Changes in Smell as an Early Dementia Sign
Our sense of smell does more than help us enjoy food or detect danger. It connects directly to brain areas that handle memory and emotions. When smell starts to fade, it might signal trouble brewing in the brain long before forgetfulness shows up. This change can be an early clue for dementia, including Alzheimer’s disease, the most common type.
Smell loss often happens years before other dementia symptoms appear. The olfactory bulb, a small spot near the nose, sends smell signals straight to memory centers like the hippocampus. In Alzheimer’s, damage might start in a brain stem area called the locus coeruleus, which links smells to feelings. When this link breaks, smell problems pop up first, acting as a warning that brain changes have begun.[1][3]
Experts know smell trouble is common in neurodegenerative diseases. It shows up in early stages of mild cognitive impairment, sometimes with slight movement changes. Studies confirm it predicts future cognitive decline and ties to over 139 brain conditions, including dementia.[2][3][6] Unlike memory loss, which people notice later, smell fades quietly and often goes unreported.
Not every smell loss means dementia. Aging naturally dulls smell after age 60. Colds, allergies, sinus issues, medications, smoking, or head injuries can cause it too. But if it lingers without a clear reason, it deserves a check, especially with other signs like confusion or mood shifts.[5]
Doctors use smell tests to spot issues early. Simple ones involve identifying scents, helping tell dementia from other problems. New tests like SMELL-S and SMELL-R aim to be reliable worldwide, even for those with varying smell sensitivity.[3] These could predict how fast dementia progresses.
The good news is smell training might help. Sniffing different scents twice a day for months can retrain the brain. Research shows exposing people to varied smells at night boosts memory by over 200 percent in older adults. This works because smell stimulates the hippocampus, the brain spot hit early by dementia. Even if smell is weak, regular scents can wake up the nerves.[4][5][6]
Paying attention to smell changes could lead to earlier care. Spotting it soon might slow things down with lifestyle tweaks, like better sleep, diet, or quitting smoke.
Sources
https://www.the-independent.com/life-style/health-and-families/parkinsons-alzheimers-symptom-disease-smell-b2893736.html
https://www.417integrativemedicine.com/articles/early-signs-of-mild-cognitive-impairment-and-functional-approaches-for-slowing-progression
https://www.pnas.org/doi/10.1073/pnas.1711415114
https://www.silverado.com/resident-life/amenities/memory-air-brain-wellness-system/
https://www.mayoclinic.org/healthy-lifestyle/healthy-aging/expert-answers/loss-of-taste-and-smell/faq-20058455
https://www.popularmechanics.com/science/health/a69851842/smell-boost-memory-study/
https://www.youtube.com/shorts/MRxvg7MxDik
