Ridge’s test amplifies that signal by bunching several markers together. The company’s scientists screened more than 100 biomarkers to select the combination of 10 for its depression test. These markers are related to systems known to be affected in depression, specifically the metabolism, immune system, nervous system, and hormones produced by the hypothalamus, pituitary gland, and adrenal glands.
Ridge CEO Lonna Williams says the company has validated the biomarker panel and its algorithm through eight studies done on several hundred patient and control samples. To date, they have shown that the blood test results correlate with diagnoses made using the mental health gold standards—the DSM-IV criteria and the Hamilton Depression Rating Scale—almost 90 percent of the time.
Papakostas has led controlled studies of the blood test as a paid advisor to Ridge Diagnostics. “This test appears to be promising,” he says, but cautions that, “thus far, it’s been used as a research tool.” The next step, he says, is to apply the test on a larger scale and in the community to validate its usefulness as a screening tool.
“The benefit of this kind of screening tool is …to apply this where you don’t have anyone qualified to screen for depression,” Papakostas says, such as rural communities where mental health professionals are scarce, or in primary care offices, to see whether a patient needs a psychiatric referral.
Ridge has already begun marketing the test in a limited geographic area on the basis of existing results. Physicians in North Carolina and in Southern California, where the company has its lab and headquarters, can order the test now; the company chose these areas so its staff can work closely with doctors using the test.
Williams says that Ridge has also undertaken case studies to see whether its test can help doctors encourage people to seek psychiatric treatment and to stick to an antidepressant regimen. The company is also developing a blood test to monitor antidepressant therapy. The goal, Williams says, is to be able to discern in a week or two whether a patient is responding to a drug, rather than the four to six weeks it can take to see symptom improvement. “It’s very exciting to see the early data from those two studies, because it can make such a difference in the treatment of patients,” Williams says.