Next: Smell tests to help detect brain injury and neurodegenerative ailments

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.

Learn more:

• What are cog­ni­tive abil­i­ties, and how to boost them