New research presented at the 2016 Alzheimer’s Association International Conference (AAIC) suggests that there might be a link between cognitive impairments such as Alzheimer’s and the ability to detect and identify odors. This finding could provide the medical community with powerful new tests for detecting Alzheimer’s symptoms much earlier than is currently possible.
The data behind this announcement was published in January, but official press releases were saved until this year’s conference. According to an AAIC press release, this new test could help detect and halt the advance of the disease much earlier than current diagnostic methods:
Using other biomarkers of Alzheimer’s disease to detect the disease at an earlier stage - which have the potential to be lower-cost and non-invasive - could lead to dramatic improvements in early detection and management of the disease.
The smell test is known as UPSIT - the University of Pennsylvania Smell Identification Test. Test-takers are given forty different scratch-and-sniff samples to smell and are asked to identify each one through a series of multiple choice questions. The test is used in the detection of other cognitive impairments such as schizophrenia, brain tumors, and traumatic brain injuries.
Current indicator tests for Alzheimer's are conducted through collecting cerebrospinal fluid through spinal taps, or by measuring the thickness of the entorhinal cortex, the part of the brain that processes memory and one of the first areas of the brain to be affected by the disease. The new smell test is much less invasive (and painful) than spinal taps, and has been so far been much more efficient at detecting Alzheimer's than measuring the entorhinal cortex:
Our research showed that odor identification impairment, and to a lesser degree entorhinal cortical thickness, were predictors of the transition to dementia. These findings support odor identification as an early predictor, indirectly suggesting that impairment in odor identification may precede thinning in the entorhinal cortex in the early clinical stage of Alzheimer’s disease.
Test subjects with low UPSIT smell test scores were found to be more than three times as likely to have developed Alzheimer's or other cognitive impairments throughout the course of the trial. While several studies have shown evidence of a link between smell and cognitive impairment, the neural mechanism behind this link is still not fully understood.
As of today, there are still no known treatments to stop the progression of Alzheimer’s. Early detection remains one of the few ways to mitigate or slow the effects of cognitive impairment. Even though more research is needed before the smell test can be rolled out for use in clinical applications, researchers are hopeful that this test could help turn the course of the fight against this terrible brain-eating disease.