BOOK REVIEW / NONFICTION : A Woman’s Journey Toward Equilibrium : THE BEAST, A Reckoning With Depression <i> by Tracy Thompson</i> . Putnam $23.95, 288 pages

Write about what you know? Yes, indeed. After years of covering the courts for the Atlanta Constitution and the Washington Post, investigative reporter Tracy Thompson finally acknowledged that she was probably her own best story: a woman who at 40 had struggled against clinical depression since she was a teen-ager. Along the way, she received a sad education in what depression is and what medicine has to offer. This book is the chronicle of her journey toward equilibrium.

It is not an easy trip, in great part because a distinguishing characteristic of the disease is self-deception. For years Thompson did a good job of convincing herself that she was not ill--merely worthless, unattractive and lacking in talent. It took misadventures with several doctors, many drugs and an arrogant but oddly helpful lover before she conceded that there was something awfully wrong.

There were warnings in her personal history. Her father’s mother “simply went to bed and stayed there for a decade,” perhaps unable to recover from the death of a daughter and her husband’s subsequent desertion.

When Thompson was injured in a freak car accident, the scar above her eye seemed to her a brand. She would never be beautiful, she thought, never even be just like everybody else. She was marked as an outsider, and gradually she drifted into the dark place where the Beast lived.

She had what she considers her first full-fledged depression during her junior year in college, in 1976. The description is enough to make anyone who has ever had just a run-of-the-mill rough week feel exquisitely grateful for having gotten off easy: “I was afraid that something was about to happen. . . . Facts had no boundaries; they unfolded like paper accordions in my head, offering vistas of a catastrophic future. My parents were getting old; that meant someday they would get sick and die. I had made a C on my English paper; that meant I was stupid and would not get a decent job after college. I didn’t have a date for Saturday night; that meant I would be alone forever.”

But somehow--and this is perhaps as frightening as what she went through--Thompson managed to get by for years. She graduated and got a job, was nominated for a Pulitzer Prize, fell in love and planned to marry. Yet all the while, there were days when she could not recall a paragraph she had just read, when the slightest criticism only served to confirm what she knew was her essential worthlessness.

She might have chosen the back door out had her lover not gotten her into treatment. There was one clumsy overdose that could have ended in death had she not grabbed for the phone, and there were suicidal thoughts that fortunately did not crystallize into action. But Thompson is one of the lucky ones, properly medicated, properly respectful of the disease that almost did her in.

She refers to her obsessive note-taking, an attempt to make sense out of painful nonsense and the resource that allows her to recreate the past with such accuracy. But her discipline also yields the one flaw in the book. Once Thompson finds her philosophical center, she tends to pound at it, over and over: Mental illness is no different than a chronic physical ailment like diabetes, and our society makes matters worse by encouraging shame and secrecy.

I would like to have learned more about treatments, their side effects and long-term efficacy, and about her re-entry at the Post after having been hospitalized for her condition. And I would like more on what it was like to find Mr. Right. Thompson easily convinces the reader that she has earned the right to any crumb of happiness she can find; it would have been nice to get a fuller look at her newly balanced existence.