Struggling to identify smells may signal Alzheimer’s disease, study finds

MONTREAL — Could your nose be a key to Alzheimer’s prevention? Being unable to tell distinctive smells from one another may foreshadow the onset of Alzheimer’s disease, a new study finds.

Researchers at McGill University in Montreal recruited 274 individuals, with a mean age of 63, for a study on how diminished olfactory ability could presage the onset of the neurological disease.

Woman smelling a flower
A new study finds that a person’s inability to distinguish distinctive scents from one another may signal the onset of Alzheimer’s disease.

Detection has long been a struggle for researchers, and once one starts developing symptoms it’s usually too late.

Participants, who were identified as being genetically at-risk for Alzheimer’s, were given scratch-and-sniff cards that had scents as varied as lemon, bubble gum, and gasoline.

One hundred participants also volunteered to have the cerebrospinal fluid (CSF) in their lumbar region tested, as the researchers sought to find the prevalence of Alzheimer’s-related proteins.

The researchers found that those at greatest risk of developing Alzheimer’s had the most difficulty distinguishing odors, which makes sense considering the olfactory bulb is one of the first regions of the brain to abandon Alzheimer’s sufferers.

“This is the first time that anyone has been able to show clearly that the loss of the ability to identify smells is correlated with biological markers indicating the advance of the disease,” says lead author Marie-Elyse Lafaille-Magnan in a news release.

While these findings could help hasten the discovery of the disease, it is important to note that the loss of ability to smell could also signal other medical conditions completely unrelated to Alzheimer’s.

Further inquiry must be made into how the devolution of smell correlates with the worsening of one’s mental state, the researchers conclude.

It is clear, however, that smell tests could play a vital role in early detection, and thus, more effective prevention.

“If we can delay the onset of symptoms by just five years, we should be able to reduce the prevalence and severity of these symptoms by more than 50%,” says co-author Dr. John Breitner, the director of the Centre for Studies on Prevention of Alzheimer’s Disease at McGill University.

The study’s findings were published in the journal Neurology.