Two of the most pressing questions doctors can be asked after an unconscious patient with a brain injury comes into the hospital are, “Will they recover? What can we expect?” Despite all of the advances in modern science and imaging, it’s often still hard to tell if a patient is going to wake up or lapse into a coma.

The best answer that doctors could usually give in the past was, “Wait and see.” Now, however, a simple olfactory test that exposes patients to strong smells can help doctors make a better prediction. That, in turn, can inform treatment tactics and help patients recover faster and better in the long run.

Patients suffering from brain injuries are often knocked unconscious — but the level of unconsciousness varies dramatically from one person to another. Roughly four out of 10 people presumed to be totally unconscious actually have some level of awareness — even though they can’t communicate it.

However, human olfactory responses operate on a non-verbal level and are somewhat involuntary. Even when a patient is unconscious, strong smells can cause a visible reaction. Unpleasant odors often cause people to take short, abrupt sniffs of air. Mild, pleasant smells can provoke bigger sniffs. No sniff at all in response to strong odors can mean that the patient is likely in a vegetative state.

According to a new study, when a comatose patient “sniffs” in response to strong odors, there’s 100% they will regain consciousness after their brain injury. Among those that do not, 65% will never regain consciousness.

This is good news for brain injury victims and their families, as every piece of information helps. If your loved one suffered a brain injury due to another party’s negligence, find out what it takes to get the compensation you need for their care and future well-being.