While Google the company -- now known as Alphabet -- has spun its health operations into several growing subsidiaries, Google the search engine continues to be one of the major ways people seek to learn about their health. To its credit, Google has displayed an awareness of the "ask Dr. Google" phenomenon and over the years has steadily improved what people see when they make health-related search queries. Most recently, they partnered with Mayo Clinic and Harvard Medical School to provide high-quality health information.

Now the search giant is turning its attention toward depression, working with the National Alliance on Mental Illness (NAMI) to direct people who search for clinical depression on mobile devices to a clinically-validated screening test (the PHQ-9) that can help them evaluate whether they might have the disease. 

"Clinical depression is a very common condition — in fact, approximately one in five Americans experience an episode in their lifetime," Mary Giliberti, CEO of NAMI, wrote in a blog post for Google. "However, despite its prevalence, only about 50 percent of people who suffer from depression actually receive treatment. To help raise awareness of this condition, we’ve teamed up with Google to help provide more direct access to tools and information to people who may be suffering."

Providing any kind of screening tool online can be a difficult tightrope for companies that want to provide a service to casual information seekers without claiming to be a diagnostic tool, especially since false negatives present such a danger. But Google and NAMI are skirting that risk both by making the nature of the tool as clear as possible upfront and by using an existing evidence-based and clinically-validated tool.

"The results of the PHQ-9 can help you have a more informed conversation with your doctor," Gilberti wrote. "...Statistics show that those who have symptoms of depression experience an average of a 6- to 8-year delay in getting treatment after the onset of symptoms. We believe that awareness of depression can help empower and educate you, enabling quicker access to treatment. And while this tool can help, it’s important to note that PHQ-9 is not meant to act as a singular tool for diagnosis."

When a user searches for "depression," a button labeled "Check if you're clinically depressed" will appear within the existing Knowledge Graph card. Pressing that button takes the user to the questionnaire (and an assurance that the data won't be stored). Based on the results, Google will offer a score on a scale of zero to 27, along with an interpretation of that score and advice on how to proceed. Severe scores include a direct link to the National Suicide Prevention Lifeline.