Loss of Smell May Signal Risk of Dementia Later in Life [Video]

  • Research about dementia continues to discover more information about early warning signs and causes.
  • A study from the University of California at San Francisco reveals that the quality of our sense of smell (known as olfaction) may be associated to dementia risk.
  • The research also looked into the connection of the efficacy of other senses (like hearing and vision) to dementia but concluded that the association with smell was the most significant.

The connection between dementia and the sense of smell.

The UCSF study followed almost 1,800 participants in the course of over 10 years. The researchers discovered that having a consistent strong sense of smell was linked with less risk of dementia onset. The scientists also considered the relationship between the efficacy of other senses (including hearing and vision) and dementia but concluded that the association with smell was the strongest.

All participants were dementia-free when the study started, but by the end about 18% (328 people) had developed the disorder. Of that group, only 83 still had a “good” sense of smell, versus 141 who had a poor sense of smell.

The study used scents like roses and lemons to assess the participants’ sense of smell. Even a small percentage (10%) decline in olfaction increased the risk of dementia by 19%.

The study may have detected a relationship between these factors, but it did not conclude how they are linked. What the scientists revealed is that the link may have to do with the specific areas of the brain that deteriorate with dementia.

“The olfactory bulb, which is critical for smell, is affected fairly early on in the course of the disease,” explains Willa Brenowitz, Ph.D., the first author of the study. “It’s thought that smell may be a preclinical indicator of dementia, while hearing and vision may have more of a role in promoting dementia.”

Warning sign

The researchers suppose that the connection with smell may be a warning sign and noted that sensory impairment may actually play a role in the development of dementia after onset.

“Sensory impairments could be due to underlying neurodegeneration or the same disease processes as those affecting cognition, such as stroke,” says Brenowitz “Alternatively, sensory impairments, particularly hearing and vision, may accelerate cognitive decline, either directly impacting cognition or indirectly by increasing social isolation, poor mobility and adverse mental health.”

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The study also found that participants who showed a decline in multiple sensory functions were more likely to develop dementia.

“Even mild or moderate sensory impairments across multiple domains were associated with an increased risk of dementia,” explains senior author Kristine Yaffe, M.D., “indicating that people with poor multisensory function are a high-risk population that could be targeted prior to dementia onset for intervention.”

Other factors to consider

While these correlations contribute to the body of knowledge of potential precursors to cognitive decline, there are many other factors at play (which the study acknowledges), including the incidence of diabetes and cardiovascular disease of the participants and their overall health.

Since early diagnosis is one of the best ways to prevent further cognitive decline, research such as this one are vital for cataloging the wide varieties of potential risk indicators for dementia.

How to reduce your risk of dementia

When it comes to prevention, some foods and simple practices, like spending time with friends or regular exercise, may help stave off dementia.

Photo Credit: Shutterstock

1. Be physically active

2. Eat healthily

3. Don’t smoke

4. Drink less alcohol

5. Exercise your mind

6. Take control of your health

7. Get enough sleep

Source: Mind Body Green


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