Modulating Prospective Memory in Older Adults With Non-invasive Brain Stimulation

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This study aims to modulate neural activity in the left and right inferior frontal lobe as well as in the right superior parietal lobe via high-definition transcranial direct current stimulation (HD-tDCS) in older adults. There is evidence from functional magnetic resonance imaging (fMRI) studies th...

This study aims to modulate neural activity in the left and right inferior frontal lobe as well as in the right superior parietal lobe via high-definition transcranial direct current stimulation (HD-tDCS) in older adults. There is evidence from functional magnetic resonance imaging (fMRI) studies that these areas are involved in prospective memory performance in younger and older adults but a causal relation between activity in these areas and responses in prospective memory tasks has not been established so far. A double blind, sham-controlled, parallel group design will be applied. Healthy older adults (n=105) will participate in two separate sessions: During the first baseline session, no stimulation is applied. For the second session, participants will then be randomly assigned to one of seven experimental groups (cathodal vs. anodal right inferior frontal lobe (rIFL); cathodal vs. anodal left inferior frontal lobe (lIFL); cathodal vs. anodal right superior parietal lobe (rSPL); or sham). Real stimulation will be applied during 20 minutes with one Milliamp (mA). In case of sham stimulation (i.e., control intervention), the electrode positions and the attachment procedures correspond to those of real tDCS but the electrical current will only be ramped up to one mA and switched off completely after 30 s of stimulation. The primary objective of this study is the modulation of prospective memory performance in a computer-based task via tDCS. Further, this study aims to clarify the role of attentional control for prospective memory performance, as both processes seem to recruit similar neural structures. Additionally, naturalistic and self-rated prospective memory performance will be assessed. It is hypothesized that stimulation of the right inferior frontal lobe will lead to changes in prospective memory performance and attentional processes. Whether cathodal or anodal stimulation will enhance performance is not clear yet, since previous fMRI studies were inconsistent about activity changes in older adults. Further, the investigators expect that anodal stimulation of the left inferior frontal cortex may lead to faster responses to prospective memory stimuli, whereas cathodal stimulation of the same area may lead to prolonged reaction times. It is hypothesized that attentional control will not be affected by stimulation of the left inferior frontal lobe. Finally, the investigators expect that anodal stimulation of the right superior parietal cortex will lead to better prospective memory and attentional control performance, whereas cathodal stimulation will have detrimental effects on both functions.

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