Smell Tests Could One Day Reveal Head Trauma and Neurodegenerative Disease (Scientific American):
“Name that smell—if you can’t, it could be an indicator of a problem somewhere in your brain. New research suggests that scratch-and-sniff smell tests could become an easy and cheap way to detect signs of traumatic brain injury and neurodegenerative ailments.
Recent research found that a diminished sense of smell predicted frontal lobe damage in 231 soldiers who had suffered blast-related injuries on the battlefield…subjects with low scores on a smell test were three times as likely to show evidence of frontal lobe damage during brain imaging than those whose sense of smell was normal.
When the sense of smell is working properly, it acts as a matchmaker between odorant molecules in the air and memories stored in the brain. Those memories are not housed in a single place, Xydakis says, but extend across many regions. Because different smell signals have to take a variety of paths to reach their destinations, arranging their travel requires a lot of coordination. “This unique feature makes an individual’s ability to describe and verbally name an odor extremely challenging and cognitively demanding,” he says.”
Study: Olfactory impairment and traumatic brain injury in blast-injured combat troops (Neurology). From the abstract:
- Objective: To determine whether a structured and quantitative assessment of differential olfactory
performance—recognized between a blast-injured traumatic brain injury (TBI) group and a
demographically comparable blast-injured control group—can serve as a reliable antecedent
marker for preclinical detection of intracranial neurotrauma.
- Results: Olfactometric score predicted abnormal neuroimaging significantly better than chance
alone…Troops with radiographic evidence of frontal lobe injuries were 3 times more likely to have olfactory impairment than troops with injuries to other brain regions
- Conclusion: Quantitative identification olfactometry has limited sensitivity but high specificity as
a marker for detecting acute structural neuropathology from trauma. When considering whether
to order advanced neuroimaging, a functional disturbance with central olfactory impairment
should be regarded as an important tool to inform the decision process.