On Thursday--National Depression Screening Day--sites will be set up across the United States offering free evaluations. (Call  262-4444 for the closest site.)
Once thought to be a psychological dysfunction, depression is now considered a serious and chronic brain illness influenced by genetic, biochemical, psychological and environmental factors.
Other depression facts:
* Each year, about 17 million Americans of all ages, socioeconomic classes, races and cultures suffer from episodes of the biologically based brain disease.
* Depression's economic toll in America is $43.7 billion a year.
* Despite its seriousness, depression is often trivialized and ignored.
* Depression is different from normal feelings of sadness after disappointments and acute grief after loss.
* Although "true" clinical depression and "normal" depression share many symptoms, the key difference is that clinical depression affects the entire system.
* Symptoms of clinical depression include persistent low and anxious feelings, fatigue, loss of interest in usual activities, sleep disturbances, appetite and weight changes, thoughts of death, impaired concentration and decision-making, and chronic aches and body symptoms not caused by physical disease.
* If several such symptoms drag on for more than two weeks, the sufferer should be evaluated for depression.
* Good news: More than 80% of all serious depressions can be alleviated with some combination of antidepressant medication and talk therapy. Bad news: Few seek help.
* Although a genetic propensity can amplify environmental factors, depression is often triggered by chronic stress. Still, most of the time specific stressors can't be identified as causal and many depressions occur spontaneously. This makes sufferers feel guilty for not having a "good enough reason" to feel so bad.
* If an episode goes untreated, it will eventually go away by itself. But 15% of untreated or inappropriately treated people will die first by suicide.
* SOURCES: National Alliance for the Mentally Ill, National Institute of Mental Health, American Psychiatric Assn., American Suicide Federation.