Perimenopausal symptoms are mostly caused by changes in hormone levels, which don't simply decline during perimenopause, but rather rise and fall wildly, peaking, then dropping abruptly, and rising again. This is caused by the aging of the ovaries, which, after decades of regular hormonal cycles, produce less estrogen and progesterone in perimenopause. In response, the pituitary gland compensates increasing the amount of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) it secretes to stimulate follicles. The maturing follicles raise estrogen and progesterone levels again: they first produce estrogen, and then, after ovulation, progesterone. However, this is a short-term solution; over time, the pituitary gland has to produce more and more FSH and LH to keep the process going, until at last, estrogen and progesterone ultimately decline and you enter menopause. Women in menopause have high levels of FSH.

Compared with younger women, women in perimenopause:

• Have higher amounts of follicle-stimulating hormone (FSH levels start to rise about five years before menopause)

• Have higher levels of luteinizing hormone (which starts rise about one year before menopause)

• Have occasional high levels of estriadol (one type of estrogen), as FSH stimulates follicles

• Have gradually decreasing levels of estrogen and progesterone

Where Does Estrogen Fit In?

Research shows that estrogen levels can intensify the body's response to stress. In a 2004 study, Yale researcher Rebecca M. Shansky and her colleagues subjected rats to mild stress and then gave them a short memory test. Without stress, both male and female rats performed well on the tests and performed equally well after experiencinghigher levels of stress. However, mild stress affected the female rats more. Shansky found that the responses were associated with the animals' high estrogen phase and concluded that high levels of estrogen enhance the body's stress response and cause greater stress-related cognitive impairment.

What does this have to do with perimenopausal women? Plenty, some experts believe.

For one, while perimenopause is usually described as a time when estrogen decreases, some studies have found that estrogen levels are actually higher in perimenopausal women than in younger women. Second, perimenopausal women don't ovulate every menstrual cycle. This means that for perimenopausal women, estrogen levels increase in the first half of their menstrual cycle, but because they don't ovulate, the pituitary gland secretes FSH to stimulate another follicle, which makes high estrogen levels rise again about a week or so later. This peak in estrogen not only induces physical premenstrual symptoms like breast tenderness (especially in the front of the breast) and stretchy cervical mucus (which increases as estrogen levels rise and is associated with ovulation), but also induces stress-related symptoms.

Jerilynn C. Prior, M.D., a Canadian endocrinologist and director of the Center for Menstrual Cycle and Ovulation Research, argues that high estrogen levels coupled with intermittent ovulation (which is common in older women whose reproductive function is declining) explains why perimenopausal women have symptoms such as hot flashes and night sweats, changes in libido, and PMS symptoms.

Depression and Perimenopause

Depression accelerates perimenopause. A 2003 study in the journal Archives of General Psychiatry found that women with depression begin perimenopause earlier than women who are not depressed. Researchers followed 1,000 women ages thirty-six to forty-six for three years and found that those with a history of depression were more likely to display symptoms such as changes in their menstrual cycles and missing periods, or they had to begin hormone replacement therapy earlier to regulate their cycles and alleviate symptoms such as hot flashes and flushing. Experts speculate that depression may slow the production of hormones.

Poor women are also more likely to go through perimenopause and menopause earlier, research shows. A 2003 study published in the Journal of Epidemiology and Community Health found that women who experience lengthy periods of economic hardship became peri-menopausal sooner. Study author Lauren Wise speculates that stress, poor nutrition, or toxins such as lead and tobacco accelerate egg depletion, which is known to trigger perimenopause.

Are You Experiencing Perimenopause?

If you want to learn if you're in perimenopause, you may be tempted to buy an over-the-counter test that promises to tell you. However, these tests measure levels of FSH, which rise and fall over the course of the menstrual cycle, even in aging women. So while the test may be able to tell you that your FSH is elevated, it can't tell you that you're definitively in perimenopause.

Researchers have actually found that a woman's own self-assessment, not a separate “objective” test, was the most accurate way to determine perimenopause. In 2003, investigators from Duke University reviewed research from 1966 through 2001 and found that there was no one symptom or test to confirm or rule out perimeno-pause. The most accurate ways of determining this phase were, in descending order: a woman's own self-assessment, hot flashes, night sweats, vaginal dryness, high follicle-stimulating hormone levels, and low inhibin B levels (a chemical that suppresses FSH).

Perimenopause Treatments

Some treatments for perimenopause are similar to PMS treatments, while others are used to treat more menopause-like symptoms. They include the following:

• Low-dose oral contraceptives, which help regulate periods and may reduce hot flashes and sleep problems, as well as prevent unwanted pregnancy

• Antidepressants to help stabilize moods

• Progestin (sometimes called the minipill) to reduce irregular bleeding and for nursing mothers

• Estrogen creams, applied topically around the vaginal area, to reduce dryness

Lifestyle changes can also reduce symptoms and prevent health problems related to menopause:

• Exercise, especially strengthening exercises, help prevent muscle loss, while stretching exercises help you stay flexible.

• Add soy to your diet to reduce hot flashes and other symptoms. Soy contains isoflavones, which have estrogen-like properties.

• Calcium supplements help prevent bone loss.

• Alternative therapies such as yoga may help relieve emotional symptoms by reducing stress, as well as provide health benefits, such as increased fitness.

• Some herbal treatments such as evening primrose oil, black cohosh, and ginkgo biloba may be effective in relieving symptoms such as hot flashes, mood swings, and night sweats. But always use herbal products with caution and consult your physician before taking them.