tDCS Intervention in Breast Cancer Survivors With and Without Obesity Reporting Cognitive Impairment

This study is testing transcranial direct current stimulation (tDCS) — a non-invasive brain stimulation technique using mild electrical current applied to the scalp — to help breast cancer survivors who experience thinking and memory difficulties (often called 'chemo brain'). The study also looks at whether obesity affects outcomes. **You may be eligible if...** - You are a woman over 18 years old - You have been diagnosed with breast cancer (first diagnosis, adult-onset) within the last 5 years - You completed all active cancer treatments at least 3 months ago - You are fluent in Finnish or English - You are right-handed - You have normal or corrected vision and hearing - You have internet access **You may NOT be eligible if...** - You received cancer treatment (chemo, radiation, surgery, immunotherapy) within the past 3 months - You have a history of childhood cancer - You have dementia, Alzheimer's disease, multiple sclerosis, or Parkinson's disease - You have had a stroke or mini-stroke - You have metal implants (pacemaker, neurostimulator, cochlear implant, metallic eye implants) - You are pregnant or breastfeeding Talk to your doctor to see if this trial is right for you.