Beyond Self-Report: Depressive Symptom Severity Tracks Rapid Neural Responses During Natural Reading of Clinically...

Individual differences in depression symptom severity are associated with negative self-relevant thoughts that can operate implicitly and increase vulnerability to major depressive disorder. However, most paradigms designed to probe such implicit processes rely on simplified stimuli and artificial self-relevant judgments. We asked whether neural activity measured during natural reading of clinically grounded, self-relevant depression symptom probes can capture implicit schema-based patterns of expectancy and evaluation grounded in individuals' depression-relevant thoughts and experiences.

We recorded event-related potentials as 39 participants with a range of subclinical depression symptoms, indexed by the Beck Depression Inventory (BDI), read 160 self-relevant probes targeting depression constructs drawn from clinical rating scales and the DSM-5. Participants also read matched non-self-relevant probes describing another person's depression-consistent or depression-inconsistent experiences.

Higher BDI scores predicted differences in neural responses to depression-consistent versus depression-inconsistent self-relevant critical words within the first second after word onset. Relative to depression-inconsistent words, depression-consistent self-relevant words elicited 1) smaller N400s (300-500 ms), indicating stronger expectations for depression-consistent information that facilitated early meaning access, and 2) larger late positive potentials (600-900 ms), indicating greater motivational salience and sustained evaluation. These effects were specific to self-relevant probes and were not explained by general differences in sensitivity to depression-related content or expectancy.

Subclinical depression symptom severity is reflected in time-resolved neural activity during comprehension, without overt responses on each trial. These findings link clinically relevant symptom variation to implicit neurocognitive mechanisms supporting real-time processing of self-relevant information.