Lewy body diseases (LBDs) are brain disorders that cause problems with thinking and movement. These happen because of unusual protein build-up in the brain, forming Lewy bodies and neurites, leading to cell death. The two main types of LBDs are Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Many people with LBDs have trouble with thinking, called mild cognitive impairment (MCI), which affects their language and social skills. Current treatments help with movement issues but not language problems. This study is testing a new method called noninvasive brain stimulation (NIBS) that might help improve language skills without drugs or surgery. NIBS uses gentle electrical currents to change how the brain works.

• **Participants**: Right-handed, 60-80 years, with PD-MCI or MCI-LB.
• **Duration**: Will include home-based treatments.
• **Restrictions**: No pacemakers, metal in the body, or epilepsy.