Principal Results
In hereby preliminary analysis, it was observed that a specific immersive VR-based cognitive training may improve at least some aspects of visual memory, sustained attention and working memory. A favorable effect of the intervention was seen in the case of the scores of visual memory (correct hits-immediate) and the one-back task (the number of correct responses and omission errors), evaluating working memory and sustained attention.
Comparison with Prior Work
Cognitive training systems aim to improve specific domains or global cognition by engaging users in cognitively demanding tasks. A relatively new research area of growing interest in cognitive interventions concerns the use of VR, which creates a simulated environment that mimics a real or imaginary setting, allowing users to feel as if they are physically present and engage their senses within that virtual world[24]. VR immersion levels can be categorized as low, moderate, or high. VR-HMD, which was used in this study, falls under the high immersion category, which involves stimulating more than two sensory modalities (e.g., vision, hearing, proprioception, and motor skills) with spatially oriented stimuli. Opting for a higher level of immersion is recommended as it can enhance the patient's sense of presence, leading to more pronounced behavioral responses[25].
The potential of immersive VR for cognitive training in the elderly population has gained significant attention in recent years. Meta-analyzes and systematic reviews provide evidence for the efficacy of this type of intervention in various populations, including healthy older adults as well as individuals with mild cognitive impairment (MCI), dementia, and traumatic brain injury[4, 16, 26, 27].
In the present study, we found a significant group*timepoint interaction for visual memory score (correct hits immediate), which suggests that the VR intervention had a positive impact on visual memory performance. This finding is particularly noteworthy as visual memory plays a crucial role in higher cognitive processes[28].
Our finding regarding the visual memory domain improvement aligns with previous research evaluating the effectiveness of VR cognitive interventions among healthy older adults[29, 30]. In the study published by Gamito et al., twenty-five participants, aged 65–85, underwent 12 VR training sessions between the pre-treatment and post-treatment assessments. A significant increase was seen between the two assessments for some neuropsychological measures: visual memory, attention, and cognitive flexibility[29]. In the subsequent study, forty-three healthy older adults were divided into two groups: an experimental group underwent a VR-based cognitive stimulation (two 30-minute sessions per week for six weeks), and an active control group underwent a paper-and-pencil cognitive stimulation. The outcomes were assessed at the baseline and after intervention by well-established cognitive and executive functioning tests (the Frontal Assessment Battery—FAB, the Wechsler Memory Scale-Revised—WMS, the Rey Complex Figure—RCF and the d2 test). The results suggested the positive effects of VR cognitive stimulation on visual memory, attention, executive function, and general cognition[30].
The significant group*timepoint interaction for the subscores of the one-back task, namely the number of correct responses and the number of omission errors, may indicate a positive effect of the VR intervention on working memory and attention. However, no significant effect was seen in the case of working memory and attention CNS-VS scores. Working memory is a cognitive function that is crucial for various daily activities, such as learning, problem-solving, and decision-making. It involves the temporary storage and manipulation of information, while attention is crucial for maintaining focus and selectively processing relevant stimuli[31]. Age-related decline in working memory has been well-documented, with older adults exhibiting deficits in this cognitive domain compared to their younger counterparts[32, 33]. Therefore, interventions enhancing working memory performance in older adults are of great interest.
The current study found a significant group*timepoint interaction for the number of correct responses in the one-back task. This finding suggests that the VR intervention may have a positive impact on the participants' working memory performance. However, it was not confirmed for a combined CNS-VS working memory score. The improvement in the number of correct responses indicates enhanced accuracy and efficiency in retrieving and manipulating information in working memory[34]. This finding aligns with previous studies that have reported improvements in working memory performance following VR interventions[35, 36].
Furthermore, the significant group*timepoint interaction for the number of omission errors in the one-back task provides additional support for the positive effects of the VR intervention on attention. Omission errors, also known as false negatives, occur when participants fail to respond to a target stimulus. They reflect lapses in attention and can be indicative of attentional deficits[37]. The reduction in omission errors observed in the VR intervention group suggests that the intervention enhanced attentional processes, leading to improved detection and response to target stimuli. This finding is consistent with previous research showing that VR interventions can enhance attentional performance.[38, 39]
However, it is necessary to note that our results were not statistically significant for the remaining cognitive domains assessed in the CNS-Vital Signs battery. This may suggest that the VR-based cognitive training program may hold a limited effect on other specific cognitive functions, such as processing speed, executive function, and verbal memory. However, previous meta-analyses reported no positive effects on memory [40–42], execution function[40], and attention[40, 42] among patients with MCI.
The heterogeneity of the study designs, target groups (healthy older adults vs MCI and dementia), and outcome measures may contribute to the observed discrepancies.
The lack of significant effects on remaining cognitive domains may be attributed to various factors, such as individual differences in baseline cognitive abilities, the duration and intensity of the intervention, and potential ceiling effects. The current study delivered the interventions at least three times per week for 12 minutes per session for 12 weeks. This frequency and duration were chosen based on previous studies that have shown positive effects of VR interventions on cognitive function in older adults[43]. However, it is worth noting that the frequency and duration of VR-based cognitive interventions can vary considerably between studies. The duration of a single intervention ranged from 10 to 50 minutes[36, 44], the number of interventions ranged from 10 to 40 sessions, and the course of the intervention varied from 3 to 12 weeks[45]. These variations in frequency and duration highlight the lack of standardized guidelines for VR interventions in cognitive training. Future studies could explore these factors in more detail to better understand the mechanisms underlying the observed effects.
Despite heterogeneity in study populations and methodological differences in previous studies, our work provides further evidence to support the benefits of immersive VR cognitive training in eliciting improvements in visual memory, working memory and sustained attention among healthy older adults.
Limitations
The results of the present study contribute to the existing literature on the relationship between cognitive training and cognitive performance. The present study has several strengths, including the use of a randomized controlled design, a relatively large sample size, and objective measures of cognitive performance. However, there are also some limitations that should be considered. Firstly, the study sample consisted of healthy seniors, which may limit the generalizability of the findings to older adults with cognitive impairments or other health conditions. Future research could investigate the effects of VR-based cognitive training in more diverse populations. Secondly, the intervention duration of 12 weeks and intensity (at least three times per week, each session lasting for 12 minutes) may not have been sufficient to capture the full extent of cognitive improvements that could be achieved with longer-term interventions. Future studies could explore the effects of extended interventions on cognitive outcomes.