1. Introduction

2. Method

2.2. Article Screening and Eligibility

After an initial screening of 61 publications, a set of false-positive keywords was identified and transferred into a list of exclusion terms. This enabled the functionality to exclude the terms from the result list automatically. This function has been applied to the title and keywords of the results. The list of false-positive words is included in the publication and can be found in Appendix D. Application of the exclusion terms excluded seven false-positive publications from the result set. Review Articles were not included in the publication. A selection of the most recent reviews was summarized in the Background Section 1.2. In total, 18 reviews were identified and excluded. After removing false positives based on an exclusion list and excluding reviews from the original result set, 36 articles remained and underwent a manual screening process. The eligibility criteria were defined as follows:

Table 1. Inclusion and Exclusion Criteria for the screening process

Table 1. Inclusion and Exclusion Criteria for the screening process

Criteria Type	Description
Exclusion Criteria	No valid DOI provided or identified through further research. Review articles excluded due to lack of comparability and varying review methodologies. Publication is not available in the English language. Full-text is not available or unobtainable. Focuses solely on evaluating or assessing medical conditions rather than treatment.
Inclusion Criteria	Subjects or patients have a neurological impairment (e.g., Dementia, MCI, Alzheimer’s). The publication focuses on treating medical conditions, not just assessment. Involves using video gaming, exergaming, or gamification as part of the intervention. Full-text is available or obtainable for in-depth analysis.

The above-stated eligibility criteria were sufficient for 19 publications. Seventeen publications were excluded.

2.3. Investigation Scope

After the initial review and the application of the eligibility criteria, the 19 remaining publications underwent manual screening and full-text analysis. Within the process, certain Variables were defined and gathered from the publications and their available meta-data.

2.3.1. Bibliographic Variables

Bibliographic variables help to understand basic information about the publication. Two bibliographic variables turned out to be relevant for further investigation and visualization.

Table 2. Description of Bibliographic Variables

Table 2. Description of Bibliographic Variables

Variable	Description
Year of Publication	Represents the paper’s first publication year.
Country of Origin	To create geographical context, the Country of Origin of the publication has been extracted. In the case of multiple authors and affiliations to different organizations, the extracted country is the first affiliation of the first author.

2.3.2. Medical Variables

In a medical context, variables like the medical condition, advancement of clinical trials, participation in clinical trials and engagement intensity are applied to gain insight into the state of research.

Table 3. Clinical Research Variables and Descriptions

Table 3. Clinical Research Variables and Descriptions

Variable	Description
Parkinson’s Disease	ICD code G20.
Advancement of Clinical Research	Looks into the type of trial conducted and referred to in the assessed publication.
Single Case Study	Examination of an individual case to gain in-depth insights into a particular observation.
Pilot Study	A small-scale study conducted to evaluate factors like usability, time, cost, and risks. It does not evaluate treatment effects.
Feasibility Study	Investigations into the viability of a clinical trial, involving control and randomization groups. Fewer participants than in an RCT but more than in a pilot study.
Randomized Clinical Trial (RCT)	Subjects are randomly assigned to intervention groups to evaluate treatment effects and risks compared to a control group.
Participation in Clinical Research	Refers to the number of subjects participating in a clinical trial or study.
Engagement Intensity	A set of numeric values representing the engagement intensity of applied interventions.
Overall period of engagement	Measured in weeks.
Number of weekly sessions	The number of weekly sessions administered.
Average session duration	Duration of a single session, measured in minutes.
Simulator Sickness	Refers to issues of simulator sickness when using AR/VR applications caused by the decoupling of movement and visual signals.

2.3.3. Technical Variables

The following variables have been defined to be investigated to gain technical insight into the development and state of VR/AR applications.

Variable: Immersion Level describes how advanced a System is in terms of immersion. Therefore, we rely on Milgram’s taxonomy on Mixed Reality [16]. Who classified the spectrum of AR and VR soft- and hardware under the term mixed reality for reference, see Figure 2

Milgram et al.’s taxonomy is defined by a 3-axis continuum that creates a space for classifying VR and AR technologies.

• Extent of World Knowledge (EWK) (Real World vs. Artificial (modelled) world)
• Reproduction Fidelity (RP) (Modelling Quality: Wireframes vs. 3D Real-time)
• Extend of Presence Metaphor (EP) (Monitor-based vs. Head Mounted Device)

Extended World Knowledge (EWK) is used to classify whether a system is an AR (with limited World Knowledge) or VR (with perfect World Knowledge) system. The EWK axis is not essential to the result and is left out of this publication. The following system was designed to classify the type of immersion.

• Rating of the variables Extend of Presence: Delivery from 1-3 (Low, Medium, High)
• Rating of the variable Extend of Presence: Controls from 1-3 (Low, Medium, High)
• Rating of Reproduction Fidelity from 1-6 (from simple to realistic)

The results on the Extent of Presence Metaphor (EP) were summed up, and Reproduction Fidelity (RP) values were used to create a coordinate plane (x,y) for the immersion classification. Results of this assessment were plotted on a grid as seen in subsection Immersion Level 3.3.4.

Table 4. Clinical Research Variables and Descriptions: Immersion Assessment

Table 4. Clinical Research Variables and Descriptions: Immersion Assessment

Variable	Description
Extent of Presence: Delivery	Refers to the type of device used to deliver content to the user.
Monitor	Standard display attached to a computer to represent 2D and 3D environments.
180° Projector	Curved 180° view to create an immersive experience and project 2D and 3D environments.
VR Headset	A virtual reality headset (HMD) that immerses the user in a computer-generated 3D environment.
Extent of Presence: Controls	Refers to the type of controllers used to interact with the application.
Wireless Remote	A handheld device to track motion and interact with digital spaces.
Stationary Bike	A fitness bike enabling stationary but active interaction with the digital environment.
Touchscreen	A touch-sensitive screen allows direct digital content interaction.
Body Controller	An infrared motion-tracking device (e.g., Microsoft Xbox Kinect) that tracks body movements.
Green screen	A film technique to replace the background with computer-generated graphics.
Classic Gaming Controller	A handheld controller commonly used with computers or gaming consoles.
Hand Motion Tracker	A device to track hand and finger gestures for interaction with the application.
Reproduction Fidelity	Assesses and rates the maturity and quality of the application on a scale from 1 to 6. A score of 1 represents simple sounds and graphics, while 6 represents a realistic real-time simulation.
Immersion Level	The Extent of Presence Metaphor (EP) and Reproduction Fidelity (RP) values are used to classify immersion levels, plotted on a grid as seen in subsection Immersion Level Section 3.3.4.
Autonomy and Guidance	Represents the patient’s autonomy while using the application.
Supervised	The patient uses the application under supervision.
Unsupervised	The patient uses the application without supervision.

3. Results

3.2. Medical Results

The section focuses on medical results and findings within the publications. The following information has been searched for: advancement of clinical research, participation in clinical research, patient engagement intensity, and simulator sickness.

3.2.1. Advancement of Clinical Research

The size and participation in clinical research activities are good indicators of the maturity of the research field. Publications are classified as Randomized Clinical Trials, Pilot Studies, Feasibility Studies, Design Studies and Single Case Studies, all explained in Section 2.3.2 Medical Variables.

Table 6. Number of Publications by Study Type

Table 6. Number of Publications by Study Type

Study Type	Publications
Randomized Clinical Trial (RCT)	8
Pilot Study	5
Feasibility Study	4
Design Study	1
Single Case Study	1

Considered together with section Participation in Clinical Research  3.2.2, the above metric provides an insight into the maturity of the research field and its ongoing projects.

3.2.2. Participation in Clinical Research

The participation numbers of clinical trials are essential to provide realistic numbers for significance, sample size and reliability. Together with the variable Advancement in Clinical Research, Section 3.2.1, this measurement is represented in Figure 4.

3.2.3. Engagement Intensity

This section describes the Intensity of Engagement that a trial participant experiences. Three elements describe the engagement intensity.

(1)

Overall period of engagement with the application. As depicted in Figure 5 Overall duration of engagement.

(2)

Number of weekly sessions dispensed, As shown in Figure 6 Number of weekly sessions.

(3)

The average duration of a single session, measured in minutes and visualized in Figure 7 Single session duration.

The following three images show variations in overall publication numbers. The descriptions of the following three figures clarify the total numbers of the datasets.

Figure 5. Overall duration of study/trial Visualization of the overall duration of the clinical trial in weeks. The three dotted vertical lines represent the lower quartile (4,75 weeks), median (10 weeks) and upper quartile (24 weeks). The grey dots represent the individual trial. The dark blue violin plot visualizes the distribution of publications and weeks (n = 16).

Figure 5. Overall duration of study/trial Visualization of the overall duration of the clinical trial in weeks. The three dotted vertical lines represent the lower quartile (4,75 weeks), median (10 weeks) and upper quartile (24 weeks). The grey dots represent the individual trial. The dark blue violin plot visualizes the distribution of publications and weeks (n = 16).

Figure 6. Number of weekly sessions Weekly number of applied sessions over the total number of weeks. Measured in sessions per week. The three dotted vertical lines represent lower quartile (2 times a week), median (2 times a week) and upper quartile (3 times a week). The grey dots represent the conducted trial. The dark blue violin plot visualizes the distribution of publications and weeks (n = 15).

Figure 6. Number of weekly sessions Weekly number of applied sessions over the total number of weeks. Measured in sessions per week. The three dotted vertical lines represent lower quartile (2 times a week), median (2 times a week) and upper quartile (3 times a week). The grey dots represent the conducted trial. The dark blue violin plot visualizes the distribution of publications and weeks (n = 15).

Figure 7. Single session duration Duration of a single session. Measured in minutes. The three dotted vertical lines represent lower quartile (30 min), median (40 min) and upper quartile (60 min). The grey dots represent the conducted trial, and the dark blue violin plot visualizes the distribution of publications and administered minutes for the individual trial (n = 16).

Figure 7. Single session duration Duration of a single session. Measured in minutes. The three dotted vertical lines represent lower quartile (30 min), median (40 min) and upper quartile (60 min). The grey dots represent the conducted trial, and the dark blue violin plot visualizes the distribution of publications and administered minutes for the individual trial (n = 16).

3.2.4. Simulator Sickness

Of the 19 publications, 14 contained no information on the topic. Three publications mention that no simulator sickness was reported during the clinical trial.

Zhu et al. are applying an HMD to the Virtual Supermarket Application report of one patient who reported simulator sickness, but it went away after the fifth session [18]. The team of the GRAIL System, a 180°walking simulator published by Amaefule et al. in 2022 [19], identified 1 out of 13 subjects had problems with Simulator Sickness.

In summary, the average clinical trial in VR and AR gaming in preventing dementia over the last 12 years includes 23,5 subjects, follows a protocol lasting ten weeks, has an average of 2 sessions per week, and is 40 minutes long per session. Simulator Sickness is either not present or not reported.

3.3. Technical Results

The Technical Results section considers Device Type, Device Controls, and Immersion Level variables. A first look at Autonomy and Guidance will give insight into whether a patient needs guidance and supervision during use.

3.3.1. Extend of Presence: Delivery

The variable of how the virtual world is delivered to the patient is partly defined by the Computer Output Device. Milgram et al. describe the delivery Method as the Extend of Presence (EP)[16] suggests. The regular TV screen has a lower score, and more advanced VR and AR systems result in a higher score on the EP axis. EP forms the y-axis above in the Figure 8.

Table 7. Number of Publications by Display Type

Table 7. Number of Publications by Display Type

Display Type	Publications
TV Screen	11
HMD (Head-Mounted Display)	6
180° Screen	1
Tablet	1

The German researchers Amaefule et al. built a walking simulator featuring a 180°Field of View provided by a projector in front of an extra-wide treadmill [19]. This is to be seen as the first applied to VR and AR research in dementia treatment. The benefits are ease of use for the patient and great immersion without relying on HMDs to generate the immersion. Through the walking speed, the surrounding 3D environment can be controlled.

3.3.2. Extend of Presence - Controls

This variable, which influences the Extent of Presence in the virtual world, focuses on the controls used to interact with the environment. A versatile controller can significantly improve the user experience and create a more profound sense of immersion, while a poorly chosen controller can ruin it.

Table 8 shows the controllers used within the publications and their distribution.

Table 8. Number of Publications by Controller Type

Table 8. Number of Publications by Controller Type

Controller Type	Publications
Stationary Bike	5
Wireless Remote	4
Classic Gaming Controller	2
Body Controller	2
Treadmill	2
Greenscreen	1
Hand Motion Tracker	1
Driving Simulator	1
Touchscreen	1

The stationary bike is the main used input controller and appears in 5 publications. This is followed by the wireless remote, which has been used four times, and applications where the body is used as an input device (e.g., Mircosoft Xbox Kinect). Other publications use treadmills (n=2), green screens, classic controllers, hand-motion trackers, driving simulators, and touch screens. (n=19) That makes choosing the suitable controller in line with the user’s interaction needs in the environment is essential. This selection ensures users comfortable interaction and navigation within the digital realm and improves comfort and the feeling of immersion.

3.3.3. Reproduction Fidelity

The Reproduction Fidelity (RP), as proposed by Milgram’s taxonomy [16], distinguishes certain levels of quality of how virtual entities are modelled and rendered within the VR and AR environment. Minimalist graphic and sound environments score low (1), and most advanced real-time realistic audio and video productions score high (6). Most applications feature a mediocre quality in terms of Reproduction fidelity. Ten publications have an average rating of 3. Only 5 of 19 publications delivered a state-of-the-art audiovisual experience. Four of the 19 were ranked below average. The total results are displayed in Table 9.

3.3.4. Immersion Level

The Immersion Level is essential to the application’s acceptance and effect. A combination of Extend of Presence (EP) and Reproduction Fidelity (RP) visualizes the publication’s location on the grid.

The combination of Extent of Presence (EP) and Reproduction Fidelity (RP) influences the combined Immersion Level of an AR/VR application. The Immersion Level is a key factor in how convincing the technology is for users. It reflects how much a person feels like they are part of the virtual world.

In Figure 8, you can see how the Immersion Level is mapped out, with RP on the x-axis and EP on the y-axis, ranging from 1 to 6. The visualization shows where different studies fall on the scale of immersion, with those positioned towards the upper right corner being studies that demonstrate high levels of both presence and fidelity.

In short, achieving a high level of immersion is all about getting the right mix of delivery methods, control systems, and how the environment is reproduced.

3.3.5. Autonomy and Guidance

The Autonomy and Guidance section answers whether supervision is needed during an application. Ideally, a patient could use the application without help and oversight, resulting in redacted care and treatment costs. The benefit of supervised solutions is that immediate assistance can be given to guide the patient to a secure and ideal applied performance of the exercise. Progress and feedback on inventions and applications can be provided in real-time. Furthermore, the patient might benefit from social interaction with the supervisor. The autonomic approach improves skills of independence and interaction without constant monitoring and feedback. When an application is used, a patient gains flexibility in the conduction, timing, and intensity levels.

Table 10. Number of Publications by Supervision Status

Table 10. Number of Publications by Supervision Status

Supervision Status	Publications
Supervised	16
Not Supervised	3

The majority of reviewed publications use a supervision approach. Only three publications (n=19) used autonomous interaction with the patient.

Two of the three publications are conducted by Anderson-Hanley et al. and feature a 2D cycling simulator that can also be used at home, see [19,20]. The third unsupervised application from van der Kolk et al. also features a cycling simulator called Cybercycle, which can be ridden autonomously [21].

4. Discussion

Abbreviations

References

1. Crimmins, E.M.; Kim, J.K.; Langa, K.M.; Weir, D.R. Assessment of Cognition Using Surveys and Neuropsychological Assessment: The Health and Retirement Study and the Aging, Demographics, and Memory Study. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences 2011, 66B, i162–i171. [Google Scholar] [CrossRef]
2. Park, M.J.; Kim, D.J.; Lee, U.; Na, E.J.; Jeon, H.J. A Literature Overview of Virtual Reality (VR) in Treatment of Psychiatric Disorders: Recent Advances and Limitations. Frontiers in Psychiatry 2019, 10, 505. [Google Scholar] [CrossRef]
3. DGPPN – DGN., Ed. S3-Leitlinie Demenzen; Springer Berlin Heidelberg: Berlin, Heidelberg, 2017. [CrossRef]
4. Roberts, R.; Knopman, D.S. Classification and Epidemiology of MCI. Clinics in Geriatric Medicine 2013, 29, 753–772. [Google Scholar] [CrossRef]
5. World Health Organization. Risk reduction of cognitive decline and dementia: WHO guidelines; World Health Organization: Geneva, 2019. [Google Scholar]
6. Kim, C.K.; Lee, Y.R.; Ong, L.; Gold, M.; Kalali, A.; Sarkar, J. Alzheimer’s Disease: Key Insights from Two Decades of Clinical Trial Failures. Journal of Alzheimer’s Disease 2022, 87, 83–100. [Google Scholar] [CrossRef]
7. Meyer, C.; O’Keefe, F. Non-pharmacological interventions for people with dementia: A review of reviews. Dementia 2020, 19, 1927–1954. [Google Scholar] [CrossRef]
8. Rodrigo-Yanguas, M.; González-Tardón, C.; Bella-Fernández, M.; Blasco-Fontecilla, H. Serious Video Games: Angels or Demons in Patients With Attention-Deficit Hyperactivity Disorder? A Quasi-Systematic Review. Frontiers in Psychiatry 2022, 13, 798480. [Google Scholar] [CrossRef]
9. Pallavicini, F.; Pepe, A.; Mantovani, F. Commercial Off-The-Shelf Video Games for Reducing Stress and Anxiety: Systematic Review. JMIR Mental Health 2021, 8, e28150. [Google Scholar] [CrossRef]
10. Bogost, I. The rhetoric of exergaming. Proceedings of the Digital Arts and Cultures (DAC) 2005, 51. [Google Scholar]
11. Muñoz-Saavedra, L.; Miró-Amarante, L.; Domínguez-Morales, M. Augmented and Virtual Reality Evolution and Future Tendency. Applied Sciences 2020, 10, 322. [Google Scholar] [CrossRef]
12. Flynn, A.; Healy, D.; Barry, M.; Brennan, A.; Redfern, S.; Houghton, C.; Casey, D. Key Stakeholders’ Experiences and Perceptions of Virtual Reality for Older Adults Living With Dementia: Systematic Review and Thematic Synthesis. JMIR serious games 2022, 10, e37228. [Google Scholar] [CrossRef]
13. Yen, H.Y.; Chiu, H.L. Virtual Reality Exergames for Improving Older Adults’ Cognition and Depression: A Systematic Review and Meta-Analysis of Randomized Control Trials. Journal of the American Medical Directors Association 2021, 22, 995–1002. [Google Scholar] [CrossRef]
14. Gates, N.J.; Rutjes, A.W.; Di Nisio, M.; Karim, S.; Chong, L.Y.; March, E.; Martínez, G.; Vernooij, R.W. Computerised cognitive training for 12 or more weeks for maintaining cognitive function in cognitively healthy people in late life. The Cochrane Database of Systematic Reviews 2020, 2, CD012277. [Google Scholar] [CrossRef]
15. PubMed Database.
16. Milgram, P.; Takemura, H.; Utsumi, A.; Kishino, F. Augmented reality: a class of displays on the reality-virtuality continuum; , 1995; pp. 282–292. [CrossRef]
17. Anderson-Hanley, C.; Arciero, P.J.; Brickman, A.M.; Nimon, J.P.; Okuma, N.; Westen, S.C.; Merz, M.E.; Pence, B.D.; Woods, J.A.; Kramer, A.F.; Zimmerman, E.A. Exergaming and older adult cognition: a cluster randomized clinical trial. American Journal of Preventive Medicine 2012, 42, 109–119. [Google Scholar] [CrossRef]
18. Zhu, K.; Zhang, Q.; He, B.; Huang, M.; Lin, R.; Li, H. Immersive Virtual Reality-Based Cognitive Intervention for the Improvement of Cognitive Function, Depression, and Perceived Stress in Older Adults With Mild Cognitive Impairment and Mild Dementia: Pilot Pre-Post Study. JMIR serious games 2022, 10, e32117. [Google Scholar] [CrossRef]
19. Amaefule, C.O.; Lüdtke, S.; Kirste, T.; Teipel, S.J. Effect of Spatial Disorientation in a Virtual Environment on Gait and Vital Features in Patients with Dementia: Pilot Single-Blind Randomized Control Trial. JMIR serious games 2020, 8, e18455. [Google Scholar] [CrossRef]
20. Anderson-Hanley, C.; Barcelos, N.M.; Zimmerman, E.A.; Gillen, R.W.; Dunnam, M.; Cohen, B.D.; Yerokhin, V.; Miller, K.E.; Hayes, D.J.; Arciero, P.J.; Maloney, M.; Kramer, A.F. The Aerobic and Cognitive Exercise Study (ACES) for Community-Dwelling Older Adults With or At-Risk for Mild Cognitive Impairment (MCI): Neuropsychological, Neurobiological and Neuroimaging Outcomes of a Randomized Clinical Trial. Frontiers in Aging Neuroscience 2018, 10, 76. [Google Scholar] [CrossRef]
21. van der Kolk, N.M.; de Vries, N.M.; Kessels, R.P.C.; Joosten, H.; Zwinderman, A.H.; Post, B.; Bloem, B.R. Effectiveness of home-based and remotely supervised aerobic exercise in Parkinson’s disease: a double-blind, randomised controlled trial. The Lancet. Neurology 2019, 18, 998–1008. [Google Scholar] [CrossRef]
22. Karssemeijer, E.G.A.; Bossers, W.J.R.; Aaronson, J.A.; Sanders, L.M.J.; Kessels, R.P.C.; Olde Rikkert, M.G.M. Exergaming as a Physical Exercise Strategy Reduces Frailty in People With Dementia: A Randomized Controlled Trial. Journal of the American Medical Directors Association 2019, 20, 1502–1508. [Google Scholar] [CrossRef]
23. Iliadou, P.; Paliokas, I.; Zygouris, S.; Lazarou, E.; Votis, K.; Tzovaras, D.; Tsolaki, M. A Comparison of Traditional and Serious Game-Based Digital Markers of Cognition in Older Adults with Mild Cognitive Impairment and Healthy Controls. Journal of Alzheimer’s disease: JAD 2021, 79, 1747–1759. [Google Scholar] [CrossRef]
24. Torpil, B.; Şahin, S.; Pekçetin, S.; Uyanık, M. The Effectiveness of a Virtual Reality-Based Intervention on Cognitive Functions in Older Adults with Mild Cognitive Impairment: A Single-Blind, Randomized Controlled Trial. Games for Health Journal 2021, 10, 109–114. [Google Scholar] [CrossRef]
25. Hsieh, C.C.; Lin, P.S.; Hsu, W.C.; Wang, J.S.; Huang, Y.C.; Lim, A.Y.; Hsu, Y.C. The Effectiveness of a Virtual Reality-Based Tai Chi Exercise on Cognitive and Physical Function in Older Adults with Cognitive Impairment. Dementia and Geriatric Cognitive Disorders 2018, 46, 358–370. [Google Scholar] [CrossRef]
26. Zając-Lamparska, L.; Wiłkość-Dębczyńska, M.; Wojciechowski, A.; Podhorecka, M.; Polak-Szabela, A.; Warchol, L.; Kędziora-Kornatowska, K.; Araszkiewicz, A.; Izdebski, P. Effects of virtual reality-based cognitive training in older adults living without and with mild dementia: a pretest-posttest design pilot study. BMC research notes 2019, 12, 776. [Google Scholar] [CrossRef]
27. Huang, L.C.; Yang, Y.H. The Long-term Effects of Immersive Virtual Reality Reminiscence in People With Dementia: Longitudinal Observational Study. JMIR serious games 2022, 10, e36720. [Google Scholar] [CrossRef]
28. Hassandra, M.; Galanis, E.; Hatzigeorgiadis, A.; Goudas, M.; Mouzakidis, C.; Karathanasi, E.M.; Petridou, N.; Tsolaki, M.; Zikas, P.; Evangelou, G.; Papagiannakis, G.; Bellis, G.; Kokkotis, C.; Panagiotopoulos, S.R.; Giakas, G.; Theodorakis, Y. A Virtual Reality App for Physical and Cognitive Training of Older People With Mild Cognitive Impairment: Mixed Methods Feasibility Study. JMIR serious games 2021, 9, e24170. [Google Scholar] [CrossRef]
29. Oliveira, L.M.; Evangelista E Souza, E.H.; Alves, M.R.; Carneiro, L.S.F.; Fagundes, D.F.; de Paula, A.M.B.; Engedal, K.; Nascimento, O.J.M.; Monteiro-Junior, R.S. 2D Virtual Reality-Based Exercise Improves Spatial Navigation in Institutionalized Non-robust Older Persons: A Preliminary Data Report of a Single-Blind, Randomized, and Controlled Study. Frontiers in Neurology 2020, 11, 609988. [Google Scholar] [CrossRef]
30. Masoumzadeh, S.; Moussavi, Z. Does Practicing with a Virtual Reality Driving Simulator Improve Spatial Cognition in Older Adults? A Pilot Study. Neuroscience Insights 2020, 15, 2633105520967930. [Google Scholar] [CrossRef]
31. Yun, S.J.; Kang, M.G.; Yang, D.; Choi, Y.; Kim, H.; Oh, B.M.; Seo, H.G. Cognitive Training Using Fully Immersive, Enriched Environment Virtual Reality for Patients With Mild Cognitive Impairment and Mild Dementia: Feasibility and Usability Study. JMIR serious games 2020, 8, e18127. [Google Scholar] [CrossRef]
32. Fasilis, T.; Patrikelis, P.; Siatouni, A.; Alexoudi, A.; Veretzioti, A.; Zachou, L.; Gatzonis, S.S. A pilot study and brief overview of rehabilitation via virtual environment in patients suffering from dementia. Psychiatrike = Psychiatriki 2018, 29, 42–51. [Google Scholar] [CrossRef]
33. Burdea, G.; Polistico, K.; Krishnamoorthy, A.; House, G.; Rethage, D.; Hundal, J.; Damiani, F.; Pollack, S. Feasibility study of the BrightBrainer™ integrative cognitive rehabilitation system for elderly with dementia. Disability and Rehabilitation. Assistive Technology 2015, 10, 421–432. [Google Scholar] [CrossRef]
34. Cornejo Thumm, P.; Giladi, N.; Hausdorff, J.M.; Mirelman, A. Tele-Rehabilitation with Virtual Reality: A Case Report on the Simultaneous, Remote Training of Two Patients with Parkinson Disease. American Journal of Physical Medicine & Rehabilitation 2021, 100, 435–438. [Google Scholar] [CrossRef]
35. McEwen, D.; Taillon-Hobson, A.; Bilodeau, M.; Sveistrup, H.; Finestone, H. Two-week virtual reality training for dementia: Single case feasibility study. Journal of Rehabilitation Research and Development 2014, 51, 1069–1076. [Google Scholar] [CrossRef]