What is PMS?
Premenstrual syndrome, or PMS for short, is a combination of severe symptoms that occur every month before menstruation. It is also known as premenstrual tension or PMT. Most women notice a change in their mood or physical state before the onset of menstruation (period). These symptoms may not be the same every month and depending on external factors, it may be mild to severe. These minor symptoms fall under the term menstrual molimina, which is synonymous with mild premenstrual syndrome. A small percentage of women regularly have more severe cyclical physical and psychological symptoms each month that cause a major disruption to their lives. When this occurs, it is known as premenstrual syndrome (PMS) or premenstrual tension (PMT). At the extreme end of the spectrum is a condition known as premenstrual dysphoric disorder (PMDD). This is the most severe form of PMS. Women suffering from PMDD tend to have severe psychological changes such as depression, irritability, anger, and tension before the start of their periods every month.
What does PMS mean?
The exact cause of PMS is unknown. Therefore the significance of PMS has never been ascertained. It has been noted that women in their 30s and 40s tend to have more severe symptoms, which markedly improve when using combined oral contraceptive pills. Typically, PMS occurs during the luteal phase of the menstrual cycle, which occurs just after ovulation. PMS is most common in the last 7 to 10 days of the cycle. The symptoms disappear with the onset of menstruation and there is at least one symptom-free week afterwards. These findings have contributed to various hypotheses about the causes of PMS.
Symptoms of Premenstrual Syndrome
The classic criteria for PMS require that the symptoms should occur in the second half of the menstrual cycle, with at least seven symptom-free days in the first half of the cycle. The symptoms must occur in 3 consecutive menstrual cycles and must be severe enough to require medical advice or treatment. The typical symptoms of PMS are of two types :
- Edema (swelling caused by fluid in the body’s tissues)
- Weight gain
- Breast swelling and/or pain – cyclical mastalgia
- Decreased libido
- Conditions such as epilepsy, migraine, and asthma may get worse before a period.
- Emotional lability or mood swings
- Sleep changes
- Decreased ability to concentrate
- Cravings particularly of sweets
The respite from symptoms offered during pregnancy may be short lived as women suffering from PMS are more likely to suffer from postpartum depression.
Causes and Risk Factors of Premenstrual Syndrome
The exact cause of PMS is unknown. As a result, many theories have been put forward. The Rapkin hypothesis puts forward the following observations :
- There is no evidence that ovarian events are responsible for PMS by causing progesterone deficiency.
- Altering the levels of circulating estrogen and progesterone artificially may induce PMS in women prone to PMS, but not in previously well women.
- Although ovulation is a prerequisite for PMS/PMDD, studies suggest that events occurring in the brain, and not in the ovaries, are to be held responsible for PMS. There seems to be an abnormal CNS response to normal progesterone levels occurring in the luteal phase.
- Certain metabolites or breakdown products of progesterone, such as allopregnanolone and pregnenolone are psychoactive (substances that affect the brain functioning, causing changes in mood, behavior and consciousness).
- Neurons in women with PMS preferentially metabolize progesterone to pregnenolone (which heightens anxiety) rather than allopregnanolone, which is anxiolytic (relieves anxiety).
- Although allopregnanolone is anxiolytic, low levels may contribute to anxiety.
Various other points to be noted are :
- The typical symptoms of PMS cannot always be attributed to salt and water retention, but edema and weight gain may be caused by fluid overload.
- Similarly, it is unlikely that hormonal changes that occur in the late luteal phase of the menstrual cycle could be responsible, since even on early termination of the luteal phase and production of menstruation by drugs such as mifepristone, the time course and severity of symptoms are not modified.
- Studies suggest that there is a hereditary factor involved. PMS, PMDD, major depressive disorder (MDD), postpartum depression, and anxiety disorders may co-exist in family members.
- Past history of depression may be a risk factor for PMS.
- Role of calcium metabolism in the development of PMS/PMDD – there is lower ionized serum calcium during the menstrual phase in women susceptible to PMS/PMDD than in asymptomatic women.
- Imbalances in both calcium and magnesium levels are thought to bring on symptoms of PMS.
- Oversensitivity to progesterone may reduce the level of serotonin, a neurotransmitter (chemical messenger in the brain) involved in regulating moods, appetite, and sleep cycles amongst its other functions. Low levels of serotonin are often seen in women suffering from PMS/PMDD.
- It has been suggested that prostaglandins (substances responsible for features of inflammation such as pain, swelling, warmth, and redness) may be involved in producing symptoms such as breast tenderness, bloating, cramps, and constipation in PMS.
- Obesity, smoking, poor diet, and lack of exercise may be risk factors for PMS.
Article reviewed by Dr. Greg. Last updated on April 14, 2011