tDCS for Late-Life Depression

Inclusion criteria

Participants must meet all of the following criteria:

• age 60 years or older;
• diagnosis of unipolar major depressive disorder according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), confirmed by the Structured Clinical Interview for DSM-5 (SCID-5);
• score of 16 or higher on the Quick Inventory of Depressive Symptomology-Clinician Rated (QIDS-C) at screening;
• stable antidepressant regimen for at least four weeks prior to enrollment, if applicable;
• willingness and capacity to provide informed consent;
• Clinical Dementia Rating scale of 0 or 0.5.
• availability of an informant who has sufficient knowledge of the participant's daily functioning as ascertained by the study team.

Exclusion criteria

Participants meeting any of the following criteria will be excluded:

• contraindications to tDCS including metallic cranial implants, skin conditions at electrode sites (eczema, open wounds, burns, lesions), or history of adverse reaction to tDCS;
• contraindications to magnetic resonance imaging (MRI) including pacemaker, cochlear implants, ferromagnetic implants, or claustrophobia;
• depressive disorder due to a medical condition;
• psychotic depression;
• history of seizures or epilepsy;
• bipolar disorder;
• psychotic disorders;
• severe personality disorder;
• active substance use disorder within the past six months or history of substance induced mood or psychotic disorder;
• neuromodulation treatment including electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), tDCS, or vagus nerve stimulation (VNS) within the past six months;
• active suicidal ideation with plan or intent requiring a higher level of care;
• concurrent use of medications that substantially lower seizure threshold;
• pregnancy;
• a clinically established diagnosis of dementia as reported in the participant's health record or scoring 1 or above on CDR;
• medically unstable in the clinical opinion of the principal investigators.