The Importance of Technology in the Combined Interventions of Cognitive Stimulation and Physical Activity in Cognitive Function in the Elderly: A Systematic Review

Background: Numerous studies have been developed in an attempt to understand which factors best predict improvements in cognitive function in the elderly such as exergaming. The aim of this study was to investigate and systematize literature on intervention programs that simultaneously include cognitive stimulation and physical activity, understand the importance of the use of new technology, including exergaming or computer programs, and understand their impact on cognitive function in older adults, giving indications about their contribution to healthy aging. Methods: A narrative approach was used for extraction and synthesis of the data. Relevant studies were identified from electronic databases such as PubMed, Scopus, Web of Science, and Academic Search Complete. Results: Thirty-two articles, involving 2815 participants, were identified. All selected studies were randomized controlled studies. The studies were published between 2011 and 2020. All studies included a combination of cognitive and physical interventions. Many of the studies used technology to administer the cognitive stimulation program. Conclusions: Most of the analyzed studies used exergaming in physical and cognitive interventions, demonstrating that this new form of intervention exerts lasting and stable benefits in cognition. However, we concluded that more studies are needed to compare interventions that use exergaming or computer programs with traditional interventions.


Introduction
Numerous researchers have attempted to understand which factors best predict improvements in cognitive functions in older adults.Some of these factors are diet, cognitive stimulation, physical activity, sleep quality, among others.Several studies have suggested a significant impact of these factors on general cognitive functioning, especially memory, executive functioning, learning, and attention.
In recent decades, there has been a growing interest in cognitive changes that occur in the aging population and how we can prevent them.
Aging is a continuous and complex process characterized by progressive physical and psychological changes [1].In the most developed countries, the proportion of older adults has increased significantly, as a result of the decrease in birth rates and the increase in average life expectancy [2].The increase in demographic aging implies new challenges for society, such as keeping older adults healthy, active, and participative for a longer period of time, as advocated by the World Health Organization [3].
When considering a prescription for healthy and successful aging, the vital role of cognitive stimulation and physical activity is remarkable.This highlights the importance of non-pharmacological interventions, related to changes in the population's lifestyle [4].In the last decade, issues associated with new technologies, especially exergaming, have gained prominence and they have been used in the development of non-invasive intervention techniques.

Physical Activity
Numerous benefits of physical exercise are recognized for the health and well-being of the general population.Regular physical activity promotes the improvement of physical and mental functions [5] and is associated with decreased risk of mortality, diabetes, cardiovascular problems, stroke, and breast and colon cancer [6].In addition, it promotes improvements in bone health, in reducing the risk of osteoporosis, in postural stability, and in increasing flexibility, promoting a decrease in the risk of falls, one of the main causes of mortality in the aging population [7].
Physical activity is also important when it comes to mental health, allowing the prevention of dementia, maintaining independence, improving quality of life [8], and is associated with improvements in the level of depression [9], stress, and anxiety [7].Physical activity can decrease the risk of dementia by 28% [10], reverse some of the unwanted effects of a sedentary lifestyle, and contribute to delay brain aging and degenerative pathologies, such as Alzheimer's disease [11], being fundamental in improving memory and learning [12].In addition, it allows the attenuation of the effects of aging at the brain level, being fundamental for good cognitive functioning [10,13,14].
High levels of physical activity are associated with increased brain activity [15], increasing the brain's ability to establish new connections.Thus, by allowing higher levels of oxygen to be pumped into the body, it has a very positive impact on brain activity.Physical activity improves neuroplasticity, changing the synaptic structure and function in various brain regions [16].Physical activity modifies trophic signaling factors and neuronal function and structure in key areas for cognition [17].

Cognitive Stimulation
These cognitive changes are different in each individual; in some cases, they occur suddenly and, in others, in a gradual way [18].Thus, the growing study of this phenomenon promotes the improvement of diagnostic techniques, capable of distinguishing between normative and pathological processes of aging, and of preventive intervention, capable of outlining the most effective methods for active and meaningful longevity.
The aging process brings losses at the cognitive and functional level [19].The cognitive abilities that show the greatest deficit in the context of a normative aging process are memory, visuospatial capacity, and information processing speed [20].According to Calatayud et al. (2018) [19], interventions aimed at exercising and stimulating cognitive abilities may contribute to a reduction in the negative effects of aging, delaying the appearance of deterioration of the various cognitive functions.
Cognitive stimulation refers to a set of methods and techniques that aim to optimize the performance of cognitive functions, through compensation strategies and cognitive reserve, in order to enhance neuroplasticity [19] and it is based on the general view that a lack of cognitive activity accelerates cognitive decline [21].Cognitive stimulation promotes "involvement in activities aimed at the general improvement of social and cognitive functioning, in order to compensate irremediable neurocognitive deficits and maintain the daily function preserved for as long as possible" [22] (p.406).

Physical Activity and Cognitive Stimulation Combined: The Role of Exergaming
Physical exercise alone may not be enough to delay cognitive decline in the aging.Research has suggested that combining physical exercise with cognitive stimulation may be a more successful strategy [17,23,24].Adcock et al. (2020) [16] suggested that we must think about physical and cognitive activity inseparably, since muscles and body movements are controlled by the central nervous system, while feedback from peripheral structures such as muscles and sensory organs influence brain activity.For the same authors, mild cognitive decline and dementia are associated with greater physical decline, compared to older adults with normal cognitive functioning.
Exergaming can be very useful in cognitive stimulation, favoring intervention tasks [25].According to some studies, the combination of physical activity and cognitive stimulation using exergaming seems to be an effective strategy in the long term.One of these strategies is the use of exergaming.Video game playing may have cognitive benefits and it is highly motivating and likely to promote exercise adherence [26].
Thus, this systematic literature review aimed to investigate and systematize the literature on intervention programs that combined cognitive stimulation and physical activity published in the last decade, giving indications about their efficacy and, additionally, to understand the importance of exergaming or computers programs in the intervention with the elderly.

Protocol and Registration
This work adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [27] statement guidelines and was registered on PROSPERO with the number CRD42021231687.

Literature Search Strategy and Study Selection
Articles in English published in electronic databases such as PubMed, Scopus, Web of Science, and Academic Search Complete, from first records to 27 July 2022, were reviewed.The following keywords were used: "cognitive stimulation", "physical activity", and "older adults".No restrictions on language or publication type were applied.Two of the authors independently conducted an initial screening of titles and abstracts and assessed full-text versions of potentially relevant articles.Disagreements were resolved by a third author.The electronic search was complemented by hand-searching the references of included papers and previous reviews.

Eligibility Criteria
Studies were eligible for final inclusion in the systematic review if they cumulatively met the following criteria: studies carried out with older adults and whose participants took part in physical and cognitive intervention programs simultaneously; interventions where cognitive functioning has been evaluated; studies with peer review; randomized controlled studies; and no restrictions on language or publication type were applied at the moment of the database search.In the present study, the following types of publication were excluded: letters to the editor; comments; editorials; systematic reviews; and meta-analyses studies.Finally, studies that did not investigate the effect of the combination of physical activity and cognitive stimulation on the cognition of the older adults were also excluded.

Data Extraction Process
At first, possible studies for inclusion in the systematic review were identified.An electronic data extraction form was used, using the Excel program.After removing the duplicates, the titles and abstracts of the studies were screened.In this way, the relevant studies were extracted, according to the pre-defined inclusion criteria.Studies that did not meet the inclusion criteria were removed.In this study, the extracted data were synthesized in a table, with the following information: authors, year, sample size, frequency of intervention, study design, existence and timing of follow-up, type of cognitive intervention, type of physical intervention, objectives, and main results.

Quality Assessment
The researchers assessed the risk of bias in individual studies using the revised Cochrane risk of bias tool for randomized trials (RBO2) [28].

Selection of Studies
As shown in Figure 1, a total of 11,096 studies were identified through electronic database searching and one additional article was identified by back citation.After removing 555 duplicate records, 10,542 studies were screened based upon title and abstract, but 10,426 did not meet the eligibility criteria.The full text was retrieved for 116 articles, of which 84 were excluded.
duplicates, the titles and abstracts of the studies were screened.In this way, the relevant studies were extracted, according to the pre-defined inclusion criteria.Studies that did not meet the inclusion criteria were removed.In this study, the extracted data were synthesized in a table, with the following information: authors, year, sample size, frequency of intervention, study design, existence and timing of follow-up, type of cognitive intervention, type of physical intervention, objectives, and main results.

Quality Assessment
The researchers assessed the risk of bias in individual studies using the revised Cochrane risk of bias tool for randomized trials (RBO2) [28].

Selection of Studies
As shown in Figure 1, a total of 11,096 studies were identified through electronic database searching and one additional article was identified by back citation.After removing 555 duplicate records, 10,542 studies were screened based upon title and abstract, but 10,426 did not meet the eligibility criteria.The full text was retrieved for 116 articles, of which 84 were excluded.Thirty-two studies were identified that combined physical activity and cognitive stimulation.Of the thirty-two analyzed, eighteen studies (56.3%) presented a low risk of bias.Five (15.6%) studies had a high risk of bias.Finally, nine studies (28.1%) had some concerns (Table 1).

Type of Participants
Most studies included people over the age of 60.Participants with mild cognitive impairment, with dementia, and who were cognitively healthy were included (Table 2).

Duration of the Interventions
Regarding the duration of the interventions, the studies varied between 7 weeks [53] and 40 weeks [54], with physical and cognitive training that varied between 10 and 110 min per session, which were divided by two to five days a week.

Intervention Groups
Several studies did not have a control group [23,36,37,40,41], and they compared the effectiveness of physical activity and cognitive stimulation with each of its components administered in isolation.All other studies compared the combination of physical activity and cognitive stimulation with the isolated administration of cognitive stimulation or a control group, in the cognitive functioning of the older people.

Assessment of Participants
Regarding the neuropsychological assessment tests used, most studies used the Mini Mental State Examination (MMSE) to screen the sample, and participants should fall within a range of scores.Only six studies did not use the MMSE as a cognitive screening test [16,23,36,40,46,49].In all studies, participants underwent an extensive battery of neuropsychological tests to assess various cognitive domains.

Type of Interventions
Studies were included if they focused on interventions simultaneously combining cognitive stimulation with physical activity in older adults.Cognitive stimulation was focused on several domains of cognitive functioning, for example, memory, attention, executive functions, spatial-temporal activities, language, and others.The intervention could include structured cognitive intervention programs [23,49].Physical exercises included any form of structured physical activity, such as aerobic exercise, strength or functional, toning, cycling, and walking.

Use of Technologies
Some of the studies in this review used exergaming or computer programs (43%).Exergaming interventions were included because the gaming activities combined physical activity with cognitive stimulation [22,35,38] (Table 2).The results suggested that the elderly who were submitted to cognitive stimulation had more benefits in terms of cognitive functioning.

Results of the Combination of Interventions on Cognitive Functioning
The analysis of the studies demonstrated that there was a significant impact of the combination of cognitive stimulation and physical activity on the cognitive functioning of elderly people with different cognitive performances.According to the analysis of the results, executive functioning is the cognitive function where the greatest impact of the combination of these two types of intervention is observed [16,30,35,56].
In inactive older adults with cognitive complaints, physical and mental activity was associated with significant improvements in global cognitive function [46] in the long term [40].It was more advantageous to administer cognitive training and physical activity simultaneously than isolated [33].

Discussion
The objectives of this systematic review of the literature were to systematize all recent studies on the combined interventions of physical activity and cognitive stimulation on the cognitive functioning of older adults, to understand the impact of the use of exergaming integrated in these interventions, and to obtain information about its effectiveness in contributing to healthy aging.
Many of the studies used technology to administer the cognitive stimulation program, namely exergaming or computer programs.Several studies suggest that the use of technology, namely computer programs, can be advantageous for the cognitive functioning of the older adults, namely in terms of memory [57].Exergame training seems to be a motivating and promising option for simultaneous physical-cognitive training in older adults [22].The use of these programs is expected to allow the prevention and treatment of cognitive decline, to decrease a sedentary lifestyle, cause a reduction in the time spent on the intervention, and cause a decrease in the necessary resources [23].This type of intervention seemed to be more effective in treating the elderly compared to traditional interventions.They can be used in cognitive stimulation and physical activity.Most of the studies used the exergaming technique, which consisted of activities that included physical activity and cognitive stimulation in an articulated way and simultaneously.One of the most well-known and publicized instruments is the Wii-Fit Pro, which has been widely used in intervention with the elderly.Exergame works as a new health strategy with the purpose of providing cognitive and functional improvement and/or maintenance in the elderly, promoting healthy aging.In fact, all analyzed studies using exergaming demonstrated significant results in improving cognitive functioning.However, the analyzed studies did not compare computerized interventions with traditional interventions, and it was not possible to deduce the difference in effectiveness between the two.
Independently of the use of technology to administer the intervention, most of the studies presented demonstrated that the combination of physical activity and cognitive stimulation is most beneficial for cognitive functioning in the aging population.
However, although this efficacy has been demonstrated, some studies revealed some differences and contradictions [36,44,48].In two studies [36,48], no significant advantages were found in the combination of physical activity with cognitive stimulation in the aging.In one study [44], inconsistent results were found.These differences can be explained by methodological differences.
Several studies did not have a control group, namely the studies [23,36,37,40,41], although all were randomized control trials.This is perhaps because these studies had the aim of identifying the additional benefit of adding a physical exercise intervention to a cognitive one.For this reason, they compared the results of combining the two interventions with a group that only received cognitive stimulation.For the authors, a control group was considered to be a group that did not benefit from any type of intervention.
Although several intervention programs used physical activity and cognitive stimulation, few investigations analyzed and compared the combination of both, with each of the components administered in isolation and with a control group [24,48,50].The remaining studies compared the combination of physical activity and cognitive stimulation with only one of the variables in isolation.However, the results were inconclusive [24], significant differences in psychomotor speed were found in the group that received aerobic and cognitive training (exergame) when compared to the control group.However, in same studies, there were no statistically significant differences, since, according to the authors, combined training did not produce synergistic effects [48,50].
In addition, the short-term effects of the interventions did not reveal significant differences in most of the analyzed cognitive functions.Although the discovery that the combination of cognitive stimulation and physical activity significantly improves psychomotor speed may be clinically relevant, as psychomotor speed is an important predictor of functional decline [24], more conclusive studies are needed regarding the effect of physical activity and cognitive stimulation on different cognitive functions.Some of these cognitive functions are less sensitive to the intervention of physical activity, with no significant changes in these cases, which is why studies in this regard remain fundamental [48].
Through the results obtained, it is possible to verify that thirteen studies were carried out with a sample with mild cognitive impairment or a formal diagnosis of dementia.These results suggest that there was some variety in the studies developed, with them not being focused only on a segment of the population.The fact that, in recent years, numerous studies have been carried out with cognitively healthy subjects is advantageous, since it allows the development of increasingly effective strategies to promote healthy aging.
Only eleven studies performed a follow-up after their interventions.This is a limitation that some authors identified [58] and that we agree with, since it does not allow drawing conclusions about the effectiveness of the combination of physical activity and long-term cognitive stimulation.Studies with follow-ups are sometimes inconclusive, not revealing any significant changes over the long term in most conditions analyzed [24].
Based on the analysis of the studies, it is possible to conclude that the factors that influence cognitive and physical dysfunction are susceptible to intervention.Thus, neuropsychological and physical interventions can be fundamental for normative aging, since they have the potential to delay the decline in cognitive and physical functions.Given the cognitive improvements, after the interventions, it is possible to infer that brain plasticity is present in the aging population and that cognitive decline can be delayed in cognitively healthy participants and individuals with mild cognitive impairment [23].

Limitations and Future Directions
Several key limitations of this comprehensive systematic review should be acknowledged.The characteristics of the studies included in the analysis varied widely, for example, in the focus of the intervention, in the objectives, in the number and time of the sessions, in the sample size, in the cognitive functions evaluated, and in the type of physical activity implemented.For this reason, meta-analysis or statistical comparisons were not possible.
Future studies should focus on the development of new technologies, applying them in their intervention programs, in an attempt to make them more effective; on the other hand, future studies should: compare the effectiveness of interventions that use exergaming with traditional interventions; use follow-up strategies to verify the effects of this type of intervention in the long term; understand the impact of the combination of the two forms of intervention on other personal individual variables (depression, anxiety, quality of life, psychological well-being and performance, daily living activities); compare the effects of the combination of physical activity and cognitive stimulation with each of its components administered separately; and, finally, future studies should try to distinguish the benefits of the combination of physical activity and cognitive stimulation according to the user's cognitive level (cognitively healthy, mild cognitive impairment, and dementia).
We also found that the various studies analyzed only addressed the effects of the intervention on cognition, not mentioning the positive impact that cognitive stimulation may have on the performance of activities of daily living for the elderly.Several studies have addressed the issue of the transfer effect, claiming that cognitive stimulation does not generalize beyond the specific tasks that are worked on [59].The concept of transfer consists in the generalization of the results obtained to other domains of cognition or to tasks that, in some way, differ from the target of the training program [59].Therefore, future studies should seek to understand the effect of the combination of cognitive stimulation and physical activity in the performance of daily living activities in the elderly.

Conclusions
As scientific research in the area of aging progresses, the results suggest that a healthy lifestyle, with regular practice of physical activity and constant investment in cognitive stimulation activity, is essential for a healthy and meaningful process of aging.It was more advantageous to administer cognitive training and physical activity simultaneously than alone [33].Combining physical exercise with cognitive stimulation is a more successful strategy [25].Both cognitive stimulation and physical training induce changes in the brain function and structure of healthy elderly people, namely in the functioning of the frontal lobe and in the increase in white matter in the frontal and parietal regions [58].
Despite not finding studies that compared the effectiveness of using traditional stimulation techniques with those using exergaming, these seem to have advantages compared to the rest [57].The use of new technology promotes, in addition to the significant improvement in cognition, the reduction in sedentary lifestyles, the reduction in time spent in the intervention, and the reduction in the necessary resources.
Recent studies indicate that cognitive activities are complex and challenging, mobilizing more than one cognitive domain simultaneously.In the coming decades, we must join efforts to associate new technologies with cognitive stimulation activities, in order to make our interventions increasingly effective.On the other hand, future studies could be carried out to assess the needs of the elderly, with regard to technologies, specifically in terms of motivators and barriers to their use.

Figure 1 .•Figure 1 .
Figure 1.Flowchart of the selection process of studies for inclusion in the systematic review.
Note.CCT = computerized cognitive training; CT = cognitive training; PA = physical activity; RCT = randomized control trial; AD = Alzheimer's disease; CTE = cognitive training combined with physical activity.

Table 1 .
Critical appraisal of the studies with randomized design included in the review, based on Cochrane risk of bias tool.

Table 2 .
Summary of studies involving physical activity and cognitive stimulation.