Duplicates from the initial search results were removed using the EndNote software (Clarivate Analytics) [38]. The remaining results were then imported to Covidence [39] for title, abstract, and full-text screening. In total, 2 researchers independently screened the titles and abstracts based on the inclusion and exclusion criteria. Disagreements were first discussed between the 2 researchers. A third researcher was involved if an agreement could not be reached. The remaining studies then underwent full-text screening by 1 researcher using the same inclusion and exclusion criteria. The decision to have a single reviewer conduct the full-text screening was due to time limitations and the limited availability of the reviewers, which made it challenging to conduct this dual-reviewer process. To avoid potential bias and ensure rigor in the screening process, several steps were taken. First, we used clear, predefined inclusion and exclusion criteria to guide the reviewer’s decision during full-text screening. Second, to minimize errors and ensure consistency, the reviewer sought a second opinion from the coauthors for any ambiguous cases encountered during full-text screening. In addition, the reviewer conducted a random sample check of the included studies to assess agreement. Although full-text screening only involved 1 reviewer, it is important to note that dual reviewers were involved during title and abstract screening to enhance accuracy and reduce bias.

Studies were included if all the inclusion criteria were met: (1) the studies included people living with dementia who lived in the community, their informal caregivers, or both; (2) the studies focused on apps used in dementia care; (3) the studies used smartphones, tablet computers, or handheld computers; and (4) the studies conducted a usability evaluation of the app with end users.

The exclusion criteria were as follows: (1) studies that involved nonhuman participants; (2) studies that included only healthy participants or people living with dementia who lived in a nursing home, a care facility, or long-term care; (3) studies that involved apps developed for health care professionals, such as nurses, physicians, therapists, clinicians, or professional caregivers; (4) studies that included apps focused on dementia cognition assessment or diagnoses; (5) studies focused only on a conceptual app, the description and design process, or app development without user evaluation; (6) review studies, such as literature reviews or systematic reviews; (7) studies that were not peer-reviewed, such as preprints; and (8) presentations, protocols, commentaries, abstracts, supplements, or posters.

A total of 76% (38/50) of the apps were used specifically for people living with dementia, whereas 12% (6/50) were developed solely for caregivers [66,67,74,75,79,80] and 12% (6/50) were developed for both people living with dementia and their informal caregivers [60,68,71,82,84,85]. In total, 60% (30/50) of the apps had a single feature, meaning that an app served a single purpose, such as apps for reminders, reminiscence, or brain games [84]. A total of 40% (20/50) of the apps had multiple features, meaning that different features were brought into 1 app platform, such as an app offering both reminiscence and reminder features [84]. It should be noted that 60% (12/20) of the multiple-feature apps were tested most recently in 2020 and 2021. The following sections will discuss the features of the apps used by people living with dementia followed by those of the apps used by informal caregivers.

Multimedia Appendix 7 provides a summary of the features of the apps for people living with dementia. Among the 32 studies, apps focusing on cognitive stimulation were the most common (n=17, 53%), followed by reminders or prompts for people living with dementia to complete ADLs (n=13, 41%), social support (n=12, 38%), and scheduling for people living with dementia (n=7, 22%).

Among the cognitive stimulation apps, reminiscence was the most common approach, followed by brain games. The most common features of reminiscence included but were not limited to viewing old photos and videos from their past and listening to familiar music [45,50]. Ryan et al [45] found that people living with dementia enjoyed viewing their old photos the most, followed by listening to familiar music and viewing videos. People living with dementia preferred personalized media rather than general media [49]. Similarly, another study found that people living with dementia enjoyed nostalgic songs with which they were familiar. The study also found that participants happily danced to the music [72]. People living with dementia loved interacting with their own old photos, photos of their family and friends, and photos of family holidays they spent together [45,49,59].

Reminder apps included reminders for taking medication [57-59,81,84], appointments (ie, meeting with family physicians or friends) [57,63,65,68,84], daily activities (ie, watch the favorite TV show) [52,59,86], mealtimes [59,81], special events (ie, birthdays) [56,84], religious events (ie, prayer time and church visits) [59,84], doing chores [84], and weather reminders (ie, warning of rain and snow) [59]. In total, 7% (3/44) of the studies focused on apps providing step-by-step prompts for people living with dementia to complete daily tasks, such as making a phone call or a cup of coffee [69,76,86].

There were 6 kinds of social support offered by the apps. First, connection referred to the app’s ability to give people living with dementia quick access to the contact information of their family or friends and other essential people (eg, family physician). A photo or the relationship between the contact person and the user would be displayed to help people living with dementia quickly identify them. Second, recognition meant that the app helped people living with dementia identify a person, face, or object. Third, calling for help was a feature that allowed people living with dementia to call a predefined contact person (ie, usually informal caregivers) if help was needed. Fourth, needs support referred to specific assistance for people living with dementia to meet their daily needs with the help of their caregivers [59]. For example, a task message would be sent to the predefined informal caregivers regarding the request of people living with dementia using the app [59]. Fifth, communication aids meant that the app offered an augmentative and alternative communication method to help improve the communication of people living with dementia [62]. Finally, location-based review referred to the app’s ability to allow users to provide a review and rating of a location they visited [85].

Multimedia Appendix 8 identifies and describes the app features used in dementia care that targeted informal caregivers as the end users. The most common features of the apps included activities that enabled caregivers to engage the people living with dementia in an activity or task (eg, playing a game together) [60,67,75,82] and providing caregiving support [66,67,75,79].

Most studies (36/44, 82%) showed that participants had a positive experience interacting with the app. Participants from 7% (3/44) of the studies, which assessed a cognitive stimulation game app [88], a facial recognition app [70], and an app to help people living with dementia with ADLs [58], explicitly expressed that these apps were not useful and showed low interest in using the apps in dementia care [58,70,88]. The cognitive stimulation game app was described as unsuitable for people living with dementia because of its complexity [88] and the fact that people living with dementia would constantly require help from a third person to use the app successfully [88]. People living with dementia reported that they did not think the facial recognition app was useful and that it would not affect their social interactions or QOL. Thus, people living with dementia did not want to continue using the app after study completion [70]. In the study by Lai et al [58], the authors developed an app with 4 features: simplified phone calls or SMS text messages to friends or family members, reminders, 1-click emergency calls, and a simplified navigation system for people living with dementia. The results showed that people living with dementia had low interest in the app even after a demonstration. People living with dementia were against the idea of having too much interference from the caregivers in their life. For example, participants living with dementia did not like caregivers updating their appointments remotely or being able to view or monitor their location [58].

Only 2% (1/44) of the studies mentioned accessibility and the barrier to internet access for people living with dementia in rural settings compared with urban settings [60]. A total of 9 themes were identified from app usability testing, which are described in the following sections.

The studies highlighted that apps should be intuitive to use [46,65,71,80], which could enhance the learnability of people living with dementia [65] and facilitate independent app use [61]. The text and icons should be large enough to improve readability for people living with dementia and older adults, especially individuals with vision problems [50,52,61,71,88] or limited dexterity, which reduces their ability to tap or hold the icon or button [61,88]. Please see Table 1 for more detail.

People living with dementia may face challenges when using mobile devices because of their vision [52,60,61,71] or hearing impairments [47], loss of touch sensation, motor impairments (ie, hand tremors or spasms), or physical pain [47,78]. One study indicated that physical pain could reduce the time required to use an app or serve as a distraction from the pain [47]. Issues such as glare could make it even worse for people living with dementia [73,87], so it was recommended to use a screen protector to reduce glare [73]. Some people living with dementia may not be able to hold the device while interacting with it because of its size and weight [61,73] and their reduced dexterity [61,88]. One study reported that people living with dementia might find it hard to use the keyboard to type because of poor hand coordination or swollen fingers [57,61]. People living with dementia may accidentally press unintended screen items, or their finger may rest on the screen by accident to better hold the device [88]. As such, a stylus or tablet pen could ease the dexterity issue and reduce the screen’s unintended touch [57,88].

Owing to vision problems, people living with dementia may prefer a bigger screen [52,73]. However, there was no consensus regarding the size of the tablets for people living with dementia. One study concluded that the screen should not be smaller than 10.2 inches [73]. Although some people living with dementia preferred a bigger screen, others thought the smaller size, such as a 7-inch touch screen, would be more portable [47,52,57,73,74,88].

The studies reported that people living with dementia may be unable to choose the correct widget or app icon [65,101] and may not understand how to swipe, tap, or drag icons to navigate various apps [54,101]. For example, people living with dementia may use the top of the fingernail to swipe instead of a fingertip. It was found that older adults, especially people living with dementia, were not sensitive to the difference between using fingernails and fingertips to respond [73]. In addition, people living with dementia may press a widget or home screen for too long and accidentally delete or edit the home screen [57,101]. Instead of tapping the screen, some people living with dementia may tend to drag their fingers across the screen [73]. People living with dementia may find it challenging to touch the interface accurately and accidentally press the taskbar instead of the app button [65,73].

One usability study indicated that there may be a reported discrepancy between people living with dementia and their informal caregivers [58], specifically that people living with dementia may not realize how often they forget appointments or become disoriented outdoors. In contrast, informal caregivers who provide daily care may be more cognizant of these incidents. For instance, people living with dementia may not believe that apps with navigation or reminder features are useful or relevant to them as much as their caregivers do [58].

A new app related to dementia care could make people living with dementia feel stigmatized. For example, an app makes people living with dementia feel incompetent in remembering or performing their daily tasks, which could result in unwillingness to use the app [29,54,58,69]. One study revealed that people living with dementia could have a negative experience with a game app because of the fear that their cognitive impairment will be exposed [54]. A study on using a prompt app to remind people living with dementia to complete daily tasks also suggested that people living with dementia might feel embarrassed using the app as high use levels may highlight their memory loss [69].

Despite the ubiquity of smart devices nowadays, many older adults still have limited experience with mobile technology [60,61,66]. Lack of experience with technology could result in fear of using it [57,60,62,66]. The study by Ekström et al [62] found that users were new to operating a tablet with an app to aid communication. One participant living with dementia was unfamiliar with the tablet, making them more insecure when using the device, so they were more passive during a conversation [62]. Similar results were found in another study, where participants unfamiliar with tablets were more insecure about using the tablet and app [57]. One study concluded that an 11-week study period might not be sufficient for users to get used to a new app [66].

In contrast, users are more likely to engage with an app if they have more experience with mobile technologies [49,63,69]. Users are more confident in learning to use the app and more likely to use it daily [47,49,57,69]. One study found that users with more technological experience rated app usability higher [75]. Another study showed that a participant living with dementia had a positive experience using a reminder app because of her familiarity with smartphones [63].

As mentioned previously, technological experience can play an important role in app use. Users need to receive training or instructions to understand apps and mobile devices [50,61]. Training or instructions will help build confidence so users will feel more comfortable using the app [61]. The studies indicated that people living with dementia would need the training to use an app and prefer a demonstration to show them how to use the app and mobile device rather than explore the app and device themselves [57,63,86]. One of the studies pointed out that the importance of a proper introduction to the app could motivate the participants’ independent use, especially for those with less experience with the technology. It also emphasized modifying the instruction level according to the user’s technology experience [57]. The users also appreciated the paper-based manual of the app to help them remember how to use it [57,80].

In addition, support from users’ own networks, such as friends and family, is important [47,60,69]. It was found that both people living with dementia and their informal caregivers would need support during technology use, which is especially true for people living with dementia [60]. People living with dementia often turn to their children or grandchildren for assistance as they are relatively more technologically savvy [60]. People living with dementia may prefer that family members help set up the app to use it successfully [70]. Some people living with dementia may find it useful to connect with other users of the same app for technological issues [47,60]. As users may constantly have questions about a new app or device, it would be crucial to have continuous support, such as from a written manual or a contact person, when a question is raised [80,82]. Ongoing support would also help with app retention [82].

To the best of our knowledge, this is the first systematic review to examine the landscape of available apps in dementia care for both people living with dementia and their informal caregivers in a home environment. Notably, our review identified and analyzed various app features, highlighting the most investigated aspects for people living with dementia and their informal caregivers. We also extensively discussed and addressed privacy and safety concerns in app development, including an analysis of app privacy policies. This review offers valuable guidance for selecting appropriate methodologies when conducting usability studies with people living with dementia and their informal caregivers. Finally, we provided a comprehensive overview of app usability outcomes, providing a holistic view of our findings.

The 3 most studied app features for people living with dementia were cognitive stimulation, reminders or prompts to complete ADLs, and social support. As stated in other studies, these activities are considered meaningful for people living with dementia and could potentially improve their QOL [102-104]. Cognitive stimulation is a nonpharmacological intervention that provides various activities to stimulate cognition, such as memory, logical judgment, attention, and language skills [105,106]. It can improve brain function and prevent its degradation [72].

It has been shown that reminiscence greatly affects the cognitive wellness of people living with dementia and improves their QOL [45,107]. However, precautions are needed when conducting reminiscence. It was observed that photos with many people were not recommended as people living with dementia may not be able to identify the faces [52]. In addition, extra attention should be paid when selecting materials for reminiscence to ensure that the materials elicit happy memories and not sad or painful ones [45,61] for the people living with dementia or their informal caregivers [45,108]. For example, photos that remind them of the loss of a family member could be significant for caregivers but not for people living with dementia [108].

Reminders of daily activities could help people living with dementia remain independent [104]. However, not all reminders are preferred by people living with dementia, such as activities that can be performed with their family or friends (eg, taking a walk or checking their blood pressure [59]). As such, an app developed to replace caregivers would not be favored by people living with dementia. Users found the reminder feature useful for daily tasks, including medication times and dosages, religious activities, mealtimes, and appointments [58,59,68,86].

Many people living with dementia live at home [15] with their informal caregivers [8], who greatly influence app adoption for people living with dementia [48,57]. People living with dementia would be more likely to accept an app when their informal caregivers are involved [48,77], and people living with dementia are more engaged when using an app in their caregivers’ presence [77]. The use of apps could allow both people living with dementia and their informal caregivers to spend more time together and increase their feelings of connectedness [47]. For example, apps that prompt conversations and effective communication could enable meaningful dialogue and improve the dyadic relationship and quality time [47]. The development of apps for both people living with dementia and their informal caregivers could have benefits for both types of end users individually as well as strengthening their relationship.

Other studies have shown that receiving support from a caregiving network (ie, help from friends or other family members) could have a beneficial impact on maintaining the QOL of people living with dementia and their informal caregivers [109-111]. Oftentimes, secondary caregivers are involved in care [46,112]. These caregivers could act as mediators to share different care tasks and support [46,109]. Thus, an app with a feature connecting family members or friends involved in care could be useful in the care management of people living with dementia [46].

In addition, special attention should be paid to the app instruction or guide (ie, Help button), personalization (ie, Edit), and rewards features. Although these features were not mentioned in most studies, they are considered incentives and could boost app engagement [77,80,82,86]. It was found that users would greatly appreciate the additional explanation of an app. A Help button with tips or instructions was suggested [47,68,80]. The instructions should be written using lay language to increase accessibility for people living with dementia. Ideally, instructions should be able to adapt to the user’s computer experience [57]. An app should be customizable to meet users’ needs [46,80]. An Edit feature could be added to the app to allow users to change the setting, such as the font size, background, music, and information sharing [57,68,76]. Finally, both people living with dementia and informal caregivers found reward systems beneficial, and these could help motivate their ongoing use of the app [77,80,86].

The results of this review indicate that 60% (30/50) of researched apps were single-feature apps (ie, served 1 purpose), which meant that users needed to download multiple apps to meet their needs [84]. Another limitation is that most apps (39/50, 78%) offered only 1 language. These limitations could significantly restrict the number of users. To make an app more widely used, we recommend having multiple features and offering several languages.

The literature indicates that people living with dementia are concerned about their privacy and security [113,114]. However, this review only identified 1 study that discussed the safety and security concerns of users from the perspective of a home care worker [60]. This suggests that more research is required to examine the perspectives of people living with dementia and their informal caregivers on privacy and security related to mobile apps. Our findings also indicated that privacy and security were not a priority for developers, organizations, and researchers when developing apps based on the few studies that described these privacy features (4/44, 9%). Our findings align with those of previous studies that suggested that developers lack awareness and knowledge when applying security and privacy measures during app production [115,116]. None of the studies described the length of time during which data were stored or whether users could delete their data, which raises critical ethical questions regarding data ownership and private interests related to people living with dementia. This review also revealed that the privacy policies for commercially available apps are inconsistent and lack detail, with important content missing according to the General Data Protection Regulation [117,118].

None of the usability questionnaires used in the studies included security- and privacy-related questions despite 61% (17/28) of the questionnaires being self-developed by the researchers rather than standardized and validated tools. Despite the importance of privacy in technology adoption [16,27,28] and the potential algorithmic bias or harm toward older people (eg, digital ageism [119]), our findings suggest that developers and their organizations have not seriously addressed or investigated the issues related to privacy [120,121]. More research is required to investigate mobile device–related privacy and security, especially as they relate to people living with dementia, as the current research in this area is still in its nascent stages.

Although there are publicly available resources to build privacy and security tools, such as checklists through app stores or computing platforms [116], our findings can be used to further advance a consensus about privacy policies. In particular, the 17 themes from research aim 2 could serve as a general framework to assist developers, organizations, and researchers in creating detailed and concise privacy policies. In addition, we urge organizations to protect users’ data [122,123] proactively, for example, ensuring that a transparent, concise, and valid privacy policy is made available for users and that all web links are active and updated. Finally, more public education about privacy and security risks related to mobile apps can enhance the vigilance of formal and informal caregivers and people living with dementia when choosing or using an app [122,123].

This review found 5 methods to evaluate usability: observations, interviews, focus groups, logging, and questionnaires. Techniques for these methodologies include think aloud, video and audio recordings, and field notes [64,124]. The most commonly used method in our review were questionnaires administered at the end of the intervention. The most commonly used standard questionnaire was the SUS; however, studies found that people living with dementia may not be able to complete the SUS because of its double-negative questions [57,64,86]. Usability questionnaires may not assess the true performance of people living with dementia as questionnaire completion usually occurs after the intervention, which requires recalling the user experience [64,86]. One study compared SUS results between caregivers and people living with dementia [64]. It showed that people living with dementia provided higher ratings on the SUS, meaning that the app was more usable for people living with dementia than for caregivers. However, caregivers’ higher task completion rates suggested that the app was more usable for caregivers [64]. Questions have been raised regarding whether the results of questionnaires are reliable and valid when used to collect complex feedback from people living with dementia [57,64,86]. Similarly, the think-aloud technique was used in several studies; however, the literature indicates that this methodology may be unsuitable for people living with dementia [50,64,71]. The think-aloud process requires users to express their opinions without analyzing their thoughts while performing specified tasks [125]. This method could overload the working memory of people living with dementia and lead them to provide inaccurate information [50,64]. Although the results will depend on the severity of dementia, the aforementioned methods are more prone to errors as they are based on self-report and fallible to recall bias, which would result in inaccurate usability testing [126]. For instance, people living with dementia may provide an answer that they think others would give [126]. Therefore, thoughtful consideration of the methodologies used to engage with people living with dementia is required, and caution may be needed when interpreting the results of unvalidated posttest questionnaires with people living with dementia.

In contrast, observation and logging provide more objective measures. Observation requires researchers to document detailed information about what they see when users interact with an app. The duration and frequency of app use and task completion rate and time could be recorded during observation. To make the results from observation more reliable, in addition to the presence of the observers taking notes, video recording could capture users’ reactions and their words when interacting with an app and then be assessed by 2 researchers independently [64]. Logging was another form of objective data collection, which is the user data generated from the app with detailed user-app interactions (eg, frequency of app or app feature use, duration of app use, and task completion time).

In summary, applying multiple usability evaluation methods is recommended [124]. Combining objective and subjective measures is suggested to better understand users’ needs [47,49,101]. Objective measures are meant to improve the validity and reliability of the usability results. Although logging could be more promising and cost-effective than observation methods as it reduces human involvement in recording and analyzing user-app interactions [126,127], it is also important to consider the methodology that would achieve the most relevant results in the given context. By assessing the suitability of different usability evaluation methods and considering their alignment with the specific research goals, we can ensure that the selected approach not only reduces bias and enhances efficiency but also provides the most meaningful and contextually relevant outcomes. When enrolling people living with dementia to complete questionnaires, precautions should be taken: questionnaires should be understandable, and long questionnaires with jargon and double negatives should be avoided. Some questionnaires, such as the SUS, may not be suitable for people living with dementia [57,64,86].

Our review showed that most studies (36/44, 82%) reported a positive experience of interacting with the apps. A usable and intuitive-use app could increase user engagement [45], help reduce users’ cognitive overload, and build their confidence in using it. In contrast, an unintuitive app could reduce interest in use [69]. A lack of intuitive navigation could also hinder app adoption [58,69]. Our results under research aim 4 could guide researchers or developers in creating new apps to enhance usability for people living with dementia. This body of evidence shows that, although apps used in dementia care are a usable digital intervention that can provide a variety of supports for people living with dementia and their informal caregivers, our results highlight several important design and privacy concerns that should be accounted for in future research.