Two to ten percent of women have significant premenstrual symptoms that are separate from the normal discomfort associated with menstruation in healthy women.^[1][2]

Culturally, the abbreviation PMS is widely understood in English-speaking countries to refer to difficulties associated with menses, and the abbreviation is used frequently even in casual and colloquial settings, without regard to medical rigor. In these contexts, the syndrome is rarely referred to without abbreviation, and the connotations of the reference are frequently more broad than the clinical definition.

Premenstrual dysphoric disorder (PMDD) consists of symptoms similar to, but more severe than, PMS, and while primarily mood-related, may include physical symptoms such as bloating. PMDD is classified as a repeating transitory cyclic disorder with similarities to unipolar depression, and several antidepressants are approved as therapy.^[

More than 200 different symptoms have been associated with PMS, but the three most prominent symptoms are irritability, tension, and dysphoria (unhappiness).^[1] Common emotional and non-specific symptoms include stress, anxiety, difficulty in falling asleep (insomnia), headache, fatigue, mood swings, increased emotional sensitivity, and changes in libido.^[4] Formal definitions absolutely require the presence of emotional symptoms as the chief complaint; the presence of exclusively physical symptoms associated with the menstrual cycle, such as bloating, abdominal cramps, constipation, swelling or tenderness in the breasts, cyclic acne, and joint or muscle pain—no matter how disruptive these physical symptoms are—is not considered PMS.^[5]

The exact symptoms and their intensity vary significantly from woman to woman, and even somewhat from cycle to cycle. Most women with premenstrual syndrome experience only a few of the possible symptoms, in a relatively predictable pattern.^[6] For example, one woman with PMS may be anxious and tense for three or four days before her menstrual period begins, and this will happen with only small variations each cycle, such as being somewhat more tense (or less tense) than in previous cycles.

Women with PMS do not experience completely different symptoms each cycle, such as anxiety with one cycle, depression the next, anger in the following cycle, and so forth. Each woman with PMS has her own personal pattern of symptoms.^[6] While one woman might be anxious and tense, another woman might experience PMS as causing her to be depressed and tearful for two days each cycle, and another woman might find that she is easily irritated by problems that she normally considers minor. Each woman's pattern, although different from what other women with PMS experience, will be relatively predictable and stable for the woman who experiences it.

Under typical definitions, symptoms must be present at some point during the ten days immediately before the onset of menses, and must not be present for at least one week between the onset of menses and ovulation.^[5] Although the intensity of symptoms may vary somewhat, most definitions require that the woman's unique combination of symptoms be present in multiple, consecutive cycles.^[5]

Risk factors[edit]

• High caffeine intake^[5]
• Stress may precipitate condition
• Increasing age
• History of depression
• Family history
• Dietary factors^[7] (Low levels of certain vitamins and minerals, particularly magnesium, manganese, zinc,^[8] vitamin E and also Vitamin D)

There may be a genetic aspect to the probability of having premenstrual syndrome: it has been shown that the likelihood of both identical twins suffering from PMS is higher than with fraternal twins.^[1] This means that if one twin has PMS, then the other twin is more likely than average to have PMS, pointing to a genetic component.

B vitamins, in particular vitamin B6, can also assist with PMS.^[9]

Diagnosis[edit]

There is no laboratory test or unique physical findings to verify the diagnosis of PMS. The three key features are:^[1]

• The woman's chief complaint is one or more of the emotional symptoms associated with PMS (most typically irritability, tension, or unhappiness).
• Symptoms appear predictably during the luteal (premenstrual) phase, reduce or disappear predictably shortly before or during menstruation, and remain absent during the follicular (pre-ovulatory) phase of the menstrual cycle.
• The symptoms must be severe enough to disrupt or interfere with the woman's everyday life.

To establish a pattern, a woman's physician may ask her to keep a prospective record of her symptoms on a calendar for at least two menstrual cycles.^[6] This will help to establish if the symptoms are, indeed, limited to the premenstrual time and are predictably recurring. A number of standardized instruments have been developed to describe PMS, including the Calendar of Premenstrual syndrome Experiences (COPE), the Prospective Record of the Impact and Severity of Menstruation (PRISM), and the Visual Analogue Scales (VAS).^[1]

In addition, other conditions that may better explain symptoms must be excluded.^[1] A number of medical conditions are subject to exacerbation at menstruation, a process called menstrual magnification. These conditions may lead the patient to believe that she has PMS, when the underlying disorder may be some other problem, such as anemia, hypothyroidism, eating disorders and substance abuse.^[1] A key feature is that these conditions may also be present outside of the luteal phase. Conditions that can be magnified perimenstrually include depression or other affective disorders, migraine, seizure disorders, fatigue, irritable bowel syndrome, asthma, and allergies.^[1] Also, problems with other aspects of the female reproductive system must be excluded, including dysmenorrhea (pain during menses, rather than before it), endometriosis, perimenopause, and adverse effects produced by oral contraceptive pills.^[1]

Although there is no universal agreement about what qualifies as PMS, two definitions are commonly used in research programs:

• The National Institute of Mental Health research compares the intensity of symptoms from cycle days 5 to 10 to the six-day interval before the onset of menses.^[1] To qualify as PMS, symptom intensity must increase at least 30% in the six days before menstruation. Additionally, this pattern must be documented for at least two consecutive cycles.
• The definition formulated at the University of California at San Diego requires both affective (emotional) and somatic (physical) symptoms during the five days before menses in each of three consecutive cycles, and must not be present during the pre-ovulatory part of the cycle (days 4 through 13).^[1] For this definition, affective symptoms include symptoms like depression, angry outbursts, irritability, anxiety, confusion, and social withdrawal. Somatic symptoms include symptoms like breast tenderness, abdominal bloating, headache, and swelling of hands and feet.

The exact causes of PMS are not fully understood. While PMS is linked to the luteal phase, measurements of sex hormone levels are within normal levels. In twin studies, the concordance of PMS is twice as high in monozygotic twins as in dizygotic twins, suggesting the possibility of some genetic component.^[1][10] Current thinking suspects that central-nervous-system neurotransmitter interactions with sex hormones are affected.^[1] It is thought to be linked to activity of serotonin (a neurotransmitter) in the brain.^[4][11][12] Recent studies in rats indicate that levels of glutamate, an excitory neurotransmitter, spikes prior to menstration in the cortex and hippocampus. ^[13] High glutamate levels have been tied to mood disorders in several studies. ^[14]

Preliminary studies suggest that up to 40% of women with symptoms of PMS have a significant decline in their circulating serum levels of beta-endorphin. Beta endorphin is a naturally occurring opioid neurotransmitter which has an affinity for the same receptor that is accessed by heroin and other opiates. Some researchers have noted similarities in symptom presentation between PMS symptoms and opiate withdrawal symptoms.^[15]

In one study of 71 women with PMS, elevated levels of serum pseudocholinesterase were found. This enzyme is considered a possible marker for trait-anxiety.^[16]

A variety of evolutionary rationales for the syndrome have been offered, including that it is an epiphenomenon due to the selective advantage accruing to other phases of the hormonal cycle,^[17] that it leads to "intensification of male ardour during the next onset of fertility",^[18] and that it prompts females to reject infertile males (who cause PMS due to not impregnating the female). "... an infertile male/potentially fertile female partnership would tend to break down, thus allowing a new pair-bond to be formed. The greater the degree of premenstrual hostility of the female, the sooner a fertile mating could ensue."^[19] Any theory would have to account for the persistence of PMS over substantial evolutionary time, as it appears to afflict baboons as well.^[20]

Many researchers have also put forth the theory that PMS is caused primarily by cultural factors.^[21][22][23]