Discussion
cognitive decline
This RCT assessed the efficacy of a computerized multidomain home-based intervention combining physical and cognitive exercises on the cognition of older adults. The ZAVEN global cognition score indicated a significant intervention × time interaction as the cognition of participants improved in the SFL intervention after training, unlike those in the active control condition. This finding is consistent with the FINGER study, which reported positive effects for a 2-year multidomain intervention on global cognition [The positive effect found here deviates from the results summarized by Whitfield et al.’s [Another important aspect here was to examine effects on pre-frail individuals, who demonstrated a better response to training, which could have increased our ability to detect an intervention effect. Indeed, we found that pre-frail individuals randomized to the SFL intervention improved their global cognition and processing speed scores after the intervention, unlike participants randomized to the active control condition and unlike robust participants enrolled in either intervention. Thus, the effect observed when examining the entire group seems to be largely driven by the pre-frail participants, who showed a stronger response to this multidomain intervention. The effect found on the speed composite score might suggest that the improvement in processing speed drove the improvement in the ZAVEN global cognition score. Note, however, that there were benefits from the intervention when looking at the data from the other cognitive domains, even though these were non-significant. Hence, future research should focus on determining the cognitive domains that benefit most from similar interventions. The observed difference between pre-frail and robust individuals is consistent with the reserve/compensation hypothesis, which posits that vulnerable individuals are more likely to benefit from interventions designed to compensate for their difficulties, weaknesses or disabilities [The study has limitations that should be acknowledged: First, participants for the Belgian site were recruited and tested during the COVID-19 pandemic. Although we observed a site effect, this was due to performance of the Belgian and Canadian sites, being lower than the Swiss site. Thus, there is no indication for an effect specific to the Belgian site and no evidence that it modified the intervention effect. Second, frail individuals were excluded from our sample because we focused on prevention, but it could be interesting to examine whether the program has a positive effect on cognition in frail older adults. The sample size was estimated based on the physical outcome. Two of the composite scores used, executive and global cognition, showed low internal consistency. This indicates that they may reflect more than one cognitive construct. This was expected for the global cognition but not for the executive composite score. While it is an important issue, we did not include data on transfer to real-world daily functioning as our focus here was on cognition. Finally, the use of a purely computer-based intervention requires older adults to be technologically literate, which means that our group was biased toward those with technological skills.In conclusion, we report positive effects of a multidomain remote intervention on cognition in older adults and propose that pre-frail older adults may benefit most from the program. One other important feature of the study was the use of a computerized program that allowed the intervention to be conducted entirely in the participantʼs home, which has rarely been done in past studies. Using a computerized remote approach has many benefits: It reaches a larger audience than face-to-face interventions, it is cost-effective in the long-term, it increases accessibility and flexibility, and it allows for personalization of the activities. The finding that more vulnerable older adults benefit most from an intervention to reduce cognitive decline provides support for public health interventions that encourage prevention strategies in older adults by specifically targeting a vulnerable population.