The increasing longevity of the population, resulting from the continuing decline in birth rates and increasing life expectancy, is transforming the shape of the age pyramid in the European Union, which will lead to a much older population structure [1]. The percentage of older people in relation to the total population will increase considerably over the next decades, when a large part of the baby boom generation reaches retirement age. This, in turn, will lead to an increased burden on working-age people, not only in terms of coping with the social expenditure required by the aging population, but also in terms of the intrafamily effort to care for their elders.

Furthermore, the longevity of the population brings a major challenge given that a significant proportion of older adults suffer from cognitive impairment and/or a significant decrease in memory, which alarmingly reduces their quality of life [2]. With this perspective on the table, it is particularly important to focus on the older people, with the aim of helping to make their lives at this stage active, rewarding, and fulfilling. In this sense, any action aimed at cognitive abilities, such as attention, memory, or concentration, is of particular relevance. A person with cognitive ability without impairment or with limited impairment has, in general, a more stimulating life, better performance, a healthier existence, and a higher predisposition to be an active member of society. It is, therefore, a matter of aging optimally. While mental inactivity may increase the risk of cognitive decline [3], engaging in cognitively stimulating activities may protect against cognitive decline in older age [4].

2. Reminiscence Therapy

Among the stimulation and activity programs aimed at the elderly, reminiscence therapy (RT) is the most effective in improving the quality of life of older people with cognitive impairment ^[5][6][7][8][5,6,7,8]. It consists in thinking about one’s own experiences through the presentation of memory-facilitating stimuli (photographs, images, etc.), using the past as a method to enjoy the communication of the present [5]. RT has proven to be a very powerful and effective cognitive neurorehabilitation technique. RT goes one step further than classical cognitive stimulation, because of the role played by emotions. Memories of events that reinforce the person’s identity usually evoke strong emotions [9]. It has been shown that people with severe cognitive impairments, despite cognitive deficits and despite losing their memory, keep their emotions alive until the end of life [5]. The development and evaluation of psychosocial interventions aimed at benefiting the elderly is a topic of growing interest. In this framework, cognitive stimulation therapies are recommended to maintain cognitive function, functionality, and quality of life of long-lived people [10]. Cognitive intervention is based on the concepts of neuroplasticity [11] and psychostimulation, and t is a highly individualized stimulation [12] adapted to the residual capacities of the person. Within the stimulation and activity programs, it is in RT that reswearchers find the most evidence [13]. RT is centered around shared themes and is often applied in long-term care [14]. Evidence for the efficacy of reminiscence interventions has accumulated over the past few decades. For older people with some degree of cognitive impairment, reminiscence can help improve communication [15], feelings of belonging [16], quality of life [17], mood, wellbeing, and life satisfaction [18]. Last but not least, it has positive effects on cognition [19]. Regarding cognition, a review of RT for dementia that included 22 randomized controlled trials concluded that there was high-quality evidence for a very small benefit associated with reminiscence at the end of treatment (standardized mean difference 0.11; 95% confidence interval 0.00 to 0.23; 14 studies; 1219 participants). Nine studies that included the Mini-Mental State Examination (MMSE) as a cognitive measure concluded that there was high-quality evidence for an improvement at the end of treatment (mean difference 1.87; 95% confidence interval 0.54 to 3.20; 437 participants). As a conclusion, RT had some positive effects on people with dementia in the cognitive domain [5]. Recently, very successful innovative reminiscence interventions have been developed on specific topics of general interest for a large part of the population, such as soccer [16]. However, this type of therapy is expensive and difficult to implement. It requires specialized personnel for the preparation of the necessary material and the follow-up of the RT session. This leads to this type of therapy being performed without continuity, mainly focusing on patients with dementia [8]. However, the benefits of RT may also be useful for healthy older adults [20]. In this sense, reswearchers believe that having an AI-based application to facilitate RT to older people with or without cognitive impairment would lead to an improvement in their quality of life.

3. State of the Art

ResWearchers can find a substantial number of software tools on the market, generally apps, that deals with some aspects of memory loss and cognitive diminishing. A large number of these focus on Alzheimer’s disease, as it is the most common cause of dementia, accounting for an estimated 60% to 80% of cases [21]. In order to analyze their objectives and characteristics, researchwers carried out a study of the most relevant ones found in the most widely used repositories, as well as in repositories in the field of health, such as Play Store, App Store, TIC Salut, CREA, ACTO Dementia, and CEAPAT. The study also includes an analysis of the most recent literature in the field. There are different types of applications depending on who they are intended for: people with cognitive impairment, their caregivers, or medical and care professionals. Applications for caregivers offer advice and tools to improve attention, care and safety of the patient, and location of the person, as well as extensive and updated information on different resources related to Alzheimer’s and other dementias. Applications for people with cognitive impairment can be classified into two main groups, those that provide cognitive stimulation and those for orientation and reminders of daily activities. Apps for medical and care professionals are basically focused on early diagnosis. It is worth mentioning that the apps aimed at caregivers are more numerous than those aimed at professionals. A systematic review of the literature reveals that the existence different studies that analyzed the availability, content, characteristics, and quality of different apps focused on cognitive impairment. A good example of this can be found in [22], where the authors studied the apps available for people suffering from cognitive impairment or Alzheimer’s disease, with the limitation that they are available only in English. The authors concluded that available apps may not meet complex needs and may be difficult to use given the potential reduction in communication ability associated with cognitive impairment. Therefore, they consider it necessary that high-quality apps be developed and rigorously evaluated to determine their feasibility and effectiveness. Along the same lines, in [23], the benefits and limitations of the use of apps in the management and assessment of mild to moderate cognitive defects were analyzed. In this work, it was concluded that apps are mostly useful to support people with cognitive limitations in daily life tasks, especially, in the early diagnosis of this disorder. However, it is considered necessary that new developments of such apps meet the specific needs of older adults. They consider that there is a need to develop apps that are multifunctional, sensitive to the culture of minority populations, easy to read and use, and, when necessary and appropriate, facilitate information sharing with families, providers, and caregivers. Some work can also be found in the literature looking at the use of technology more particular to RT ^{[24][25][26][27]}[24,25,26,27]. These studies, which contained many interesting ideas to consider regarding the interaction of people with cognitive impairment with a technological device in a broad sense (tv, video, computer, cell phone, etc.), basically presented technological resources for the support of RT content. RWesearchers did not find in the literature any technological application/tool that aims to carry out RT, i.e., to guide users through a set of contents on the basis of their reaction to them. The main objective of this entrstudy was to provide older people with a tool that allows them to carry out RT on a regular, individualized, dynamic basis, adapted to their level of cognitive impairment. The continued application of this therapy can help make their life at this stage active, rewarding, and fulfilling. Focused on this goal, rwesearchers were interested in a person-centered approach, analyzing in more depth existing applications aimed at people with cognitive impairment and not so much at their caregivers or medical and care professionals. Of all the applications found and analyzed, researcherswe present a set of nine tools that theywe consider relevant, regarding the ratings and opinions of users, as well as the organizations that support them:

• AlzhUp: Personal memory bank to which the caregiver and family members can contribute. It also incorporates aerobic, calculation, memory, or relaxation games and exercises [28].
• Memory Box: Aims to stimulate long-term memory by storing photographs and audios of everyday experiences while also encouraging conversations and exchanges between an elderly person and the caregiver or family member [29].
• Refresh My Memory—An application to help remember objects and their location, as well as people in the user’s environment [30].
• YoTeCuido Alzheimer: Support application for caregivers and patients. It provides information about Alzheimer’s disease and allows establishing routines and exercises. The main novelty of its contents compared to other available apps is that they are based on the experience of caregivers and family members, as well as patients and professional caregivers [31].
• Backup Memory: Creates a memory album. The app reminds users of their relationship with each family member by showing them photos and videos of past experiences they shared with their family member [32].
• Imentia: Cognitive stimulation based on a series of interactive exercises that train the different cognitive areas: memory, orientation, language, attention, reasoning, comprehension, etc. Each work area has different levels of complexity [33].
• NoMeOlvides: Application made up of a series of mini-games classified in different categories, such as shapes, colors, addition and subtraction, animals, and objects. It uses an assistant that guides the user through the application [34].
• Andzheimer: Through different graphic exercises divided into their corresponding cognitive areas, it tries to enhance memory, attention, language, executive functions, etc. [35].
• Stimulus: It is based on a series of interactive exercises that train the different cognitive processes, attention, perception, working memory, long-term memory, calculation, reasoning, executive functions, etc. [36].

It is also interesting to mention the work of Caros et al., which created a reminiscence chatbot that uses artificial intelligence (AI) technology to drive communication through the use of a combination of photos and questions directed at people over 60 years of age with mild cognitive impairment. They designed a usability study in which users interacted with the system, with help [37]. In order for users to be able to interact with technology in the easiest and most intuitive way possible, it must meet the user’s needs; therefore, usability testing is essential ^[37][38][37,38]. Although this abovementioned work developed a chatbot to generate a conversation with the user from a photo with the aim of generating reminiscence, this application does not evaluate whether or not reminiscence occurs in the user nor does it generate a specific conversation derived from the level of reminiscence detected. As a conclusion of the state of the art of the research carried out, no applications have been found that allow carrying out an RT that meets the characteristics of RT guided by a therapist or a caregiver. Of the nine applications mentioned, AlzhUp and Memory Box are the closest to theour work. These have a common functionality to theour proposal that they call “memory bank”. This functionality consists of encouraging the participation of various family members to include and validate videos or photographs of shared experiences in the application. This point is also an important aspect of theour research since RT is carried out on events that have influenced the life of the elderly person, at both a personal and a family level, as well as at the level of the public environment of the country and the world in general.