Transcranial Alternating Current Stimulation and Cognitive Training Enhanced Performance and Theta Activity in Adults With Cognitive Impairment

Age-related cognitive decline is rising due to longer life expectancy, necessitating new treatments as current drugs are ineffective and costly. Transcranial alternating current stimulation at the theta frequency (theta-tACS) has shown promise in enhancing cognitive function in both young and elderly adults, but its effectiveness in those with cognitive decline is not well-studied. This study involved 27 participants with subjective cognitive decline (SCD), mild cognitive impairment (MCI), and dementia, who underwent multiple sessions combining computerized cognitive training with theta-tACS to assess its efficacy. Participants were randomly assigned to either a real-tACS or sham-tACS group. Before and after treatment, they completed several cognitive tasks, and their behavioral and EEG data were collected. Only the real-tACS group improved in the oddball task and exhibited increased event-related EEG amplitude in the theta range. These findings suggest that theta-tACS can improve cognitive performance in individuals with cognitive decline at both behavioral and psychophysiological levels, supporting its potential for alleviating cognitive decline in elderly populations.