Amazing! Vegetative State Patients React to Odors, Researchers Reveal

A new study has found a sur­pris­ing way to assess if veg­e­ta­tive state patients have a chance of recov­ery. Researchers from South­ern Med­ical Uni­ver­si­ty in Chi­na say that patients who react to cer­tain odors are more like­ly to regain consciousness.

The researchers test­ed 28 patients in a veg­e­ta­tive state by expos­ing them to dif­fer­ent odors like vanil­la and decanoic acid. They used elec­troen­cephalo­gram (EEG) scans to mea­sure the patients’ brain activity. 

The results showed that patients who react­ed to the odors, by show­ing changes in their brain waves, were much more like­ly to recov­er with­in 3 months. Specif­i­cal­ly, 10 out of 16 odor respon­ders regained con­scious­ness, com­pared to only 2 out of 12 non-responders.

“Odor respons­es should be con­sid­ered signs of con­scious­ness,” the researchers wrote. “The odor response may help in the eval­u­a­tion of con­scious­ness and may con­tribute to ther­a­peu­tic orientation.”

Inter­est­ing­ly, even non-respon­ders showed some dis­tinct brain pat­terns. They had high­er theta wave activ­i­ty, indi­cat­ing drowsi­ness, and low­er alpha and beta waves, linked to alert­ness and thinking. 

How­ev­er, this was only seen with the vanil­la scent, sug­gest­ing pleas­ant odors may be more like­ly to trig­ger a response in veg­e­ta­tive state patients.

“Theta con­nec­tiv­i­ty may be a neur­al cor­re­la­tion with olfac­to­ry con­scious­ness in patients with DoC, which could help in the eval­u­a­tion of con­scious­ness and con­tribute to ther­a­peu­tic strate­gies,” the researchers noted.

The olfac­to­ry sys­tem direct­ly con­nects to the fore­brain, bypass­ing the thal­a­mus which nor­mal­ly relays sig­nals to the con­scious parts of the brain. This may explain why odors can trig­ger respons­es even when a patient is oth­er­wise unresponsive. 

More research is still need­ed, but these find­ings pro­vide hope that sim­ple, non-inva­sive odor tests could help doc­tors deter­mine the best treat­ment options for patients with dis­or­ders of consciousness.

The results sug­gest that the abil­i­ty to process odors may be impaired in some veg­e­ta­tive states, and odor tests over time could pro­vide insight into a patient’s lev­el of recovery. 

Over­all, the researchers rec­om­mend fur­ther explor­ing the link between brain respons­es to pleas­ant odors and regain­ing con­scious­ness. With more data, odor tests show promise as a way to iden­ti­fy patients with the best chance of recovery.