Objective
This systematic review aims to assess the effects of transcranial electrical stimulation (tES) on adults with anxiety. It focuses on evaluating physiological markers like heart rate variability (HRV), electroencephalogram (EEG), cortisol, and Interleukin-6 (IL-6) levels alongside various rating scales.

Methods
The review process, adhering to PRISMA guidelines, involved a thorough literature search across databases such as Embase, Scopus, PsycINFO, PubMed, and Web of Science. The risk of bias and quality of studies was evaluated using the JADAD scale. In total, 34 articles were meticulously chosen and analyzed by independent reviewer pairs.

Results
The review included 34 studies, encompassing 1567 participants aged between 18 to 65. The findings were mixed: while 19 studies reported a reduction in anxiety symptoms, 10 found no significant differences, and 4 did not report changes in anxiety. Two studies were inconclusive.

Conclusions
The review highlights a lack of standardized protocols for using tDCS in treating anxiety. The methodological quality of most studies was critically low, per PRISMA guidelines. There was considerable variation in methodological approaches across the studies, indicating a need for standardization in the research of anxiety treatment using tES.