Healthy cognitive aging through cognitive training, physical exercise, and leisure activities : from theory to new interventions

Abstract

Neurocognitive health is becoming increasingly important in our aging population. Worldwide, around 47 million people are living with dementia and the number is expected to increase to 131.5 million by 2050. Engagement in a cognitively and physically demanding lifestyle over the lifespan is associated with healthy cognitive aging and a reduced risk of dementia in observational studies. However, translation of these findings into cognitive and physical interventions that effectively induce broad cognitive benefits was limited so far.

Article 1 aimed to compare lifestyle- and intervention-related cognitive changes for the first time in the same sample and time period. Cognitive change was more positively associated with an active lifestyle than with traditional cognitive and physical training interventions, suggesting that the interventions did not fully implement the active ingredients (i.e., effective features) of an active lifestyle. Hence, theoretical, methodological, and empirical advances with respect to active ingredients are necessary for the development of more effective interventions. For this purpose, we proposed three theoretical frameworks that each derived one active ingredient: The overlapping variability framework suggested the combination of process-specific cognitive demands with high task variability as an effective feature (see Article 2); the guided plasticity facilitation framework proposed high temporal proximity of cognitive and physical demands as a decisive factor (see Articles 2 and 3); and the plasticity components framework assumed that the combination of process-specific cognitive demands with novel, educationally relevant information improves efficacy (see Article 4). In addition, we designed and assessed the effects of two intervention programs that implemented these frameworks: a card and board gaming intervention based on the overlapping variability framework (see Article 2) and a computerized, combined cognitive and physical training intervention based on the guided plasticity facilitation framework (see Article 3). We found evidence for broad cognitive benefits through both interventions in a pilot, randomized controlled trial (see Article 2) and in a large-scale, multi-center, controlled trial (see Article 3). In exploratory analyses of the combined cognitive and physical training intervention, we observed a trend for reduced cognitive benefits in participants with more severe neurocognitive disorders as well as a dose-response association between the number of training sessions and cognitive gains in individuals without dementia (see Article 3). To assess the plasticity components framework, Article 4 suggested that educational games are well suited for its implementation and proposed a research strategy to select and evaluate appropriate games.

Next to the need for advances in intervention efficacy, the cognitive demands and benefits of frequently performed - but so far scientifically unexplored - leisure activities need to be revealed. Closing this science-practice gap is relevant as on the basis of dose-responsive effects not only efficacy but also amount of practice determines an activity's potential for cognitive benefits. Article 5 and 6 assessed the potential of jigsaw puzzling for healthy cognitive aging as an example of a frequently performed but so far unexplored leisure activity. The results indicated that jigsaw puzzling recruits multiple visuospatial cognitive abilities, e.g., working and episodic memory, reasoning, and cognitive flexibility. Additionally, the findings indicated that jigsaw puzzle experience over the lifespan is a new modifiable protective factor of cognitive aging, even though causality has not been clarified so far. The study provided no evidence that a 30-day jigsaw puzzle intervention improved cognition in a clinically relevant way.

Finally, the neurobiological correlates of activity-related cognitive gains are relevant to pave the way for personalized treatments. However, knowledge in this area is still in its infancy, especially regarding the role of white matter integrity. Article 7 found no evidence that increases in white matter integrity is a neurobiological correlate of short-term activity-related cognitive changes in older adults at risk of dementia. However, a positive association between two training outcomes (cognitive training skill and functional physical fitness) and white matter integrity indicated a theoretical potential for training-related gains in white matter integrity.

Taken together, the findings of Article 1 indicated a need for advances in intervention efficacy as the active ingredients of lifestyle-related cognitive changes may not be fully implemented in traditional training interventions. In Articles 2-4, theoretical, methodological, and empirical advances were provided regarding intervention efficacy by proposing three theoretical frameworks, designing two new interventions, providing evidence for their efficacy regarding gains in broad cognitive abilities, and suggesting cost-efficient research strategies for the selection of potentially beneficial activities in future trials. To clarify the unexplored potential of many frequently performed leisure activities for healthy cognitive aging, Article 5 and 6 revealed cognitive demands and effects of jigsaw puzzling as one example of these activities. Finally, Article 7 shed light on the role of white matter integrity as a potential neurobiological correlate of activity-related cognitive changes.