Smell Test For Alzheimer's Disease: Can It Detect Risk Years Before Symptoms?

The idea that a simple smell test could help detect the risk of alzheimer's disease years before symptoms appear is gaining increasing attention in medical research. While memory loss is often the most recognised sign of the condition, scientists are now exploring whether subtle changes in the sense of smell could offer an earlier warning signal. According to Dr. Vinit Banga, Director and HOD- Neurology, Fortis Hospital Faridabad, "using a smell test for early detection of Alzheimer's disease is an idea that has been gaining popularity. Changes in the ability to smell may indicate the disease even years before memory problems begin."

Why Smell Matters for Brain Health

According to a study in Journal of the Neurological Sciences, people with alzheimer's disease may exhibit asymmetrical deficits in odour detection, with the left side more affected than the right. The sense of smell is closely linked to regions of the brain such as the hippocampus, which plays a key role in learning and memory. It is also connected to olfactory pathways that process different scents. "The sense of smell is directly associated with the hippocampus and olfactory areas. Problems with distinguishing between different odours can show up early in the development of alzheimer's disease," explains Dr. Banga.

This means that a decline in the ability to differentiate smells may reflect early changes in brain function, long before noticeable cognitive decline sets in.

What Studies Suggest

Growing scientific evidence supports this link. A study published in the journal Dovepress has shown that individuals who perform poorly on smell identification tests are at a higher risk of developing cognitive impairment later in life.

Also read: Alzheimer's Amyloid-Targeting Drugs Show No Clear Clinical Benefit: Review

These tests typically involve recognising common scents such as coffee, lemon, or rose. Difficulty in identifying these familiar smells may signal early neurological changes associated with Alzheimer's. Dr. Banga notes, "many studies have revealed that people with poor performance in odour tests are at higher risk of developing cognitive impairment. A reduced sense of smell can indicate the beginning of Alzheimer's many years in advance."

How Smell Tests Work

Smell tests are relatively simple and non-invasive. Participants are asked to smell a set of substances and identify them. Their responses are then scored and compared to age-based benchmarks.

Those who score lower may be considered at higher risk for neurodegenerative conditions. However, experts caution that this is not a standalone diagnostic tool. "Individuals who score low may have a greater chance of neurodegenerative diseases, but it is not conclusive evidence," says Dr. Banga.

Benefits of Smell Testing

One of the biggest advantages of smell tests is accessibility. They are easy to administer, cost-effective, and can even be conducted outside specialised hospital settings. This makes them a potentially useful screening tool, especially in large populations.

Early identification of at-risk individuals could allow for timely interventions, lifestyle modifications, and closer monitoring, all of which may help delay disease progression.

Limitations You Should Know

Despite their promise, smell tests are not foolproof. Several factors can influence a person's sense of smell, including ageing, smoking, sinus infections, and other neurological conditions. Because of this, experts stress that smell tests should not be used in isolation. Instead, they should be combined with other diagnostic approaches such as cognitive assessments, imaging studies, and clinical evaluations.

Dr. Banga highlights, "odour tests are not conclusive proof of alzheimer's. They should be used alongside other diagnostic tools like cognitive testing and brain scans."

A Step Towards Earlier Detection

Early detection remains one of the biggest challenges in alzheimer's care. By the time memory symptoms appear, significant brain changes may have already occurred. Tools like smell testing could help bridge this gap by identifying risk much earlier. While more research is needed to refine and standardise these tests, the current findings are encouraging. They open the door to simpler, more accessible ways of screening for one of the most complex neurological conditions. Smell tests are emerging as a promising early indicator of alzheimer's risk, offering a window into brain health years before traditional symptoms appear. However, they are not a definitive diagnostic tool.

Also read: Early Alzheimer's Detection Is Changing How Indian Families Plan Daily Life; Doctor Explains Shift

As Dr. Banga concludes, "smell tests can help identify individuals at risk before symptoms begin, but they must be combined with other methods for accurate diagnosis." In the future, something as simple as recognising a familiar scent could play a crucial role in protecting brain health and enabling earlier intervention against Alzheimer's disease.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.