Losing the sense of smell might be a precursor of Alzheimer’s disease

During a recent study, researchers found that elderly individuals who secured the worst scores in a smell test had 2.2 times greater chance of starting to have mild memory issues. Also, among elderly individuals who got the worst smell test scores and also had memory problems, the chances of developing full-scale Alzheimer’s disease were found to be significantly higher.

The study’s lead researcher Rosebud Roberts, who teaches neurology at the Mayo Clinic in Rochester, Minnesota, said that the findings of the study suggest that performing a smell test might assist in finding out whether an elderly, mentally normal individual is at risk of having memory issues as well as determining whether existing mental issues in a person have the chance of progressing to Alzheimer’s disease.

She added that doctors must recognize that smell test might be a screening tool which can be used in clinics. However, she didn’t forget to mention that these findings will not be applicable for individuals who always had problems with the smell as a result of having chronic respiratory tract disorders.

According to this new study, when dementia occurs and progresses, the parts of the brain responsible for our ability of distinguishing odors start deteriorating.

During the study, Roberts and her colleagues gathered data about health of over 1,400 mentally normal adults. The average age of these people was 79 years. After following up those individuals for an average period of three and half years, the researchers found that 250 of them developed memory issues (or mild cognitive impairment). Additionally, 64 out of the 221 individuals suffering from most severe memory issues developed dementia.


The smell test involved the use of 6 food-related and 6 nonfood-related smells; they are: chocolate, banana, lemon, onion, gasoline, cinnamon, pineapple, soap, turpentine, paint thinner, rose, and smoke. It was found that increase in those participants’ inability of identifying smells resulted in an increase in their chances of developing memory problems and Alzheimer’s disease.

However, researchers also made it clear that the association explained in the study didn’t establish a cause-n-effect relationship. Also, they also informed that they didn’t find any link between the decline in the sense of smell and other thinking disorders related to mild cognitive impairment.

The study has been published in the journal JAMA Neurology on November 16.