Smartphone language and resting-state EEG indicators of self-focused attention prospectively predict major depressive...

Central to major depressive disorder (MDD) onset and maintenance is maladaptive self-focused attention, which can be reliably indexed by greater: (a) usage of first-person singular pronouns (e.g., I) in natural language and (b) alpha oscillations in resting-state EEG. Integrating these largely parallel bodies of research, the present study sought to explicate the associations between, and prospective predictive utility of, linguistic and neural indicators of self-focused attention in adolescents with remitted MDD over 12 months.

At baseline, 126 adolescents (ages 13-18) with (n = 66) and without (n = 60) remitted MDD completed resting-state EEG. Retrospective interviews determined the occurrence of major depressive episodes (MDEs) during the follow-up period. A total of ~2.3 million messages were passively acquired from adolescents' smartphones, on which the proportion of first-person singular pronouns was derived.

During the 12 months, 29 (23.0%) participants developed an MDE (28 remitted MDD, 1 control). Cox regression showed that while greater usage of first-person singular pronouns prior to MDE increased the risk for MDE (hazard ratio [HR] = 2.02, p < .001), greater resting-state alpha power at baseline decreased the risk for MDE (HR = 0.78, p = .001). Moreover, greater alpha power predicted subsequent first-person singular pronoun usage (β = 0.17, p = .004). Mediation analysis indicated a marginal suppression effect (bootstrapped indirect effect p < .10), such that accounting for first-person singular pronoun usage amplified the association between alpha power and MDE risk.

Findings highlight functionally distinct alpha mechanisms and provide support for smartphone-based first-person singular pronoun usage as a neurobehavioral risk factor and a potentially promising intervention target for adolescent MDD.