A couple excerpts on perimenopausal depression from The New York Times article The Estrogen Dilemma:

There’s no way for me to separate the effects of estrogen from the effects of the antidepressant, except that on the few occasions when I’ve been haphazard about replacing the estrogen patches on time, I’ve experienced prompt and unmistakable intimations of oncoming [depression]...

Some psychological surveys will tell you there’s no evidence for a surge of clinical depression at menopause. I believe that, given how many other phases of life can unhinge us, but I also believe — no, actually, I know — that there is a difficult thing that happens to some women in the perimenopausally affected brain. Hostile as I am to generalizations involving women rendered fragile by biology, here I am, and here, too, is Berry, both of us pulled out of something terrible by a pharmaceutical infusion of estrogen. Two physicians who specialize in hormones and mood, Louann Brizendine, a neuropsychiatrist at the University of California, San Francisco, and Claudio Soares, a Canadian research psychiatrist who works at McMaster University in Ontario, told me that women who seek them out tell variations of the same story Berry and I took to our doctors: I know that something is wrong with me because I also know, somewhere in the noncrazy part of myself, that there is such pleasure to be offered by the circumstances of my grown-up life.

“These women thought they were losing their minds,” Brizendine told me, describing the 40-to-60-year-old patients she began seeing when she opened the Women’s Mood and Hormone Clinic at the university in 1994. “In 1994 we didn’t have words for it,” she said. “Now we do. It’s called perimenopausal depression.”

Brizendine and Soares, like Schmidt and Rubinow, have found that various combinations work with varying degrees of effectiveness for many of us — hormones with an antidepressant, hormones without an antidepressant, sometimes antidepressants on their own. The alternatives-to-hormones recommendations are mostly fine things in their own right, varying from certainly useful to harmless: exercise regularly, keep the weight down, easy on the caffeine, calm yourself with deep breathing or yoga, try black cohosh. (You could start a bar brawl over the efficacy of black cohosh, but the general consensus seems to be: if it works for you, go for it.) But the troubles set off by ricocheting hormones are reliably fixed by making the hormones stop ricocheting. And the laborious weighing of hormones’ benefits versus hormones’ harms — maybe not at the crisis moment, for those of us at our most distraught, but later, one or two or five years down the road — is something still undertaken by millions of women along the full breadth of the perimenopausal spectrum...