The purpose of this research study is to determine the effectiveness of Transcranial direct current stimulation (tDCS) therapy in the treatment of participants with Late-life depression (LLD).

The study will evaluate feasibility, safety, and tolerability of high-dose (6mA) bilateral tDCS delivered as three daily sessions, 3 times a week, for 3 weeks in older adults (60 y/o and older) with late-life depression.

Inclusion Criteria:

Participants must meet all of the following criteria:

1. age 60 years or older;
2. diagnosis of unipolar major depressive disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), confirmed by the Mini International Neuropsychiatric Interview (MINI);
3. score of 17 or higher on the 17-item Hamilton Depression Rating Scale (HDRS-17) at screening;
4. stable antidepressant regimen for at least four weeks prior to enrollment, if applicable;
5. capacity to provide informed consent;
6. Clinical Dementia Rating scale of 0 or 0.5.

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded:

1. contraindications to tDCS including metallic cranial implants, skin conditions at electrode sites (eczema, open wounds, burns, lesions), or history of adverse reaction to tDCS;
2. contraindications to magnetic resonance imaging (MRI) including pacemaker, cochlear implants, ferromagnetic implants, or claustrophobia;
3. history of seizures or epilepsy;
4. bipolar disorder, psychotic disorders, or severe personality disorder;
5. dementia or MoCA score below 17;
6. substance use disorder within the past six months;
7. neuromodulation treatment including electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), tDCS, or vagus nerve stimulation (VNS) within the past six months;
8. active suicidal ideation with plan or intent requiring a higher level of care;
9. concurrent use of medications that substantially lower seizure threshold;
10. pregnancy.