Losing your sense of smell? It could be an early dementia warning, say scientists

Losing your sense of smell could be an early warning sign of something far more serious than a common cold. Scientists have now cracked why your sense of smell goes before memory problems kick in.

The Link Between Smell And Dementia

Struggling to smell your dinner or fresh flowers is often an early indicator of Alzheimer's disease. This symptom appears long before memory and cognitive functions take a hit.

Exactly what happens in the brain’s smell regions remained a mystery, until now. Researchers from DGIST and Maastricht University peered into the olfactory system at a cellular level.

Brain's "Firefighters" Act Differently

The team, led by Professor Moon Cheil, found immune cells in the brain act like 'tailored firefighters'. They respond differently depending on which part of the olfactory system is attacked.

In the olfactory cortex, astrocytes lead the immune response, while microglia take charge in the olfactory bulb. This specific insight could open doors for treatments targeting particular brain regions.

Prof. Moon explained: "This study is a significant achievement that explains at the systems level why the olfactory system is the first and most severely affected by Alzheimer’s disease."

Toxic Proteins And Early Clues

Toxic proteins, like amyloid beta and tau, are known culprits in Alzheimer's. These harmful proteins build up in the brain, slowly destroying nerve cells.

The study confirmed that these proteins accumulate first in the olfactory bulb and olfactory cortex. This happens rather than in other brain areas, aligning with earlier academic findings.

A Universal Early Warning

The research also flagged an increase in Apolipoprotein E (ApoE) aggregates in the olfactory systems of all patients. This was true regardless of carrying the APOE ε4 gene, a known strong genetic risk factor.

This finding suggests a universal early diagnostic marker for patients regardless of genetic background.

"The different immune cell-pathological networks identified in the olfactory bulb and olfactory cortex will serve as a crucial starting point for developing early diagnostic markers for Alzheimer’s disease and establishing region-specific treatment strategies," Prof. Moon added.

The findings, co-led by Ph.D. candidate Jeong Da-hye, were published in the April 2026 issue of Alzheimer’s & Dementia. Jeong Da-hye also received a "Young Investigator Award" in 2025 for her capabilities.

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OFFICIAL SOURCE VERIFICATION: This report is based on official data from University Newsroom. Document: [The Moment Scents Disappear, the Clock of Dementia Begins Ticking: DGIST Identifies the Cause of Olfactory Impairment for the First Time](https://www.asiaresearchnews.com/node/22658)