Research also shows that there are significant variations in the ways medications are absorbed by people of different races and cultures.

At the symposium "Overprescribing of psychoactive medication--evidence and remedies," Wendy Stock, PhD, of the California School of Professional psychology Alameda­Alliant University, offered examples of the discrepancies. For one, she presented data showing that African-Americans and Asians tend to metabolize SSRIs differently than whites, and may be getting too much of the medications as a result.

In addition, said Stock, foods commonly eaten by certain ethnic groups may also undermine a medication's effectiveness. For example, corn and charbroiled beef, popular among Hispanic cultures, interfere with how a drug affects the body.

When it comes to prescribing medications, said Stock, the rule is "start low and go slow."