterized by rapid mood shifts; it occurs in up to 80% of women and, therefore, is not considered a psychiatric disorder.
2. A more severe depressive syndrome with melancholia is experienced by 10% to 15% of postpartum women.
3. Postpartum psychosis, the most severe syndrome, is a medical emergency.

Postpartum depression has been recognized in the DSM-IV, although the criteria for the onset of depressive symptoms within four weeks postpartum are too limiting to be clinically accurate. Studies by Kendall and colleagues⁴⁷ and Paffenbarger⁴⁸ indicate a relatively low incidence of mental illness during pregnancy but a very dramatic rise within the first few months postpartum.

The Marc Society, an international organization for the study of psychiatric illness related to childbearing, recognizes the time of vulnerability for postpartum depression and psychosis as one year after delivery. The early episodes of postpartum psychiatric symptoms (occurring within four weeks of delivery) are often characterized by anxiety and agitation. Depressions that have a more insidious onset may not peak until three to five months postpartum and are characterized more by psychomotor retardation. Three to five months postpartum is also the peak time of postpartum hypothyroidism, which occurs in about 10% of women.¹⁴ Postpartum hypothyroidism can be predicted early in pregnancy by measuring thyroid antibodies.⁴⁹

The risk of developing postpartum psychosis is 1 in 500 to 1 in 1000 for the first delivery but increases to 1 in 3 for subsequent deliveries for those women who had it with the first delivery.⁴⁷ Unlike postpartum mood disturbances, postpartum psychosis has an acute onset. In addition to having had a previous psychotic episode, those at increased risk for developing postpartum psychosis include women who are primiparous (bearing one child), have a personal history of postpartum depression or a family history of a mood disorder, and are over 25 years of age.

In general, postpartum psychiatric episodes are characterized by a young age of onset, an increased frequency of episodes, decreased psychomotor retardation, and more confusion, which often complicates the diagnostic picture. Women with postpartum psychiatric disorders often have a family history of mood disorders. In those women with a previous history of a postpartum depression, there is at least a 50% chance of recurrence.⁵⁰ There is also a high likelihood of recurrence of depression outside the postpartum period.⁵¹ Some of the studies conducted before effective treatments were available followed these women longitudinally and found an increased incidence of depressive relapse at menopause.⁵²

References