Intensity-dependence of auditory-evoked potentials might present an early surrogate marker for post-stroke depression.

Objective: Post-stroke depression (PSD) is a common stroke complication, associated with severe physical and cognitive impairment. Low central serotonergic tone, associated with depression, inversely correlates with the intensity-dependence of auditory-evoked potentials (IDAP). Aim of this study was to investigate IDAP's usability as early surrogate marker for PSD development by assessing the correlation between IDAP early after stroke and the occurrence of PSD from 4 weeks after stroke.
Methods: We assessed auditory-evoked potentials (AEP) and depressive symptoms using the Montgomery-Åsberg Depression Rating Scale (MADRS) at day 1 - 3 and > 30 after stroke onset. IDAP was calculated as the linear slope of the N1-P2 amplitude/stimulus intensity function (ASF).
Results: 37 patients completed the study. We diagnosed 7 patients with PSD, defined as MADRS-score≥ 7 at follow-up. The PSD group showed significantly steeper ASF slopes at admission compared with the non-depressed group (p = 0.007). We also found a positive correlation between ASF slopes on first and MADRS-scores on last measurement point for all stroke patients as a group (p = 0.007).
Conclusions: The study findings support the hypothesis that IDAP can predict the development of depressive symptoms following stroke and may therefore serve as an early surrogate marker for PSD.
Significance: This is the first longitudinal study to assess the relationship between IDAP and PSD.
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