A $400 test to evaluate your chances of bipolar disorder?

Claiming they can help evaluate a person's odds of having bipolar disorder, a California-based firm has just launched a new $400 genetic test. Does it work?

Harvard University researchers say it's unlikely. "When it comes to commercial genetic tests, we just don't know enough to make the tests useful," they report in the latest issue of the Harvard Mental Health Letter.

The saliva-based DNA test determines whether a person carries any of several different genetic variants that show up somewhat more often in people with bipolar disorder then they do in the general population.

In recent studies, for example, one such variant reportedly shows up in 1 percent of the population at large but 3 percent of people with bipolar disorder. That means most bipolar people don't carry the higher risk version of that gene. And most people with risk-associated genes don't develop the disorder.

The Harvard scientists warn against this and other similar tests coming on the market for schizophrenia and major depression. The latest research shows these disorders stem from a combination of different genetic risk factors and environmental triggers.

"Someday it may be possible to reliably assess risk for psychiatric disorders," wrote Michael Miller, editor of the Harvard Mental Health Letter. "But at this point, the technology - and the science - is still evolving."