PMDD differs from PMS in that emotional symptoms in PMDD are more serious and severe than in PMS, although physical symptoms are relatively similar. PMDD can lower quality of life to an extent quite similar to that of major depression, and can also be associated with an increase in suicidal ideation and suicide attempts. Approximately 5-10% of PMS sufferers also have PMDD. It affects 3 to 8% of women in their reproductive years worldwide, and is a source of huge burden on women and their families. Women with seasonal affective disorder (SAD) are more likely to have PMDD than women in the general population.

The exact cause of PMDD is unknown; however, several theories have been proposed. One of such theories suggests that PMDD is due to the lack of serotonin (a substance found naturally in the brain and involved in sleep, depression, memory, and other neurological processes). Serotonin acts as a calming hormone; therefore when serotonin levels are low, symptoms such as pain, irritability, anger, food cravings, and anxiety are precipitated. Once serotonin levels are restored, many of these symptoms disappear.

PMDD symptoms include at least one of the following:
1. Feeling sad, worthless or hopeless.
2. Feeling tense, anxious or ‘on edge’.
3. Feeling overwhelmed or out of control.
4. Mood swings, emotional outbursts or unexplained crying.
5. Irritability, anger, or short temper.
6. Increased appetite (carbohydrate cravings)
It also includes other common symptoms of depression such as sleep problems, changes in appetite or weight, difficulty in concentrating, lack of interest in activities once enjoyed, and having suicidal thoughts. Physical symptoms are similar to that in PMS, breast tenderness, bloating, weight gain, headaches/backaches, and skin problems such as acne.

The first-line treatment for PMDD has been anti-depressants. However, these can be intolerable or result in serious adverse effects, especially in adolescents. Bright Light Therapy has been proposed as a non-pharmacological treatment, amongst other such treatments, to help increase serotonin levels and production, and may represent a safe and attractive alternative. According to Terman & Terman (2005), patients with both seasonal and nonseasonal PMDD, or milder PMS have responded favourably to 1 week of bright light therapy, in a series of clinical trials. The effect of bright light is thought to be mediated through increased production of melatonin, which subsequently boosts serotonin levels. For women seeking a non-pharmacological and safe treatment for PMDD, light therapy is a promising treatment with great prospects.

HealthyPlace.com – Depression Community: Premenstrual Dysphoric Disorder (PMDD): healthyplace.com/communities/depression/pmdd.asp
References
1. Light therapy. PMS & Premenstrual Dysphoric Disorder (PMDD). lighttherapy.com.au/pms.php. Accessed: 23/08/2007.
2. Lam RW, Carter D, Misri S, Kuan AJ, Yatham LN, Zis AP. A controlled study of light therapy in women with late luteal phase dysphoric disorder. Psych Res 1999; 86: 185-192.
3. Terman M, Terman JS. Light Therapy. In: Principles and Practice of Sleep Medicine (2005). Ed by Kryger MH, Roth T, Dement WC. 4th Ed. Elsevier. Philadelphia. Pp 1424-1442.
4. Krasnik C et al. The effect of bright light therapy on depression associated with premenstrual dysphoric disorder. Am J Obstet Gynecol 2005; 193: 658-661.
5. Liang BA et al. Recognizing and Treating Premenstrual Dysphoric Disorder. Hosp Physician 2003. Turner-white.com/pdf/hp_aug03_disorder.pdf. Accessed: 23/08/2007.