Could a headset at home lift mood in Alzheimer's? new study aims to find out.

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Ability of subject to understand and the willingness to sign a written informed consent document. 2. Individuals who are 60 years or older. 3. Diagnosis of possible or probable AD according to the National Institute of Aging - Alzheimer's Association diagnostic criteria; individuals with mild cognitive impairment (MCI) due to AD, as defined by these criteria, are eligible if biomarker evidence supports the underlying AD pathology (e.g., amyloid or tau positivity in CSF or PET imaging). 4. In the determination of the PI in consultation with the delegated physician(s) patient's signs/symptoms are consistent with: a Clinical Dementia Rating (CDR) of 0.5 (MCI) with biomarker evidence of AD; or a Clinical Dementia Rating score of 1-2 (mild to moderate dementia). 5. Clinically meaningful AS of ADRD is defined by the presence of any affective symptom (i.e., depression, elation, anxiety, irritability, and apathy) and a total severity score on the NPI-Q ≥10. 6. Have an eligible caregiver willing to be present during stimulation sessions and answer questionnaires (see criteria below). 7. Can speak and read in English. 8. Stable doses of medications for at least one month. 9. Access to a reliable broadband internet connection. Caregiver 1. An adult who serves as an unpaid caregiver for an individual enrolled in the study as interpreted by the PI or delegate physician. 2. Adequate cognitive capacity to provide verbal consent to participate in the caregiver arm of the study. 3. Adequate reading, writing, hearing and verbal capacity to provide collateral information about the study participant, answer questions related to their health and care, and assist in tDCS sessions, Exclusion Criteria: 1. Unstable medical conditions (e.g. unstable angina, uncontrolled diabetes and hypertension, advanced cancer, etc.) that, in the opinion of the PI in consultation with delegated physician(s) would contraindicate study participation for safety or data quality reasons. 2. Medical history of serious psychiatric disorders (i.e. bipolar disorder, schizophrenia, manic depression etc.). 3. History of epilepsy. 4. Metallic objects in the brain, skull, or otherwise placed where it could interfere with DCS. 5. Have risk of suicidal behavior, defined as any suicidal behavior or suicidal ideation of type 4 (active suicidal ideation with some intent to act, without specific plan) or type 5 (active suicidal ideation with specific plan and intent) based on the Columbia-Suicide Severity Rating Scale (C-SSRS) in the 3 months prior to screening; 6. Unwillingness to undergo MRI at baseline and during the Week 2 conversion period for reasons other than a confirmed medical contraindication such as having a pacemaker or other implanted medal making MRI unsafe. 7. Being an active participant in other therapeutic clinical trial. Caregiver 1\. Any individual who does not meet all the inclusion criteria