Effects of Transcranial Stimulation on Memory for Social Information in Younger and Older Adults

Episodic memory decline is a normal and expected part of the aging process. However, not all types of memory show equal decline throughout the lifespan. Older adults experience deficits in the ability to remember associations between items over and above the ability to remember the items themselves (Spencer & Raz, 1995). In this study, I tested a novel technique to improve associative memory in older adults, transcranial direct current stimulation (tDCS). Stimulation was applied while participants studied face-name pairs, and participants then completed both cued recall and recognition tests. In addition to testing the beneficial effects of tDCS, several other parameters were tested. This included the generalizability of tDCS to other populations (i.e., younger adults), the difference in magnitude of tDCS effects depending upon the number of trial repetitions during encoding, and whether the effects would last after a delay. Results indicated that stimulation was effective in improving face-name associative memory performance, but only for younger adults. Multiple presentations of stimuli during a stimulated encoding session did not have an effect on tDCS impact. Effects of tDCS did persist 24 hours later in the younger adult sample, but this effect did not go above and beyond the effects on memory measured on the first day, suggesting that this result was simply a carry-over effect from enhanced performance on the first day. Taken together, results indicate that tDCS changes behavioral performance in certain populations, and that effects persist after a short delay.