Davidson, P. S. R. | Search bioRxiv

bioRxiv2019

Few Effects of a 5-week Computerized Cognitive Training Program in Healthy Older Adults

Computerized cognitive training programs are becoming increasingly popular and practical for cognitive aging. Nevertheless, basic questions remain about the benefits of such programs, and about the degree to which participant expectations might influence training and transfer. Here we examined a commercial cognitive training program (Activate) in a 5-week double-blind, pseudo-randomized placebo-controlled trial. Based on a priori power analysis, we recruited 99 healthy older adults 59-91 years of age (M = 68.87, SD = 6.31; 69 women), assigning them to either the intervention or an active control program (Sudoku and n-back working memory exercises). We subdivided both groups into high and low expectation priming conditions, to probe for effects of participants expectations on training and transfer. We assessed transfer using a battery of standard neuropsychological and psychosocial measures that had been agreed to by the training program developers. We planned and pre-registered our analyses (on osf.io). The majority (88%) of participants progressed through the training, and most provided positive feedback about it. Similarly, the majority (80%) of participants believed they were truly training their brains. Yet, transfer of training was minimal. Also minimal were any effects of expectations on training and transfer, although participants who received high expectation priming tended to engage more with their assigned program overall. Our findings suggest limited benefits of Activate training on cognition and psychosocial wellbeing in healthy older adults, at least under the conditions we used.

clinical trials↗

bioRxiv2018

Expectations may Influence the Effects of Transcranial Direct-Current Stimulation

Growing interest surrounds transcranial direct current stimulation (tDCS) as a safe and inexpensive method for improving cognitive functions and mood. Nevertheless, tDCS studies rarely examine psychological factors such as expectations of outcomes, which may influence tDCS responsiveness through placebo-like effects. Here we sought to evaluate the potential influence of expectations on tDCS intervention outcomes. We assessed expectations of tDCS outcomes in 88 healthy young adults on three occasions: i) at baseline; ii) after reading information implying either high or low effectiveness of stimulation; and iii) after a single-session of sham-controlled anodal tDCS applied to the left dorsolateral prefrontal cortex, during working memory (WM) training. Participants were largely uncertain about the effectiveness of stimulation in improving cognitive function at baseline. High or low expectation priming using simple positive or cautionary messages significantly increased or decreased expectation ratings, respectively, but ratings significantly decreased following stimulation in all groups. We found greater improvement in participants who received high compared to low expectation priming. Participants who received active stimulation and low expectation priming exhibited the lowest performance, suggesting that expectation priming and stimulation may have interacted. We did not find a significant effect of baseline expectations, belief of group assignment, or individual characteristics on measures of WM and verbal fluency. However, controlling for baseline expectations revealed greater post-intervention improvement on the executive function measures in participants who received high (compared to low) expectation priming. People randomly assigned to receive high expectation priming reported having a more pleasant experience overall, including greater satisfaction. Our findings suggest that expectations of outcomes should be taken into account in tDCS-based experimental studies and clinical trials.\n\nHighlights- Based on prior knowledge, healthy subjects are uncertain about NIBS effectiveness.\n\n- Expectations of NIBS can change after a single exposure to simple written messages.\n\n- Expectations of outcomes may influence cognitive performance.\n\n- High expectations may lead to a more positive experience and motivation to perform.\n\n- Low expectations may be counterproductive to NIBS.

neuroscience↗