Effects of Alpha Transcranial Alternating Current Stimulation on Stress Reactivity and Decision Making: A Randomized Sham-Controlled Trial

AI Summary

Prefrontal 10 Hz tACS significantly increased stress-induced salivary cortisol compared with sham (AUCg 103.4 vs 76.4; p = .048).
Alpha tACS reduced delay discounting after stress, indicating decreased impulsive choice relative to sham.
Findings imply modulation of prefrontal alpha weakens top-down regulatory control, linking frontal alpha to stress reactivity and decision making; potential therapeutic relevance.

AI Summary

In this study, we investigated whether alpha tACS (α-tACS), delivered to healthy individuals while they experienced an acute stress situation, would influence biological stress responses and DM performance. RESULTS: Compared with sham (mean area under the curve with respect to ground [AUCg] = 76.4, SD = 29.63), α-tACS (mean AUCg = 103.4, SD = 49.08) significantly increased stress-induced cortisol release (p =.048, Cohen's d = 0.342). α-tACS also significantly decreased discounting rates following stress whereas no effect was observed in the sham condition. These mechanisms offer promising therapeutic prospects for stress-related disorders like posttraumatic stress disorder, which involve altered alpha-band oscillations and blunted cortisol reactivity.

Basic summary

Biol Psychiatry Glob Open Sci. 2026 Apr 9;6(4):100731. doi: 10.1016/j.bpsgos.2026.100731. eCollection 2026 Jul.

ABSTRACT

BACKGROUND: Evidence suggests that alpha-band power plays a crucial role in stress response and decision making (DM). Transcranial alternating current stimulation (tACS) is a noninvasive brain stimulation technique capable of modulating brain oscillations in a frequency-specific manner. In this study, we investigated whether alpha tACS (α-tACS), delivered to healthy individuals while they experienced an acute stress situation, would influence biological stress responses and DM performance.

METHODS: In a double-blind, sham-controlled study, 38 healthy individuals were randomly assigned to receive either α-tACS (2 mA, 30 min, 10 Hz; n = 19) or sham stimulation (n = 19) on the prefrontal cortex (PFC) during stress exposure. Salivary cortisol reactivity was measured repeatedly to assess the biological stress response, DM was assessed with the delay discounting task.

RESULTS: Compared with sham (mean area under the curve with respect to ground [AUCg] = 76.4, SD = 29.63), α-tACS (mean AUCg = 103.4, SD = 49.08) significantly increased stress-induced cortisol release (p = .048, Cohen’s d = 0.342). α-tACS also significantly decreased discounting rates following stress whereas no effect was observed in the sham condition.

CONCLUSIONS: Although some limitations, such as the absence of electroencephalography recordings and high variability in outcomes should be considered, these findings suggest that modulation of prefrontal alpha oscillations via tACS may reduce top-down regulatory control from the PFC, resulting in an enhanced biological stress response. This effect was accompanied by alterations in DM processes, supporting a functional relationship between frontal alpha activity, stress reactivity, and DM. These mechanisms offer promising therapeutic prospects for stress-related disorders like posttraumatic stress disorder, which involve altered alpha-band oscillations and blunted cortisol reactivity.

PMID:42233088 | PMC:PMC13224353 | DOI:10.1016/j.bpsgos.2026.100731

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