🌟 🧠 COGNITION FOCUS 🧠 🌟 

In the world of longevity medicine, one of the most important issues is maintaining excellent cognition. Many of the topics covered in these newsletters are relevant to that effort. I’m listing some here. I plan to eventually gather them, their “Quick Takes” and their “Favorite Finds” into a single actionable resource.

At the moment, some of these topics have Workbooks you can purchase, with or without a monthly subscription to the Simple Science resource site.

• The relevance of time-restricted eating to the gut microbiome

• How to optimize sleep (workbook)

• What your food should do for you (workbook)

• How we lose our ability to regulate glucose

• How we can improve our ability to regulate glucose

• Understanding and improving air quality

• Optimizing muscle (workbook)

• Understanding and improving measures of stress (HRV) (workbook)

• Improving the mouth microbiome

• Evaluating and reducing cardiovascular disease risk

• Purpose and Longevity (workbook)

• Olive Oil

• Improving Memory with Scent

😋 Quick Takes

👃 Smell Training Shows Dramatic Memory Benefits

Cognition is enhanced by spending time interacting with scents: memory games using tea bags, “scent training” with essential oils, and even diffusers used for brief periods.

👂️ Hearing Aids Reduce Fatigue, And Sometimes Cognitive Decline

The landmark ACHIEVE trial revealed that hearing aids significantly reduce fatigue in older adults but don't prevent cognitive decline in most people. Cognitive benefits were seen in individuals with depression or cardiovascular risk factors.

🔊 Noise Pollution May Accelerate Dementia

Danish studies found that exposure to road and railway traffic noise increases Alzheimer's disease risk, while chronic noise promotes brain lesions and DNA damage through multiple pathways including inflammation and stress hormone disruption.

👉️ Touch Sensitivity Declines with Age and Cognition

Finger sensitivity declines with age, while arm and cheek sensitivity remains preserved. In general all sensory functions decline in parallel with impairments in cognition.

🕊️ Multisensory Stimulation Improves Dementia Symptoms

A meta-analysis of 16 studies found that multisensory interventions significantly reduce agitation, apathy, and depression in dementia patients while improving overall cognitive function. Natural soundscapes and familiar music showed the strongest effects.

Favorite Finds

Snoezelen Rooms for Therapeutic Multisensory Experience

These specially designed environments combine controlled lighting, textures, sounds, and aromas to create calming, therapeutic spaces. Originally developed for individuals with developmental disabilities, they're now being adapted for dementia care and stress reduction.

VR Nature Experiences with Spatial Audio

Some virtual reality platforms combine visual immersion with 3D soundscapes featuring birdsong, water sounds, and wind. These tools can provide the benefits of natural soundscape therapy in any setting. I haven’t explored these but if you have any favorites, let me know!

Essential Oil Rotation Systems

You can purchase 5-7 essential oils, including rose attar, peppermint, sage, rosemary, and whatever else you like, and use them in various places: peppermint in the car, rose on your walks, lavender where you brush your teeth. Then spend time inhaling scents as you go about your day.
If you have a feline companion, you can try small airtight spice jars and recap them after use. Aromatherapy jewelry and other items are available on Etsy.

🌊 Deep Dive: The Multisensory Brain

The Scent of Memory: Olfactory Pathways to Cognitive Enhancement

The olfactory system holds a unique position—it's the only sense with direct projections to the limbic system, bypassing the brain's usual relay station, the thalamus (Leon & Woo, 2022; Woo et al., 2023). This direct access to memory and emotion centers may explain why smell-based interventions show the most remarkable cognitive benefits.

Minimal olfactory enrichment can produce dramatic results. Older adults who used essential oil diffusers for just 2 hours each night, rotating through 7 different scents, showed a 226% improvement in memory performance compared to controls (Woo et al., 2023). Brain imaging revealed that this simple intervention strengthened the uncinate fasciculus, a crucial neural pathway that typically deteriorates with aging and Alzheimer's disease.

The "Mind Your Nose" study further demonstrated that active olfactory training—playing scent-matching memory games for 20 days—improved not only smell-related tasks but also untrained visual memory, suggesting that olfactory training enhances general cognitive abilities (Burke et al., 2025). Systematic reviews confirm that olfactory training protocols involving 4 or more scents, used twice daily for 12-24 weeks, create positive neuroplastic changes including increased brain volume and enhanced connectivity (Vance et al., 2024).

Sound and Silence: The Complex Relationship Between Hearing and Cognition

While research consistently shows associations between hearing loss and cognitive decline, intervention studies reveal a more complex picture. The ACHIEVE trial—one of the largest randomized studies of hearing interventions—found that hearing aids reduce fatigue and improve quality of life, while cognitive benefits are seen in high-risk subgroups with depression or cardiovascular risk factors (Lin et al., 2023; Bessen et al., 2024).

However, the auditory environment's impact on brain health extends beyond hearing loss treatment. Chronic noise exposure appears to actively harm cognitive function through multiple mechanisms: reducing neurogenesis in memory centers, promoting inflammation, disrupting sleep and stress hormone systems, and potentially accelerating Alzheimer's-like brain changes (Dai et al., 2024; Belojević, 2024).

Conversely, therapeutic sound interventions show remarkable promise. Natural soundscapes featuring birdsong, water, and wind can reduce agitation and improve mood in dementia patients. Music therapy, when delivered by trained professionals, improves attention, verbal skills, and information processing while reducing anxiety and depression through enhanced neuroplasticity and dopamine release (Belojević, 2024).

Vision, Touch, and the Sensory Web

Vision and touch research reveals how sensory impairments create cascading effects on cognitive function. Visual impairment is associated with cognitive decline, but the relationship appears mediated through activities of daily living—vision loss affects daily functioning, and this functional impairment worsens cognitive decline (Zhou et al., 2025; Nagarajan et al., 2022).

Similarly, tactile sensitivity research shows that reduced touch perception is associated with mild cognitive impairment, with finger sensitivity particularly vulnerable to age-related decline (Löffler et al., 2024; Samain-Aupic et al., 2024). However, tactile training programs demonstrate that targeted fingertip manipulation tasks can improve sustained attention in healthy adults, suggesting therapeutic potential (Luo & Zhang, 2020).

The Power of Multisensory Integration

Perhaps the most promising findings come from multisensory intervention research. A comprehensive meta-analysis of 16 studies found that multisensory stimulation significantly reduces agitation, apathy, and depression in dementia patients while improving overall cognitive function (Octary et al., 2025).

The most successful interventions combined multiple sensory modalities: comfortable environments with laser light projectors, instrumental music based on preferences, fragrance sprays, massage, and familiar poetry or stories. Sessions lasting 45-60 minutes repeated 20 times produced significant improvements in cognitive scores (Safavi et al., 2013).

Cognitive Stimulation Therapy, which integrates multiple sensory experiences, demonstrated significant improvements in general cognitive function and language skills, with medium effect sizes for verbal abilities (Calderone et al., 2025). These findings suggest that our brains benefit most from rich, varied sensory experiences rather than isolated sensory training.

Clinical Implications and Future Directions

The research reveals that our sensory systems are not independent channels but interconnected pathways that collectively shape brain health. Rather than seeking single sensory solutions, the future of sensory-based cognitive interventions lies in understanding and leveraging these complex relationships to create comprehensive approaches that support cognitive vitality throughout our lives. It is likely that other interventions, including regular exercise and a healthy diet also network with these sensory interventions to produce healthy aging.

References

Belojević, G. (2024). Sound and Alzheimer's disease-from harmful noise to beneficial soundscape augmentation and music therapy. Noise Health, 26(123), 445-448. doi: 10.4103/nah.nah_162_24

Bessen, S. Y., Zhang, W., Huang, A. R., Arnold, M., Burgard, S., Chisolm, T. H., Couper, D., Deal, J. A., Faucette, S. P., Goman, A. M., Glynn, N. W., Gmelin, T., Gravens-Mueller, L., Hayden, K. M., Mitchell, C. M., Pankow, J. S., Pike, J. R., Reed, N. S., Sanchez, V. A., Schrack, J. A., Sullivan, K. J., Coresh, J., Lin, F. R., Martinez-Amezcua, P.; ACHIEVE Collaborative Research Group. (2024). Effect of hearing intervention versus health education control on fatigue: A secondary analysis of the ACHIEVE study. J Gerontol A Biol Sci Med Sci, 79(11), glae193. doi: 10.1093/gerona/glae193

Burke, I. J. M., Chesser, C., Brown, C. P. K., Watkins, R., Butterworth, P., Olofsson, J. K., Laver, K., Hampstead, B. M., & Bahar-Fuchs, A. (2025). Mind your nose: A randomized controlled trial of olfactory-based memory training for older people with subjective cognitive decline. Alzheimers Dement (N Y).

Calderone, A., Marra, A., De Luca, R., Latella, D., Corallo, F., Quartarone, A., Tomaiuolo, F., & Calabrò, R. S. (2025). Multisensory stimulation in rehabilitation of dementia: A systematic review. Biomedicines.

Dai, X. J., Liao, J. H., Jia, Y., Cao, R., & Zhou, M. N. (2024). Noise exposure promotes Alzheimer's disease-like lesions and DNA damage. Noise Health, 26(122), 287-293. doi: 10.4103/nah.nah_26_24

Grenier, B., Berr, C., Goldberg, M., Jouven, X., Zins, M., Empana, J. P., & Lisan, Q. (2024). Hearing loss, hearing aids, and cognition. JAMA Netw Open, 7(10), e2436723. doi: 10.1001/jamanetworkopen.2024.36723

Leon, M., & Woo, C. C. (2022). Olfactory loss is a predisposing factor for depression, while olfactory enrichment is an effective treatment for depression. Front Neurosci.

Lin, F. R., Pike, J. R., Albert, M. S., et al.; ACHIEVE Collaborative Research Group. (2023). Hearing intervention versus health education control to reduce cognitive decline in older adults with hearing loss in the USA (ACHIEVE): a multicentre, randomised controlled trial. Lancet.

Löffler, A., Beier, F., Bekrater-Bodmann, R., Hausner, L., Desch, S., Silvoni, S., Kleinböhl, D., Löffler, M., Nees, F., Frölich, L., & Flor, H. (2024). Reduced tactile sensitivity is associated with mild cognitive impairment. EBioMedicine.

Luo, Y., & Zhang, J. (2020). The effect of tactile training on sustained attention in young adults. Brain Sci.

Nagarajan, N., Assi, L., Varadaraj, V., Motaghi, M., Sun, Y., Couser, E., Ehrlich, J. R., Whitson, H., & Swenor, B. K. (2022). Vision impairment and cognitive decline among older adults: a systematic review. BMJ Open, 12(1), e047929. doi: 10.1136/bmjopen-2020-047929

Octary, T., Fajarini, M., Arifin, H., Chen, R., Sung, C. M., Chang, L. F., Wang, C. H., Banda, K. J., & Chou, K. R. (2025). Multisensory stimulation reduces neuropsychiatric symptoms and enhances cognitive function in older adults with dementia: A meta-analysis of randomized controlled trials. J Prev Alzheimers Dis.

Safavi, M., Yahyavi, S. H., Farahani, H., Mahmoudi, N., & Mahboubinia, M. (2013). The effect of multi-sensory stimulation (MSS) on cognitive status of women with Alzheimer's disease in Fereshtegan elderly care center. J Jahrom Univ Med Sci.

Samain-Aupic, L., Dione, M., Ribot-Ciscar, E., Ackerley, R., & Aimonetti, J. M. (2024). Relations between tactile sensitivity of the finger, arm, and cheek skin over the lifespan showing decline only on the finger. Front Aging Neurosci.

Vance, D. E., Del Bene, V. A., Kamath, V., Frank, J. S., Billings, R., Cho, D. Y., Byun, J. Y., Jacob, A., Anderson, J. N., Visscher, K., Triebel, K., Martin, K. M., Li, W., Puga, F., & Fazeli, P. L. (2024). Does olfactory training improve brain function and cognition? A systematic review. Neuropsychol Rev, 34(1), 155-191. doi: 10.1007/s11065-022-09573-0

Woo, C. C., Miranda, B., Sathishkumar, M., Dehkordi-Vakil, F., Yassa, M. A., & Leon, M. (2023). Overnight olfactory enrichment using an odorant diffuser improves memory and modifies the uncinate fasciculus in older adults. Front Neurosci.

Zhou, C., Yang, G., Theeboom, M., Yang, H., Zhu, R., Zhou, Z., & Zhu, D. (2025). Role of visual function and performance of activities of daily living in cognitive function in patients with mild cognitive impairment: a cross-sectional study. Front Aging Neurosci.