A virtual reality game integrating smell to fight cognitive decline

As the global population ages, supporting older adults in maintaining their cognitive and memory functions has become a pressing concern. The United Nations estimates that by the 2070s, there will be over 2.2 billion people aged 65 or older, surpassing the global number of children under 18. This demographic shift is especially pronounced in Japan, the fastest-aging country, where 28.7% of the population is 65 or older.

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 on March 28, 2025.

“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,” says Professor Takamichi Nakamoto from 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,” explains Nakamoto.

The activity led to noticeable cognitive improvements in 30 older adults aged 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.

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.

About Institute of Science Tokyo (Science Tokyo)

Institute of Science Tokyo (Science Tokyo) was established on October 1, 2024, following the merger between Tokyo Medical and Dental University (TMDU) and Tokyo Institute of Technology (Tokyo Tech), with the mission of “Advancing science and human wellbeing to create value for and with society.”

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