Despite its catchall name, a headache is not uniform. It includes different types of pain—throbbing, pulsating, pounding, and has many causes, from stress and eye strain, to hormonal shifts, high blood pressure, and illness. The premenstrual headache, experts believe, is caused by hormones, and women with this of headache often describe having severe pain on one or both of the head that is accompanied by a host of other PMS symptoms, such as fatigue and joint pain. Headaches can be distinguished the kind of pain they produce:

• Tension: Feels like a tightening, pressing, or a band-like sensation around the back of the head or neck

• Migraine: Throbbing pain, usually on one side of the head; may include nausea and sensitivity to light

• Cluster:Usually felt on one side of the head, can feel like mild burning sensation; occurs in clusters, between one and four times a day, for periods that can last weeks or months

• Hormone:Severe pain on one or both sides of the head, during the luteal phase and accompanied by PMS symptoms, during ovulation and menses and accompanied by nausea, vomiting, and aura

• Rebound:Nonspecific, generalized pain similar to tension headaches, caused by overuse of medications

• Sinus: Pain and pressure around the eyes, cheeks, and forehead; upper teeth may ache.

• Secondary/Organic:Can cause pain, confusion, and visual disturbances, or appear to change in pattern. (This type headache is a symptom of another disorder or disease.)

Just because headaches are common doesn’t mean men and women always get the same kinds of headaches or get them in equal numbers.

For example, while nearly 80 percent of people experience a tension headache at some point in their lives, women are three times more likely than men to experience a migraine headache. In contrast, men are much more likely to get cluster headaches; 90 percent of people who get cluster headaches are male. In sheer numbers, however, migraine headaches are more prevalent; 29.5 million people get migraines, compared with the 1 million who get cluster headaches.

Headaches and Hormones

Headaches and hormones are related, but their connection entirely clear. Hormones, produced by the glands in the endocrine system, regulate a woman’s menstrual cycle and appear to many PMS symptoms. Whether hormones are directly responsible for headaches, however, is still up for debate.

On the one hand, some evidence suggests the hormone-headache connection is strong. Some women experience headache at specific times during their monthly cycles (at ovulation, the luteal phase, and during their periods). Women are more than men to get migraine headaches, and their migraines can during pregnancy (a time of massive hormone changes) may disappear or worsen after menopause (another time of hormonal change). On the other hand, some researchers that women who suffer from menstrual migraines (discussed in this chapter) are predisposed to migraines and the fact that get migraines during their period is actually more coincidental causative.

However, the interplay of progesterone and estrogen, and their effect on the brain chemical serotonin, does play a role in how the brain perceives pain.

Research has shown that hormones— in particular, progesterone and estrogen— appear to regulate the brain's ability to suppress pain. This may explain why women are more likely than men to have disorders in which chronic and severe pain is a major symptom (e.g., fibromyalgia). When estrogen levels are high, such as during ovulation, the brain releases more endorphins, which inhibit the pain signals received by the brain. But when estrogen levels are low, as they are in the luteal (or premenstrual) phase of the menstrual cycle, the brain seems to produce fewer endorphins, resulting in more intense pain.

Estrogen’s Effect on Pain

In 2002, researchers at the University of Michigan conducted a study that demonstrated the effects of estrogen on pain perception. Fourteen men and fourteen women were given harmless but painful jaw injections and were then asked to rate their pain on scale. Brain scans revealed that the women, who were in the early follicular phase of their cycles and had low estrogen levels, felt pain more intensely than the men. A subsequent study the following year looked at women in the early follicular phase, with low estrogen levels, and compared them while they wore an estrogen-releasing skin patch to mimic a later phase in their menstrual cycle when estrogen levels are higher. In the high estrogen phase, women reported their pain as less intense.

Serotonin

The neurotransmitter serotonin, which plays a big role in depression, is also thought to be the primary hormonal trigger for headaches. It appears to act as a filter for signals coming to the brain, screening out background or unwanted noise but admitting signals that demand attention. Studies have found that when serotonin levels are low, test subjects suffered headaches. But when they were injected with serotonin, the headaches disappeared. Estrogen increases production of serotonin and influences the way it binds to nerve cells.

Causes and Triggers

Although hormones play a big role in headaches, especially premenstrual headaches and migraines, muscle tension, constricted blood vessels, and inflammation also cause pain. For example, headaches are caused by the tightening or tensing of facial neck muscles (and sometimes by chemical or neurological while cluster headaches, migraines, and fever headaches are caused by constricting blood vessels. Infections, strokes, diseases can cause what are known as “inflammatory headaches” (sometimes referred to as organic or secondary headaches). Typically, these headaches are just a symptom of the underlying disorder.

The National Institute of Neurological Disorders and divides headaches into four categories, according to their causes:

• Vascular:Caused by constricted blood vessels; examples include migraine, fever headache (also known as toxic and cluster headaches

• Muscular:Caused by muscle contraction; a prime example the tension headache

• Traction: Caused by traction on intracranial structures; examples include pain produced by tumors, abscesses, or swelling

• Inflammatory: Caused by inflammation; examples include pain caused by sinus infection or meningitis

Headache Triggers

Stress, allergies, odors, medications, hormones, and certain foods are just some of the things that can trigger headaches— and interestingly, women are more vulnerable than men to all of them!

A 2002 study found that women who rely on over-the-counter pain relievers were anywhere from 4 percent to 17 percent more likely than men to get headaches triggered by stress, sinus allergies, foods, smells, spouses or children, and medications. The only thing men reported being more sensitive to was headache caused by cold beverages or ice cream. Twelve percent of men compared with percent of women reported “brain freeze” headaches.