Sham stimulation will be applied to the left prefrontal cortex over the F3 electrode.

EEG P300 amplitudes time-locked to the incongruent trials of the Eriksen Flanker Task were assessed approximately 4-weeks after baseline. EEG event-related potential amplitudes (measured in microvolts, µV) were normalized across EEG channels using a scaling procedure, in which each channel was rescaled to reduce variability in signal magnitude among electrodes while preserving temporal and spectral characteristics. While larger P300 amplitudes are typically associated with better cognitive outcomes, this can vary among study populations.

Performance on the NIH Toolbox Dimensional Change Card Sort Test, a computerized measure of executive function assessing cognitive flexibility, attention, and set-shifting. Participants match target stimuli based on changing rules (e.g., color or shape). Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better cognitive flexibility and executive control.

Performance on the NIH Toolbox List Sorting Working Memory Test, which assesses working memory capacity through sequencing and recall of visually and verbally presented stimuli in size order. The task requires temporary storage and manipulation of information across increasing list lengths. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better working memory performance.

Performance on the NIH Toolbox List Sorting Working Memory Test, which assesses working memory capacity through sequencing and recall of visually and verbally presented stimuli in size order. The task requires temporary storage and manipulation of information across increasing list lengths. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better working memory performance.

Performance on the NIH Toolbox Picture Sequence Memory Test, a measure of episodic memory in which participants reproduce the order of a sequence of visually presented pictures. The task assesses the ability to encode, store, and retrieve sequential information. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better episodic memory function.

Performance on the NIH Toolbox Picture Sequence Memory Test, a measure of episodic memory in which participants reproduce the order of a sequence of visually presented pictures. The task assesses the ability to encode, store, and retrieve sequential information. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better episodic memory function.

Total of all reporting groups

Performance during the incongruent trials of the Eriksen Flanker Task were assessed approximately approximately 4-weeks after baseline. The performance is quantified as the ratio of correct responses to all responses. For example, a score of 0.70 indicates that the participant responded to 70% of the trials correctly.

Data for this outcome were missing at either baseline or posttreatment time points for 3 participants.

Reaction time during the incongruent trials of the Eriksen Flanker Task were assessed at baseline (before the beginning of the 4-week home tDCS intervention)

Data for this outcome were missing at either baseline or posttreatment time points for 3 participants.

Performance on the NIH Toolbox Dimensional Change Card Sort Test, a computerized measure of executive function assessing cognitive flexibility, attention, and set-shifting. Participants match target stimuli based on changing rules (e.g., color or shape). Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better cognitive flexibility and executive control.

Performance on the NIH Toolbox Dimensional Change Card Sort Test, a computerized measure of executive function assessing cognitive flexibility, attention, and set-shifting. Participants match target stimuli based on changing rules (e.g., color or shape). Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better cognitive flexibility and executive control.

Performance on the NIH Toolbox List Sorting Working Memory Test, which assesses working memory capacity through sequencing and recall of visually and verbally presented stimuli in size order. The task requires temporary storage and manipulation of information across increasing list lengths. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better working memory performance.

Reaction time during the incongruent trials of the Eriksen Flanker Task were assessed approximately 4-weeks after baseline.

Data for this outcome were missing at either baseline or posttreatment time points for 3 participants.

EEG P300 amplitudes time-locked to the incongruent trials of the Eriksen Flanker Task were assessed at baseline (before the beginning of the 4-week home tDCS intervention). EEG event-related potential amplitudes (measured in microvolts, µV) were normalized across EEG channels using a scaling procedure, in which each channel was rescaled to reduce variability in signal magnitude among electrodes while preserving temporal and spectral characteristics. While larger P300 amplitudes are typically associated with better cognitive outcomes, this can vary among study populations.

Data for this outcome were missing at either baseline or posttreatment time points for 4 participants.

EEG P300 amplitudes time-locked to the incongruent trials of the Eriksen Flanker Task were assessed approximately 4-weeks after baseline. EEG event-related potential amplitudes (measured in microvolts, µV) were normalized across EEG channels using a scaling procedure, in which each channel was rescaled to reduce variability in signal magnitude among electrodes while preserving temporal and spectral characteristics. While larger P300 amplitudes are typically associated with better cognitive outcomes, this can vary among study populations.

Data for this outcome were missing at either baseline or posttreatment time points for 4 participants.

Performance on the NIH Toolbox List Sorting Working Memory Test, which assesses working memory capacity through sequencing and recall of visually and verbally presented stimuli in size order. The task requires temporary storage and manipulation of information across increasing list lengths. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better working memory performance.

Performance on the NIH Toolbox Picture Sequence Memory Test, a measure of episodic memory in which participants reproduce the order of a sequence of visually presented pictures. The task assesses the ability to encode, store, and retrieve sequential information. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better episodic memory function.

Performance on the NIH Toolbox Picture Sequence Memory Test, a measure of episodic memory in which participants reproduce the order of a sequence of visually presented pictures. The task assesses the ability to encode, store, and retrieve sequential information. Scores are reported as fully corrected (for age, gender, race/ethnicity, and education) T-scores (mean = 50, SD = 10), with higher scores indicating better episodic memory function.

This group will receive daily sham stimulation to the left dorsolateral prefrontal cortex for 4 weeks through a home-based tDCS device in remotely-supervised 30-min sessions.

Adverse event was assessed by having participants complete a brief questionnaire on the presence and severity of possible adverse events after each at-home tDCS session. Events at moderate severity and above meet the criteria for "adverse event".

Adverse event was assessed by having participants complete a brief questionnaire on the presence and severity of possible adverse events after each at-home tDCS session. Events at moderate severity and above meet the criteria for "adverse event".

Adverse event was assessed by having participants complete a brief questionnaire on the presence and severity of possible adverse events after each at-home tDCS session. Events at moderate severity and above meet the criteria for "adverse event".

Adverse event was assessed by having participants complete a brief questionnaire on the presence and severity of possible adverse events after each at-home tDCS session. Events at moderate severity and above meet the criteria for "adverse event".

Adverse event was assessed by having participants complete a brief questionnaire on the presence and severity of possible adverse events after each at-home tDCS session. Events at moderate severity and above meet the criteria for "adverse event".