Loss of smell in later life could be an early indicator of dementia, according to a study published in the Journal of the American Geriatrics Society.

Researchers tested the sense of smell in nearly 3000 people aged 57 to 85 years of age and found that those who could not detect five different odours went on to develop dementia in the five year follow up period. The researchers, therefore, suggest that loss of smell could be an early sign that the brain is not functioning properly and could be a useful tool in predicting the onset of dementia.

In the study the 3000 participants were asked to detect the following odours – peppermint, fish, orange, rose and leather. Around 78 percent of participants had a normal sense of smell and could identify all 5 scents, with only 1 percent unable to identify any of the odours and 2.2% only able to identify 1 or 2. After a period of around 5 years, the researchers followed up on the tests subjects and found that almost all the people who could not identify one of the scents had developed dementia. In addition, of those who could only successfully identify 1 or 2 of the scents nearly 80 percent had developed dementia.

Smell is closely connected with brain function and losing your sense of smell could be an indication that something is wrong in the brain. However, there are many reasons why people lose their sense of smell, so on its own, it is not a clear indicator of dementia. The researchers suggest this could be an early sign indicating those who might be at risk of developing dementia and that people who have lost their sense of smell in later life may warrant further follow up tests. Early diagnosis of dementia can help to develop new treatments and preventative therapies.

Rachel Kayani