Synergistic effects of cognitive training and high-definition transcranial direct current stimulation across the dementia spectrum

We will use data from a 2x2 double-blind, randomized controlled trial in those with amnestic mild cognitive impairment (aMCI; n107) to evaluate the cognitive and physiological effects of high-definition transcranial direct current stimulation (HD-tDCS) when paired with either mnemonic strategy training or an autobiographical recall control condition.Participants completed five consecutive daily sessions (20 minutes/session) with either active (2 mA) or sham HD-tDCS targeting the left ventrolateral prefrontal cortex.Overall, active HD-tDCS resulted in robust neurophysiological effects using both univariate and functional connectivity during associative memory encoding when compared with sham.The combination of strategy training and active HD-tDCS yielded the largest effects that primarily involved frontoparietal regions and networks involved in topdown processing/control.A significant but anatomically distinct pattern of changes was evident in the autobiographical control + active HD-tDCS.Importantly, these effects suggest a relatively persistent benefit since outcome was measured 3-4 days after the last stimulation session.The combined results support the concept of functional targeting (i.e., engaging targeted brain regions/networks via task while delivering stimulation) by showing the effects of active HD-tDCS depend on the task performed during stimulation.Ongoing analyses evaluate 1) doseresponse relationships using finite element modeling, 2) the long-term persistence of these changes, as measured during a 3 month follow-up session, and 3) far-transfer effects using an n-back working memory task.