Alzheimer’s is a common progressive disease, a brain disorder that affects memory, behavior, and thinking. It begins with mild symptoms, including loss of smell, confusion with recent information, changes in vision, poor judgment, and social withdrawal.
Amongst all of these symptoms, the changes in the sense of smell are one of the potential indicators of the disease’s onset. Even before losing the sense of smell was strongly correlated to COVID-19, it was associated with a signal of inflammatory response in the brain. And in diseases like Alzheimer’s, inflammation is a part of the neurodegenerative process.
This article focuses on the connection between Alzheimer’s and loss of smell. Continue reading to learn more:
The Link Between Alzheimer’s And Sense Of Smell
Alzheimer’s is a neurodegenerative disorder that affects the memory and cognition regions of the brain. Although many indications/ symptoms are leading to this condition, a declining sense of smell is prominent.
Based on studies from researchers at the University of Chicago, a declining sense of smell around the age of 65 or more can be a sign of Alzheimer’s. The study involved over 800 people and their DNA samples to determine which individual carried the APOE e4 gene (associated with increased risk of Alzheimer’s).
As mentioned above, Alzheimer’s is a neurodegenerative disorder, and the initial signs of neuron degeneration appear in the brain’s olfactory cortex. It is the part that controls the sense of smell.
Our ability to the sense of smell begins from our noses’ mucus membranes. These membranes send electrical signals to the olfactory cortex in the brain through the olfactory nerve to process the scent. The same olfactory nerve is also responsible for sending signals to the amygdala and hippocampus, the section of the brain responsible for processing emotions and memory. It is also why certain smells/ scents can be associated with some memories.
Olfactory Dysfunction, An Early Indicator Of Alzheimer’s
Olfactory Dysfunction is when an individual experiences a disturbance or impairment in the sense of smell. It can be classified as changes in the perception of aromas, loss of smell sense, or a reduced ability to detect odors. While it is not fully understood why, some studies suggest that people with Alzheimer’s may commonly suffer from Olfactory dysfunction.
Although it isn’t a definitive diagnostic tool, the link between Olfactory dysfunction and the onset of Alzheimer’s cannot be denied. The Olfactory dysfunction can precede more noticeable cognitive symptoms in Alzheimer’s patients.
Individuals who notice a decline in their sense of smell and the ability to identify and discriminate odors may be at an early stage of Alzheimer’s.
It is also important to note that Beta-amyloid plaques, a characteristic of Alzheimer’s, can also accumulate in the olfactory areas of the brain, thus disrupting the functioning of olfactory neurons and resulting in changes in smell detection.
What Causes Smell Loss In Alzheimer’s Disease?
The interconnection between Alzheimer’s and smell loss also correlates to the presence of amyloid plaques and neurofibrillary tangles. The olfactory system’s vulnerability, coupled with its limited self-repair mechanisms, leads to more related damage.
Detection Of Alzheimer’s Through Odor Test
The correlation between olfactory dysfunction and Alzheimer’s has now prompted investigations into the feasibility of using smell tests as an early diagnosis method. The idea of an odor test can be a relatively simple and non-invasive screening tool for the risk of Alzheimer’s.
However, odor tests cannot be the standalone option, and combining them with clinical assessments, biomarkers, and neuroimaging is essential for enhancing the accuracy and reliability of the diagnosis.
Overall, Alzheimer’s disease, a progressive neurodegenerative disorder, manifests through various symptoms, with a declining sense of smell emerging as a potential early indicator. Research indicates that olfactory dysfunction, linked to the onset of Alzheimer’s, may precede noticeable cognitive symptoms.
The interplay between Alzheimer’s and the olfactory system, vulnerable to damage due to the limited self-repair mechanisms, underscores the significance of smell loss as a biomarker. Ongoing investigations into odor tests as a diagnostic tool offer a promising avenue for early detection. While it isn’t a standalone option, combining odor tests with other assessments provides a comprehensive approach to enhance accuracy in Alzheimer’s diagnosis and intervention.