Can a Diminished Sense of Smell Signal the Onset of Alzheimer’s Disease

Studies indicate a potential connection between Alzheimer’s disease and a decline in the sense of smell. Here’s an expert’s perspective on the matter.

Loss Of Sense Of Smell: An Early Sign Of Alzheimer’s?
Loss Of Sense Of Smell: An Early Sign Of Alzheimer’s?

Amidst the height of the COVID-19 pandemic, the loss of smell emerged as a prominent indicator of SARS-CoV-2 infection. For some individuals, this symptom persisted for weeks or even months, while others reported experiencing a distorted sense of smell, termed parosmia.

Interestingly, research published in the journal Neurology suggests that smell loss is not solely linked to COVID-19 but may also serve as a potential indicator of neurological issues such as Alzheimer’s disease.

What exactly is Alzheimer’s Disease

What exactly is Alzheimer's Disease

Alzheimer’s disease is a neurological condition characterized by a progressive decline in cognitive function. According to the World Health Organization (WHO), it is the most prevalent form of dementia, accounting for 60–70% of cases.

It’s estimated that nearly five crore individuals worldwide are affected by Alzheimer’s or related dementias, yet only one in four people with Alzheimer’s have received a diagnosis.

While Alzheimer’s can impact anyone, the risk increases with age, doubling every five years after the age of 65. Additionally, individuals with a family history of Alzheimer’s, those who have experienced head trauma, and individuals with Down syndrome are at a heightened risk of developing the disease.

Can Alzheimer’s disease cause a loss of the sense of smell

Can Alzheimer's disease cause a loss of the sense of smell

Dr. Kapil Agarwal, Senior Consultant and HOD-Neurology at Marengo Asia Hospital, Gurugram, explains that Alzheimer’s disease is characterized by progressive memory loss and cognitive decline, but it can also manifest non-cognitive symptoms such as anosmia, or loss of sense of smell.

According to a 2023 study published in the journal Neurology, researchers discovered that individuals with the APOE ε4 variant, who are at a higher risk of developing Alzheimer’s disease, experienced a decline in their ability to smell odors earlier than those without the variant. Interestingly, although the decline in smelling ability did not accelerate faster over time in the APOE ε4 group compared to others, it was observed that both the ability to recognize and name smells, as well as cognitive function, declined more rapidly with age in those with the APOE ε4 variant.

While the exact connection between Alzheimer’s disease and loss of smell remains incompletely understood, experts speculate that it may be related to damage in the frontal part of the brain. This region includes the olfactory bulb, which processes signals from the nose. Degeneration in this area due to Alzheimer’s disease could potentially disrupt these signals, leading to difficulties in perceiving smells accurately.

Symptoms of Alzheimer’s disease

Symptoms of Alzheimer's disease

In addition to a diminished sense of smell, several other symptoms can assist in detecting Alzheimer’s disease. These include:

1. Memory loss or struggles in recalling recently learned information, important dates, or events.
2. Repetition of questions or statements.
3. Challenges in planning and problem-solving.
4. Difficulty managing finances, following recipes, or keeping track of bills.
5. Confusion regarding place or time.
6. Getting lost or forgetting the method of travel.


Loss of sense of smell can serve as an early indicator of Alzheimer’s disease, according to research findings. Although the precise link remains unclear, it is suggested that it could be related to the degeneration of the anterior part of the brain, as explained by Dr. Agarwal.

While there is currently no cure for Alzheimer’s disease, there are medications available that can assist in managing cognitive symptoms and enhancing the quality of life for those affected. According to the doctor, these medications function by regulating neurotransmitters in the brain and may aid in slowing down the progression of symptoms. It is advisable to seek guidance from a healthcare provider to determine the most suitable treatment plan.