Cognitive training in young and old adults Transfer, long-term effects, and predictors of gain

Abstract: Aging, also in the absence of pathological conditions, is associated with cognitivedecline, especially in so called fluid abilities, such as episodic memory andexecutive functions. Due to an ongoing demographic shift, a larger part of thepopulation will reach higher ages, and more people will be affected by age-relatedcognitive decline. Finding ways of counteracting this development have the potentialof having large benefits for both individuals and society. It has long beenknown that living in environments that are rich in terms of cognitive challengescan affect cognitive ability in old age. In this regard, intervention studies in whichthe amount of cognitive stimulation is manipulated can therefore generate insightsto the causality of such effects in specific cognitive functions. Cognitive trainingas means to counteract negative effects of aging on cognition has received a lot ofscientific interest in the last decades.This focus of this thesis is cognitive training interventions, which is studiedfrom several perspectives. In Study i, the aim was to investigate the extent towhich executive functions can be strengthened by training in younger and olderadults, and to which degree such training generalize to other measures of cognition.Although a large body of research has been investigating training of workingmemory and executive functions in recent years, the results are diverse, and fewhave been targeting executive functions broadly with training programs based ontheoretical models of executive functions. Study i showed that despite a broadtraining program targeting three executive functions (updating, shifting and inhibition),it did not lead to transfer beyond the very near in old adults. The youngerhowever showed transfer effects to measures of working memory.In Study ii, the focus was on studying how the effects survive across time.There is limited knowledge about long-term effects of process-based training andthe results showed that the training effect was stable after 1.5 years, while only thenearest transfer effect was still significant in both younger and older adults.Study iii focused on individual factors affecting gain and maintenance thereofin a sample of older individuals. We used a strategy-based intervention focusingon episodic memory performance with a number-consonant mnemonic which is amnemonic for memorizing digit-codes. A different set of predictors was observedfor baseline episodic memory performance and training gain. Those that are betteroff in terms of episodic memory performance, also gain more in the episodic memorycriterion task. Further, a higher rate of processing speed was also important.Lastly, better verbal knowledge also influence gain beyond the other factors. Theresults have both theoretical implications regarding how plastic cognitive functionsare, and practical, in terms of how to best design training programs.