This small mechanistic pilot study was ended prior to first enrollment after considering factors related to feasibility (e.g., available time and resources).

Behavioral adaptation is particularly relevant to anxiety and related disorders, where exposure-based therapies rely on such adaptation as part of behavior therapy.. However, while initial fear reactions generalize easily across contexts, subsequent adaption of behavior through learning is context-specific. The primary goal of this study is to investigate whether transcranial direct current stimulation (tDCS) can be used to acutely impact generalization of subsequent learning across contexts in an experimental paradigm. As part of this study, participants will complete a clinical interview and questionnaires, as well as a computer task asking them to make choices between stimuli on the screen and during which they may or may not receive tDCS.

Inclusion Criteria:

1. Primary diagnosis of an anxiety or related disorder, (defined as panic disorder, social anxiety disorder, generalized anxiety disorder, obsessive-compulsive disorder, and/or post-traumatic stress disorder);
2. aged 18-55;
3. ability to speak, read, write, and understand English sufficiently well to complete study procedures and provide informed consent;
4. Stable psychiatric medication use for at least 6 weeks.

Exclusion Criteria:

1. Lifetime history of psychotic symptoms or bipolar disorder,
2. Current substance use disorder;
3. Acute suicidality or homicidality,
4. Significant neurological disorder,
5. Any problems that would interfere with study participation, significant or unstable medical disorders and tDCS-related contraindications (e.g., implanted metallic substances, pregnancy, holes in the skull, skin abnormalities under stimulation sites).