Dementia Symptoms: Your Sense of Smell
New research suggests that, with a decrease in your sense of smell, an increase in Alzheimer’s disease (AD) is possible, according to an article published in JAMA Neurology.
More specifically, a loss in your sense of smell may indicate the beginning of some types of dementia, researchers say. Anosmia, or loss of smell, has been marker for different types of dementia for some time. It already has been associated with cognitive decline, mild cognitive impairment (MCI)( or Alzheimer’s disease), a marker for Lewy body, and vascular dementia.
Knowing early markers of a condition are essential to preventing and delaying these diseases, and so understanding what make ensure from the loss of smell helps in identifying the condition and its risks.
Rosebud Roberts, of the Mayo Clinic in Rochester, MN, and coauthors assessed 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 participants were enrolled in the population-based, prospective Mayo Clinic Study of Aging between 2004 and 2010, and were clinically evaluated at baseline and every 15 months through 2014.
The researchers discovered that the loss of smell matches a loss in memory. Although not conclusive, the research of over an average of 3.5 years of follow-up provides strong evidence of the authors’ conclusion of the identified 250 new cases of MCI among the 1,430 participants.
The link between a decreased ability to identify smells were measured by a decrease in the number of correct answers in the smell test score – and an increased risk of amnestic MCI (aMCI). There appeared to be no association between a decreased sense of smell score and nonamnestic MCI (naMCI), which can affect other thinking skills.
The authors also found that of 221 with MCI, 64 had dementia. A decrease in the frequency of any or AD dementia was associated with increasing scores on the smell test. The worst smell test score categories were associated with progression from aMCI to AD dementia.
The findings suggest an association between olfactory impairment, incidental MCI, and progression from aMCI to AD dementia, and confirm previous studies linking olfactory impairment with cognitive impairment in late life.
There are neurodegenerative changes at the root of the symptoms. Some possible explanations for the current findings involve neurodegenerative changes in the olfactory bulb and brain regions that involve memory and sense of smell.
Remember about 10-20% of over-65s are estimated to have MCI and Alzheimer’s accounts for 60-80% of all dementias.
The olfactory bulb is believed to be involved because smell loss occurs only in neurodegenerative conditions where there is some sort of smell pathology, like AD and Parkinson’s disease.
The clinical implications for early detection of persons at risk of cognitive outcomes brings us closer to understanding dementia in its many symptoms so that we can better treat this condition.