A VR Game with Smell May Keep Cognitive Decline at Bay

Andrew Corselli

Experimental setup a) Laptop computer. b) Olfactory Display22. c) Meta Quest 3. d) Meta Touch Plus Controller. (Image: Nature.com/Scientific Reports)

One promising strategy to counter cognitive decline is through olfactory stimulation — engaging the sense of smell. Smell signals travel directly to brain regions involved in memory and emotion. Building on this knowledge, a joint research team from Institute of Science Tokyo (Science Tokyo), University of the Arts London, Bunkyo Gakuin University, and Hosei University, Japan, has developed the world’s first cognitive training method for older adults by combining olfactory stimulation with virtual reality (VR). The study was published in Volume 15 of the journal Scientific Reports.

“VR provides a promising platform to simulate sensory conditions in a controlled yet engaging manner. By combining goal-oriented tasks with real-time feedback, our VR-based olfactory training approach can increase cognitive engagement and maximize its therapeutic impact,” said Professor Takamichi Nakamoto, Science Tokyo.

The method involves an olfactory display that emits specific scents during immersive VR gameplay, activating memory- and emotion-related brain regions. In the activity, participants are asked to memorize and later match scents within a virtual environment. The experience begins in a virtual landscape. Using a VR controller, participants interact with a scent source represented by a stone statue. When touched, the statue releases a specific scent, accompanied by a white vapor cloud as a visual cue to reinforce memory.

Participants then explore the virtual landscape to locate a scent source. As they move through the landscape, the olfactory display emits subtle traces of the scent to guide them to the location. Upon reaching the odor source, shown as a stone lantern, they encounter three colored vapor clouds, each emitting a different scent. Their task is to compare the smells and identify the one that matches the original scent they memorized.

“The smell memory phase strengthens odor recognition and memory encoding by linking the olfactory stimulus with a visual cue. The navigation phase challenges players to integrate spatial navigation with odor recognition while retaining memory of the initial scent. The final odor comparison phase engages olfactory discrimination and working memory retrieval, reinforcing cognitive function,” explained Nakamoto.

The activity led to noticeable cognitive improvements in 30 older adults ages 63 to 90. After just 20 minutes of playing the VR game, participants showed improvements in visuospatial rotation and memory. Visuospatial processing and cognitive function were assessed through different tasks. In the Hiragana Rotation Task, where they had to decide if rotated Japanese characters matched the original, scores improved from 19–82 to 29–85. In a word-based spatial memory recall task, where participants memorized word positions in a grid, scores rose from 0–15 to 3–15. These improvements were validated through statistical analysis.

Screenshots of the contents. a) smell and memory initiation phase. b) Searching for the Odor Source and Maintaining Memory Phase. c) Comparison and Selection of the Smell Source Matching Memory Phase. (Image: Nature.com/Scientific Reports)

With continued research and development toward more affordable olfactory displays or alternate scent delivery methods, olfactory-based VR activities could become an accessible and engaging tool for supporting mental health in older adults.

Here is an exclusive Tech Briefs interview, edited for length and clarity, with Nakamoto.

Tech Briefs: What was the biggest technical challenge you faced while developing this cognitive training method for older adults?

Nakamoto: It took some time to fix the content of the cognitive test. Older adults can achieve full score if the test is easy. They have zero score if the test is too difficult. The appropriate test is necessary to observe the change of the cognitive test score.

Tech Briefs: Can you explain in simple terms how it works please?

Nakamoto: An older adult perceives olfactory stimulus from the game. In the VR game, he/she sniffs the scent and is requested to memorize it. Then, he/she approaches three scent sources and is requested to indicate which the memorized scent is. The scent is presented from an olfactory display, i.e., a smell presentation device that works synchronously with the VR game.

Tech Briefs: How does it differ from prior cognitive training methods?

Nakamoto: While traditional cognitive rehabilitation primarily relies on visual and auditory stimuli, incorporating olfactory input can enhance sensory integration and engagement by leveraging human cognition’s multimodal nature. VR-based cognitive training can better replicate everyday sensory experiences. This is especially true for olfactory stimuli.

Tech Briefs: The article I read says, “With continued research and development toward more affordable olfactory displays or alternate scent delivery methods, olfactory-based VR activities could become an accessible and engaging tool for supporting mental health in older adults.” My question is: Do you have any set plans for further research/work/etc.? If not, what are your next steps?

Nakamoto: We want to know how much olfaction contributes to cognitive rehabilitation in comparison with vision. Moreover, we plan to develop scalable olfactory VR solutions for real-world applications.

Tech Briefs: Is there anything else you’d like to add that I didn’t touch upon?

Nakamoto: Since we study olfactory VR, we will develop more sophisticated devices and contents, followed by their application to cognitive rehabilitation.

Tech Briefs: Do you have any advice for researchers aiming to bring their ideas to fruition (broadly speaking)?

Nakamoto: We form a team made up of VR people, psychologists and an artist. An interdisciplinary collaboration is very important to solve a real problem.