JMIR Publications

ABSTRACT

Background:

The potential of the response times (RTs) to depressive symptom items as an implicit self-schema indicator for depression has yet to be determined via a mobile-based depression screening instrument, which was designed to readily record the experienced depressive symptoms on a daily basis. In this study, the well-validated Korean version of Center for Epidemiologic Studies Depression Scale-Revised (K-CESD-R) was adopted.

Objective:

The purpose of the present study was to investigate the relationship between depression severity (i.e., explicit measure: total K-CESD-R Mobile scores) and latent trait of interest in schematic self-referent processing of depressive symptom items (i.e., implicit measure: response times to the K-CESD-R Mobile scale), particularly in undergraduate students who had never been diagnosed with but were at risk for major depressive disorder (MDD) or comorbid MDD with other neurological or psychiatric disorders.

Methods:

Seventy participants (36 males and 34 females), aged from 19 to 29 years (mean 22.66, [standard deviation 2.11]), were asked to complete both mobile and standard K-CESD-R assessments via their own smartphones. The mobile K-CESD-R sessions (binary scale: yes or no) were administered on a daily basis for 2 weeks, and the standard K-CESD-R assessment (5-point scale) was administered once when delivered via a text message including a link of the survey directly to their mobile phones on the final day of the 2-week study period.

Results:

Five were excluded for a data analysis. The result of polynomial regression analysis showed that the relation between total K-CESD-R Mobile scores and the RTs to the depressive symptom items was better explained by a quadratic trend, F (2, 62) = 21.16, P < .001, R2 = .41, than by a linear trend, F (1, 63) = 25.43, P < .001, R2 = .29. It was further revealed that the K-CESD-R Mobile had excellent internal consistency (Cronbach’s α = .94), at least moderate concurrent validity with other depression scales such as the KQIDS-SR (r = .57, P < .001) and the PHQ-9 (r = .76, P < .001), and high adherence rate for all participants (65/70, 93 %) and follow-up rate for 10 participants whose mobile or standard K-CESD-R score was 13 or over (8/10, 80 %).

Conclusions:

As hypothesized based on a self-schema model for depression that represented both item and person characteristics, the inverted U-shaped relationship between the explicit and implicit self-schema measures for depression showed the potential of an organizational breakdown and a subsequent return to efficient processing of schema-consistent information along a continuum ranging from non-depression through mild depression to severe depression. It is, further, expected that the newly developed K-CESD-R Mobile app can play an important role in encouraging people at risk for depression to seek further mental healthcare professional follow-up.