Researchers have discovered that a simple sniff test, when combined with brief cognitive exams, can help predict a low likelihood of developing Alzheimer’s.
Scientists have known for years that the olfactory bulb, responsible for transmitting smell information from the nose to the brain, is one of the first areas of the brain to be affected by Alzheimer’s disease. That’s why people with early-stage Alzheimer’s often lose the ability to distinguish odors before memory symptoms get noticed.
A new study from Columbia University Irving Medical Center has found that performing well on a sniff test can help predict which patients with mild cognitive impairment will develop Alzheimer’s. While clinicians currently use cognitive exams to screen for dementia, patients with mild cognitive impairment often follow up with difficult and costly diagnostic procedures. However, combining a simple cognitive screening with the odor test was highly predictive of which individuals developed Alzheimer’s later on.
"No one has looked previously at whether performing well on both the odor identification test and global cognitive performance tests is better at predicting a low risk of cognitive decline or development of Alzheimer's disease," says D. P. Devanand, MBBS, MD, lead author of the paper, professor of psychiatry at Columbia University Vagelos College of Physicians and Surgeons, and research psychiatrist at the New York State Psychiatric Institute. "If we could accurately identify individuals who are unlikely to experience cognitive decline and Alzheimer's disease, we would reduce the need for unnecessary diagnostic investigation with PET imaging and lumbar puncture, which can be cumbersome and expensive, and improve selection of patients for clinical trials, including possibly prevention trials."
Participants in the study had mild cognitive impairment without dementia. The 749 older adults finished a brief cognitive screening test and a smell identification test of 40 items. Follow-up occurred over a four-year period when they were monitored for a diagnosis of Alzheimer’s or other dementias. During that time, 109 individuals were diagnosed with a dementia, mostly Alzheimer’s.