Cognitive Enhancement in Depression (The COG-D Study)

Non-invasive Neuromodulation to Enhance Targeted Cognitive Remediation in Older Adults With Depression

This study will investigate whether transcranial direct current stimulation (tDCS) enhances the effects of computerized cognitive training in older adults with recurrent depression (2 or more lifetime episodes; either current or within past 3 years).

The purpose of this study is to determine whether the addition of active tDCS to computerized cognitive remediation (nCCR) enhances brain activity and cognitive functions in older adults with recurrent depression to a greater degree than nCCR with sham stimulation. The investigators will randomize 20 elderly depressed outpatients to either double-blinded active or sham bifrontal tDCS plus daily nCCR over 4-weeks. Multimodal MRI (focused on the cognitive control network; CCN) and psychiatric and neuropsychological evaluations will be obtained at baseline and following intervention completion. Long-term CCN cognitive effects will be explored 3-months post-intervention via cognitive assessments.

Inclusion Criteria:

• Age 60+ years
• Diagnosis of a current or past (within last 3 years) depressive episode (e.g., Major Depressive Disorder (MDD), Persistent Depressive Disorder (PDD)) using Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria
• In total, participants must have 2 or more lifetime depressive episodes to be considered "recurrent"
• Either stable antidepressant regimen for at least 6 weeks or no current antidepressant treatment
• Evidence of subjective cognitive complaints on the Everyday Cognition Scale (ECog)
• English fluency

Exclusion criteria:

• Other Axis I psychiatric conditions via the DSM-5, except for anxiety symptoms occurring in a depressive episode
• Acute suicidality on clinical evaluation
• Acute grief
• History of alcohol use disorder or substance use disorder in last 12 months
• Currently taking medications that would significantly interact with tDCS effects (such as sodium channel blockers or anticonvulsants)
• Neurological disorders (e.g., dementia, stroke, seizures, traumatic brain injury, Parkinson's disease)
• Montreal Cognitive Assessment (MoCA) score < 23
• Primary amnestic cognitive profile (>1.5 standard deviations (SDs) below demographically-adjusted mean on National Alzheimer's Coordinating Center (NACC) memory measures in context of otherwise normal cognitive profile)
• Any physical or intellectual disability affecting ability to complete assessments
• Unstable medical illness needing urgent treatment
• MRI contraindications
• Electroconvulsive therapy (ECT) or transcranial magnetic stimulation (TMS) in last 2 months
• Current involvement in psychotherapy
• Current involvement in other research studies (including but not limited to: neuromodulation [TMS or tDCS] or investigational drug studies)