Cognitive stimulation

Cognitive stimulation has been extensively applied as an intervention to people with mild to moderate dementia and has been evidenced as a privileged methodology in this area (^{Aguirre et al., 2014}; ^{Capotosto et al., 2017}; ^{Piras et al., 2017}). In general, the literature defines cognitive stimulation as a non-pharmacological technique that precludes cognitive decline and comprises computer-based cognitive stimulation systems (e.g. computers and tablets) and other traditional approaches that do not include computerized training, with multiple group activities, including engaging in non-specific activities (^{Mendes et al., 2022}; ^{Woods et al., 2012}) such as mentally challenging exercises, museum visits, puzzles, and daily life activities.

Cognitive stimulation intervention is aimed at improving general cognition and social functioning (^{Bahar-Fuchs et al., 2013}; ^{Clare & Woods, 2004}; ^{Eckroth-Bucher & Siberski, 2009}; ^{Gates & Sachdev, 2014}; ^{Kim & Kim, 2014}; ^{Kueider et al., 2014}; ^{Melguizo Herrera et al., 2017}; ^{Miranda-Castillo et al., 2012}; ^{Mowszowski et al., 2010}; ^{Steinerman, 2010}) based on the social environment and multisensory stimulation (e.g., attention, language, problem-solving, memory, information processing speed), for example by increasing attention to improving orientation or engaging in activities to improve memory. This approach combines fun, learning, improving performance and skills, and enhancing social contacts (^{Piras et al., 2017}). Also, the literature highlights that cognitive stimulation may preserve or improve cognitive abilities besides reducing the decline caused by normal ageing.

Various studies reported cognitively stimulating activities or tasks (computerized and non-computerized) to reduce cognitive decline (^{Newson & Kemps, 2006}) and improve the cognitive functioning, health, quality of life, and well-being of healthy older adults (e.g. ^{Castel et al., 2017}; ^{Fernández-Prado et al., 2012}; ^{Tranter & Koutstaal, 2008}) or older adults with dementia (^{Toh et al., 2016}; ^{Woods et al., 2012}; ^{Yuill & Hollis, 2011}). Research also suggests that cognitive stimulation intervention increases global cognitive functioning within a period of 6 to 12 months among people with cognitive impairment of distinct causes (mild cognitive deficit and other statuses of dementia) (^{Lin et al., 2013}).

Cognitive stimulation without computerized tasks: a traditional intervention

Most studies (see Table 1) that do not include technology showed gains after cognitive stimulation in older adults with mild to moderate dementia (^{Capotosto et al., 2017}; ^{Spector et al., 2003}; ^{Woods et al., 2006}; ^{Yamanaka et al., 2013}; ^{Young et al., 2019}), older adults diagnosed with mild to moderate vascular dementia (VaD) (^{Piras et al., 2017}), and individuals with AD (^{Miranda-Castillo et al., 2012}; ^{Vidovich et al., 2011}).

The study by ^{Spector et al. (2003)} conducted a program consisting of 45-minute sessions twice a week over 7 weeks. The study included a prominent reality orientation approach and focused on cognitive stimulation of 201 older adults with dementia (including multisensory stimulation). Results indicated improvements in the individuals’ cognitive functioning and quality of life, namely in emotional symptoms. Along the same line, ^{Woods et al. (2006)} demonstrated that cognition-based interventions directly impacted the quality of life in older adults diagnosed with dementia.

Another study by ^{Spector et al. (2010)}, using the same theoretical concepts and a methodological approach similar to their previous study (^{Spector et al., 2003}), demonstrated improvements in conversation and communication and a positive impact on the well-being of 201 older adults with dementia. Despite their promising results, no significant changes in memory and orientation or praxis were found. ^{Yamanaka et al. (2013)} reached similar findings in a study with 56 older adults with dementia (26 in the treatment group and 30 in the control group) designed based on principles of the cognitive stimulation program (^{Spector et al., 2003}) adapted to the Japanese culture. Their results demonstrated significant benefits in improving the cognitive function, quality of life, and mood of participants with dementia. ^{Capotosto et al. (2017)} showed similar results, namely, decreased emotional loneliness, in 39 older adults with mild to moderate dementia.

^{Piras et al. (2017)} applied a cognitive stimulation intervention in a specific population of 35 older adults with mild to moderate vascular dementia (VaD) divided into two groups: the intervention group, composed of 21 individuals who attended the 14 sessions of the cognitive stimulation program, and the other group, which took part in alternative educational activities. They analysed the cognitive functioning, quality of life, mood, behaviour, and functional activities of daily living and detected improvements in general cognitive functioning and a trend toward increased short-term/working memory in the intervention group.

Contrary to most studies, some did not evidence positive effects on the quality of life of older adults with dementia who integrated a cognitive stimulation program without technology. Namely, ^{Young et al. (2019)} and ^{Young (2020)} applied an expanded traditional cognitive stimulation model (without computerized tasks) with tai chi techniques to older adults with mild-stage dementia and found a trend toward improving general cognitive functioning but no overall increase in quality of life. ^{Stewart et al. (2017)}, who applied a cognitive stimulation intervention to 40 older adults with dementia, also did not detect differences in quality of life, even though encouraging results were highlighted in cognitive functioning and reduced depression levels.

Regarding AD, in particular, three studies used traditional interventions. ^{Niu et al. (2010)} integrated 32 older adults with mild to moderate AD in a cognitive stimulation therapy group that included individual tasks using executive functioning and working memory, such as "The reality orientation task," "The fluency task," "The overlapping figure task," and "The photo-story learning task." The training consisted of 45-minute sessions twice a week for 10 weeks, and positive effects were found, with decreased apathy and depression symptomatology. ^{Miranda-Castillo et al. (2012)}, who integrated 22 participants diagnosed with AD in a program of 14 sessions of cognitive stimulation therapy, found improvements in cognitive function and quality of life in the intervention group but no differences in functional ability in either group.

^{Vidovich et al. (2011)} applied a 12-week cognitive activity program with a follow-up of 6 months post-intervention to 128 older adults with AD divided into two groups. In group 1, individuals with mild AD and their companions participated together in a 7-week intervention of one 90-minute session per week focused on cognitive abilities usually affected in AD (attention, processing speed, memory, language, and executive functions). The program had a supervision and practice component with strategy techniques and examples of home activities, with phone-call support. In turn, group 2 only included carers, who received information and materials in the same terms as Group 1 and were instructed to transmit all the knowledge to facilitate patients in their natural environment and everyday situations. The main results revealed an improvement in quality of life and decreased cognitive decline in older adults with mild AD. That study also suggests that the cognitive stimulation approach for individuals with AD is probably more reliable when caregivers are also included in therapy.

Cognitive stimulation intervention without computerized tasks has also been shown to be beneficial for people with MCI. In a two-stage study, ^{Moro et al. (2012)} applied cognitive stimulation to 30 older adults with MCI divided into two groups. Both groups were assessed at an early stage of the program, but only 15 individuals of group A took part in an immediate cognitive stimulation intervention for six months. Group B only attended the program in the second stage and received specific training for six months. Positive effects of cognitive stimulation were detected in memory, particularly in short-term and working memory for group A and long-term memory for group B. These results are encouraging and emphasise the significant role of specific training in reducing cognitive impairments in people with cognitive decline. Similar findings were found later by ^{Moro et al. (2015)} in a sample of 30 older adults with MCI participating in a program based on cognitive stimulation, whose main intervention focused on general cognitive functions, executive functions, memory, and language. In addition to improvements in memory, the authors found an increment in performance and general functions.

^{Dannhauser et al. (2014)} conducted a study combining physical activity with cognitive stimulation to test a complex multimodal activity intervention (ThinkingFit program) in reducing the risk of dementia in 67 older adults with MCI. The intervention had three components: physical activity and group and individual cognitive stimulation training (in domains of attention, processing speed, working memory, problem-solving, and reasoning). The results showed positive outcomes for physical health and fitness and improved working memory. Previously, ^{Thiel et al. (2012)} had already concluded that physical activity, together with cognitive stimulation intervention, could prevent age-related cognitive decline in a large sample of seniors.

A study by ^{Alves et al. (2014)} with a sample of 20 older adults with cognitive impairment (cognitive decline ranging from MCI to mild-to-moderate dementia) used two distinct approaches – a standard cognitive stimulation program (17 sessions, six weeks) and a brief cognitive stimulation program (11 sessions, four weeks) — to assess changes in different domains: neuropsychological, functionality, quality of life, and caregiver outcomes. Findings pointed out outstanding adherence and completion rates, acceptable costs, and high values of experiential relevance to users. Despite these conclusions, the remaining results were not considered clinically significant.

Many studies have confirmed the benefits of cognitive stimulation intervention in healthy older adults. In the study by ^{Castel et al. (2017)}, 176 older adults were divided into two groups: 123 participated in a cognitive stimulation program, while 53 formed a control group, using a pre-and post-test design. Participants engaged in various tasks related to orientation, memory, language, gnosis, praxis, reminiscences, numerical calculation, attention, and concentration, without the use of computerised methods. Results showed an improvement in psychological well-being in the cognitive stimulation group. ^{Tranter and Koutstaal (2008)} observed gains in cognitive functions, such as problem-solving and flexible thinking, in n study that encouraged engagement in mentally stimulating activities. ^{Zimmermann et al. (2014)} applied two different approaches for direct and indirect stimulation of working memory: the first group attended a structured working memory training program with 2-hour sessions for 6 weeks, while the second integrated a poetry-based stimulation program of twelve 2-hour sessions for 6 weeks. Both interventions showed benefits in executive functions (direct stimulation) and linguistic abilities (indirect stimulation). ^{De Oliveira et al. (2014)} also demonstrated positive effects on executive functions and linguistic abilities in a population of healthy older adults, applying a multisensory and cognitive stimulation method.

Other studies with healthy older adults have found similar benefits when applying traditional cognitive stimulation interventions, including positive results in executive function, memory, and attention (^{Suzuki et al., 2014}), general cognitive functionality (^{Fernández-Prado et al., 2012}; ^{Melguizo Herrera et al., 2017}; ^{van Zon et al., 2016}); memory and verbal fluency (^{van Zon et al., 2016}); and memory span, updating and memory self-perception and processing speed (^{Grimaud et al., 2017}).

Cognitive stimulation using computer-based assistive technology

Studies on cognitive stimulation based on computerized tasks and supported by technological methodologies have shown strong evidence suggesting that cognitive stimulation intervention in a particular domain improves performance in that specific domain for individuals with mild to moderate cognitive impairment.

^{Djabelkhir et al. (2017)} applied computerized cognitive exercises and social interaction activities in a sample of 19 patients with MCI divided into two groups of intervention: computerized cognitive stimulation (first group, 9 participants) and computerized cognitive engagement (second group, 10 participants). The first group was involved in computerized cognitive exercises (KODRO software) and social interactions, and results confirmed improvement of inhibitory control, mental flexibility, and self-esteem, as well as a higher performance in free recall. The second group conducted tasks previously defined (e.g., exploring applications about a specific theme) in an informal context. Although the main results showed positive effects in processing speed, episodic memory, and self-esteem, no significant differences were detected in quality of life, memory complaints, anxiety, and depression between computerized cognitive stimulation and computerized cognitive engagement. These results are corroborated by another study that confirms this software enables the improvement of executive functioning, processing speed, and memory (^{Djabelkhir-Jemmi et al., 2018}). The study by ^{Malvy (2016)} also documented the positive effects of the KODRO cognitive stimulation program applied to 11 individuals diagnosed with MCI, particularly in four domains of six cognitive functions tested: memory, attention, language, and praxis. Participants used a touch tablet in a weekly session for 12 months.

A recent study by ^{Valdés et al. (2019)} focused on cognitive processing speed training in 49 older adults with MCI, with three different tasks: i) the Road Sign Test, which tests the reaction time of participants in response to a set of stimuli presented by a computer; ii) The Timed IADL Test, which uses stimuli of instrumental activities of daily living (e.g., reading the directions on a medicine bottle label) presented by a computer; and iii) the UFOV Test, which is a computerized test of cognitive processing speed for visual attention tasks. Conclusions indicated that computer training improved the processing speed in people with MCI.

^{Dethlefs et al. (2017)} conducted a study on 23 participants involved in cognitively stimulating activities (memory and communication tasks) based on processing information, such as sorting, name recall, quiz, and proverbs, for 20 minutes, using the electronic game Wizard-of-Woz (WoZ interface). They showed that this game could improve the spoken natural language of adults with dementia and healthy older people. In turn, ^{Martínez-Alcalá et al. (2018)} used the mobile app iBenni to train attention, memory, comprehension, perception, and visual-spatial processes in a more general sample of 22 older adults and detected gains in attention, comprehension, and short-term memory. ^{Ordonez et al. (2017)} used a cognitive stimulation tool, the electronic games equipment Actively Station, in 124 older adults and confirmed the improvement of language and memory functions and the reduction of anxiety symptoms and memory complaints.

However, not all studies showed positive effects of cognitive stimulation using computer-based assistive technology, especially in studies including older adults with dementia or MCI. Namely, ^{Karssemeijer et al. (2019)}, who used the interactive virtual bike tours Bike Labyrinth in 115 older adults with dementia to train executive function, episodic memory, working memory, and psychomotor speed, confirmed improvements in psychomotor speed but no effects on executive function and episodic and working memory. ^{Yasini and Marchand (2016)} found no significant differences in the trained cognitive functions when increasing the difficulty levels and the time older adults spend using the tablet application Stim'Art. However, although the results showed no gains in the well-being of users, the participants’ self-evaluations reflected an improvement in the well-being score.