According to an article published in JAMA Neurology, a recent study found out that a certain decrease in the sense of smell appears to be associated with the early detection of dementia and Alzheimer's. Thus, previous researches have also linked olfactory loss or anosmia with cognitive decline, mild cognitive impairment (MCI) or Alzheimer's disease (AD), and may also be a marker for Lewy body and vascular dementia. 

Alzheimer's disease is a type of dementia that causes problems with memory, thinking and behavior. The symptoms of Alzheimer's usually develop slowly and get worse over time, eventually becoming severe enough to interfere with daily tasks. 

The Medical News Today report also includes that autopsy studies have linked a loss of ability to identify odors with the plaques and tangles in the olfactory bulb, entorhinal cortex and the cornu ammonis regions of the hippocampus.

Researchers believe that markers of early detection can help prevent or delay these diseases, and olfactory impairment may be an important clinical marker and predictor of these conditions, helping to identify those at risk.

Rosebud Roberts, of the Mayo Clinic in Rochester, Minnesota and her colleagues assessed that olfaction or the sense of smell of 1,430 cognitively normal individuals, with an average age of 79.5 years. Approximately, half were men and half were women.

"The findings suggest that doing a smell test may help identify elderly, mentally normal people who are likely to progress to develop memory problems or, if they have these problems, to progress to Alzheimer's dementia," Roberts explained. "Physicians need to recognize that this may be a possible screening tool that can be used in the clinic." 

In the test, there was an association between a decreasing ability to identify smells as measured by a decrease in the number of correct answers in the smell test score and an increased risk of amnestic MCI (aMCI). Thus, this link is believed to seriously affect daily lives and lead to impaired thinking skills as well as other issues on trouble planning or poor judgment.

The authors therefore concluded that clinical implications of their findings are that odor identification tests may have use for early detection of persons at risk of cognitive outcomes.