Smartphones can detect depression

Your smartphone may tell if you are depressed by tracking the number of minutes you spend using the device and your daily geographical locations, according to a new study.
Researchers from the Northwestern University found that the more time you spend using your phone, the more likely you are to be depressed.
The average daily usage for depressed individuals was about 68 minutes, while for non-depressed individuals it was about 17 minutes.
Spending most of your time at home and most of your time in fewer locations - as measured by Global Positioning System (GPS) tracking - also are linked to depression.

Having a less regular day-to-day schedule, leaving your house and going to work at different times each day, for example, also is linked to depression.
Researchers analysed the GPS locations and phone usage for 28 individuals (20 females and eight males, average age of 29) over two weeks. The sensor tracked GPS locations every five minutes.

Based on the phone sensor data, Northwestern scientists could identify people with depressive symptoms with 87 per cent accuracy.
"The significance of this is we can detect if a person has depressive symptoms and the severity of those symptoms without asking them any questions," said senior author David Mohr, director of the Center for Behavioral Intervention Technologies at Northwestern University Feinberg School of Medicine.

"We now have an objective measure of behaviour related to depression. And we're detecting it passively. Phones can provide data unobtrusively and with no effort on the part of the user," Mohr said.
The smartphone data was more reliable in detecting depression than daily questions participants answered about how sad they were feeling on a scale of 1 to 10.
Their answers may be rote and often are not reliable, said lead author Sohrob Saeb, a postdoctoral fellow and computer scientist in preventive medicine at Feinberg.
"The data showing depressed people tended not to go many places reflects the loss of motivation seen in depression," said Mohr.

"When people are depressed, they tend to withdraw and don't have the motivation or energy to go out and do things," Mohr said.
While the phone usage data didn't identify how people were using their phones, Mohr suspects people who spent the most time on them were surfing the web or playing games, rather than talking to friends.
"People are likely, when on their phones, to avoid thinking about things that are troubling, painful feelings or difficult relationships. It's an avoidance behaviour we see in depression," Mohr said.