A new study proposed a causal link between loss of smell and Alzheimer's disease. The researchers noted a trend that those who lost their smell eventually developed dementia and then probably Alzheimer's disease.
The findings are based on the research conducted by Mayo Clinic research center in Minnesota involving 1430 volunteers with an average age of 79 years who were asked to undergo a standardized smell test. The participants were asked to determine 12 scents where half of these are food-related smells like cinnamon and banana, whereas the other half are non-food related including gasoline, rose petals and soap.
After three and a half years, the participants were traced, and researchers found that 250 of the volunteers have been manifesting mild cognitive impairment symptoms. Furthermore, 20 percent (64) of the 250 participants were pronounced with dementia, while almost 22 percent (54) with Alzheimer's.
Using these data, experts have come to conclusions that those who scored most badly and who scored weakest in the smell test both have an increased likelihood of suffering from dementia and Alzheimer's disease, respectively. "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," lead researcher Rosebud Roberts said.
The degeneration of the brain, as scientists suggest, affected the part responsible for the sense of smell concurring with the deterioration of the part controlling memory. "Clinical implications of our findings are that odour identification tests may have use for early detection of persons at risk of cognitive outcomes," study authors said.
Results of the study are, however, limited to the smell test alone and have no stronghold of the claim. In fact, several experts are not persuaded of the proposal as they claim of other several reasons to cause loss of smell.
However, the Alzheimer's Society considered the new research and stated that "If [the study is] used in combination with other tests it may help researchers to identify which of those already experiencing memory problems are at a greater risk of developing dementia, which could help in recruiting people to clinical trials to test potential treatments at a much earlier stage in the disease," said Alzheimer's Society director for research and development Dr. Doug Brown.
