In the olden days of psychopharmacology — the 1950s through the 1980s — most prescriptions for antidepressants were written by psychiatrists. Now, Valley Mental Health psychiatrist Dr. Michael Measom says, "the vast majority of depression is treated by family-care doctors."

Many of those family physicians prescribe SSRIs (selective serotonin re-uptake inhibitors), drugs with familiar names like Prozac, Paxil and Zoloft. They are comfortable prescribing SSRIs because unlike the older classes of antidepressants — tricyclics like Elavil and MAO (monoamine oxidase) inhibitors like Nardil — the newer ones have fewer side effects and are hard to overdose on unless taken with other lethal drugs.

Dr. Measom defends the use of antidepressants — "it's a disorder of one of the organs of the body, the organ you use to relate to the world" — and notes a combination of antidepressants and psychotherapy have proven the best treatment. A study published earlier this week in the Journal of the American Medical Association, for example, concluded that a combination of Prozac and talk therapy works best for children and teens suffering from depression.

To warrant treatment with antidepressants, Measom says, a patient should meet the criteria for major depressive disorder, with symptoms — for at least two weeks — that include changes in sleep and appetite, decreased sex drive, problems with concentration and suicidal thoughts. Physical symptoms for which there is no clear cause may also be a sign of depression, Measom says.

But not all depression looks alike, not all antidepressants work the same, and not all bodies react the same way to the drugs. "If you pick any single SSRI and tried it on a random group of 100 patients with clear-cut depression," University of Utah School of Medicine psychiatry professor Dr. David Tomb says, "you would find significant improvement in about 60 percent, and a more modest improvement in another 15 percent."

The trick is to figure out a Plan B if a patient doesn't respond to the drugs or develops untenable side effects.

"You have a plethora of genes involved in giving us what we call depression, and that will reflect altered levels of a number of different neurotransmitters," Tomb explains. People with depression related to levels of serotonin, for example, are more likely to respond to depression with anger and irritability, he says. "They're more likely to tear your head off than cry." Patients whose depression is related more to the neurotransmitter norepinephrine, on the other hand, are more likely to have no appetite and "stare out the window thinking grim thoughts."