JMIR Publications

ABSTRACT

Background:

The benefits of physical activity (PA) for both physical and mental health, including major depressive disorder (MDD), are well established. Mobile devices, such as smartphones, offer a scalable way to monitor PA and its relationship with depressive symptoms in daily life.

Objective:

This study aimed to investigate the association between passive smartphone-recorded step counts and current depressive symptoms in individuals with and without a lifetime diagnosis of MDD, using a naturalistic bring-your-own-device (BYOD) approach.

Methods:

We used the Remote Monitoring Application in Psychiatry (ReMAP) to collect passive step count data from participants’ personal smartphones. The sample included 181 individuals with a lifetime MDD diagnosis, assessed via the Structured Clinical Interview for DSM-IV (SCID), and 195 healthy controls (HC). Current depressive symptoms were assessed using the Beck Depression Inventory (BDI). Physical activity was operationalized as daily and weekly step counts, passively recorded via smartphone sensors. Hierarchical models were applied to examine the association between PA and depression severity.

Results:

Patients with MDD exhibited lower overall step counts and reduced diurnal variability compared to HC. Furthermore, higher step counts were associated with lower BDI scores in both groups. Analysis of weekly patterns additionally revealed that total weekly step counts significantly correlated with lower concurrent BDI scores.

Conclusions:

These findings underscore the potential of mobile devices as effective tools for monitoring physical activity in patients with MDD, supporting more customized and adaptive approaches to prevention and treatment. They also emphasize the importance of incorporating physical activity into the clinical management of depression.