FRIDAY, July 18 (HealthDay News) -- Scientists may have found more evidence that a person's genetic make-up may help determine whether or not they respond to the antidepressant Celexa (citalopram).

Specifically, researchers at the Mayo Clinic have found that variations in the serotonin transporter gene could help select which patients should try this drug, one of the family of medications known as selective serotonin reuptake inhibitors (SSRIs).

Some 10 percent of the American population now take antidepressants, making it the most widely prescribed drug class in the country.

But finding the right antidepressant can be a painful, trial-and-error approach, with physicians not knowing which drug is right for which patient until they've actually tried it.

"Patients want to feel better as quickly as possible, so the idea of trying one drug after another until you find one that works can be discouraging. The development of pharmacogenetic testing will help increase the likelihood of selecting an effective drug the first time," study senior author Dr. V. David Mrazek, chairman of the Mayo Clinic's department of psychiatry and psychology, said in a clinic news release. Mrazek is also director of the Clinic's Genomic Expression and Neuropsychiatric Evaluation (GENE) Unit.

Mrazek and his colleagues looked at the serotonin transporter gene, SLC6A4, in about 2,000 individuals.

White patients who had two variations of the gene were more likely to get help from Celexa. There appeared to be no link between the two variations and the odds of remission in black or Hispanic patients.

"The findings of this study represent another step in advancing individualized medicine for psychiatric patients," Mrazek said.

The study was published in the current issue of the American Journal of Medical Genetics Part B: Neuropsychiatric Genetics.

More information

The National Institute of Mental Health has more on depression.