A smell test can help identify the risk of developing Alzheimer's disease early, latest research shows.
Of the four studies presented at the Alzheimer's Association International Conference in Copenhagen, two provided solid evidence to show a direct link between poor sense of smell and the brain disease, while the rest two found an eye test highly promising in measuring the amount of beta-amyloid, the toxic protein responsible for the disease present in the brain. The accumulation of beta-amyloids in the brain have long been known to damage and kill brain cells, causing memory problems associated with the disease.
In the first study on smell and Alzheimer's, a team of Harvard researchers looked at 215 normal elderly people. As a part of the study, the participants took a smell identification test developed by the University of Pennsylvania and some other tests that measured their cognitive ability. The researchers also measured the size of two brain structures related to memory skills called entorhinal cortex and the hippocampus in the participants, and also checked the presence of amyloid build up in their brain. Results showed direct links between smaller size of the brain structures, higher levels of amyloid build up, reduced ability to identify smells and higher memory problems.
"Our research suggests that there may be a role for smell identification testing in clinically normal, older individuals who are at risk for Alzheimer's disease," researcher Matthew E. Growdon, candidate at the Harvard Medical School and Harvard School of Public Health, said in a news release. "For example, it may prove useful to identify proper candidates for more expensive or invasive tests."
In the second study, researchers from the Columbia University Medical Center in the US studied 1,037 older people aged around 80. During the study, the participants took tests that measured their ability to identify smells. During the study, nearly 101 people developed Alzheimer's, another 109 were diagnosed with dementia and another 270 died. Researchers followed the rest 757 people and found an association between a lower odor identification score and the brain conditions.
Researchers said that a poor ability to identify odors signalled to loss of brain function and the onset of Alzheimer's disease as the brain cells that regulate sense of smell also get affected as the disease progress.
At present, there does not exist any proper diagnostic method to identify the condition early. Doctors diagnose it through symptoms and by testing thyroid disorder, vitamin deficiency, brain imaging and neuropsychological factors. The whole process can take lots of time as the clinical symptoms associated with the disease starts appearing only about 10 years after its onset. This can delay the treatment and also the possibilities of recovery. Though some brain scans and tests can help identify the presence of certain early biomarkers of the disease, they are too expensive and invasive.