In this study, published in JMIR Mental Health, dr. George Aalbers and colleagues retrieved data from 217 individuals in the NESDA study to explore the potential of using smartphone-tracked behavioural markers to support diagnostics and improve recognition of these disorders.

Digital phenotyping
After obtaining informed consent and measuring participants’ depression and anxiety symptoms, the researchers installed Behapp, a “digital phenotyping” app, on the participants’s smartphones. Behapp continuously logs GPS location and timestamps of app usage (without recording content). From these data, we calculated behavioural metrics such as time spent at home, frequency of moving between locations, nighttime smartphone use, and frequency of social media and communication app usage. Our aim was to determine whether these behavioural metrics could help identify depression and anxiety symptoms, similar to how a blood test reveals physical health issues. We used a machine learning algorithm to discover which metrics were most informative and evaluated how well these could distinguish individuals with symptoms from those without.

Analysis
The analysis revealed that only one metric—how often a person moves between different locations—was potentially useful. Participants with depression or anxiety symptoms tended to move less frequently. Using this single metric, we were able to detect symptoms only slightly better than chance. Overall, our findings suggest that while GPS-derived behavioural data may offer some support for the timely recognition of depression and anxiety symptoms, the information provided by these metrics alone is limited, and additional data sources or methods are likely needed for more accurate detection.

Conclusion
These results align with previous work demonstrating that GPS data contains information about a persons’ mental health, supporting follow-up work. In clinical practice, GPS data might support symptom recognition when combined with other information sources. These findings could suggest encouraging or enabling persons to move more between locations might have salubrious effects.