Loss of Smell After Concussion: The Overlooked Brain Vital Sign

After a concussion, we ask about headaches, dizziness, memory, balance, screens, and brain fog. But there is another question we may not ask often enough: has your sense of smell changed? Loss of smell can occur after concussion and traumatic brain injury, yet olfactory function often receives far less attention than vision, balance, or cognition.

In Episode 71 of Life After Impact, I spoke with neuroscientist Dr. Michael Leon and Super Senses founder Datar Sahi about smell, sensory testing, repetitive head impacts, olfactory enrichment, and why this quietly powerful sense may offer another window into brain health.

Why Can a Concussion Affect Your Sense of Smell?

Smell begins with specialized sensory neurons high inside the nasal cavity. Those neurons send information through tiny openings in the skull to the olfactory bulb and then onward into a network with close ties to memory and emotion. That is why the smell of rain, fresh-cut grass, a particular perfume, or a familiar kitchen can evoke a memory before you have consciously named the scent.

That same system can be vulnerable to head trauma. Olfactory dysfunction has been observed after concussion and traumatic brain injury, as well as in people exposed to repetitive head impacts. A change in smell does not diagnose a concussion, but it may be another meaningful piece of the neurological picture.

You May Not Realize Your Sense of Smell Has Changed

A complete loss of smell is hard to miss. But what if olfactory function drops by 20 or 30 percent? Most of us are not very good at noticing the absence of sensory information. Food may gradually seem less flavorful, you may add more seasoning, or familiar scents may simply seem weaker.

After a concussion, subtle sensory changes can be especially easy to overlook because headaches, fatigue, dizziness, sleep disruption, and cognitive symptoms are already competing for attention. That raises an important question: rather than asking whether smell seems normal, what if we measured it?

What If Smell Were Treated Like a Neurological Vital Sign?

In preseason concussion testing, clinicians may establish baseline measures of cognition, balance, or other aspects of neurological performance. If an injury occurs, there is something to compare against. The same principle could potentially be applied to sensory function.

The important distinction is that an objective change in olfactory function would not be a stand-alone concussion diagnosis. It could, however, provide another signal that the nervous system has changed and deserves a more complete clinical evaluation.

It's Not Just Smell

Smell is one part of a larger sensory-health conversation. The brain is constantly receiving and processing input through smell, taste, vision, hearing, and touch. We spend a great deal of time measuring outputs from the brain—memory, reaction time, speech, movement, and balance—but sensory inputs are also fundamental to how the brain understands the world.

Concussion rehabilitation already recognizes the importance of visual, vestibular, auditory, and cervical sensory systems. Smell and taste may receive less attention not because they are less neurological, but because they are less routinely measured.

What the NFL Has to Do With Smell

Professional football offers a compelling lens because players may accumulate years of repetitive head impacts, even when every individual impact does not lead to a diagnosed concussion. In our conversation, Dr. Leon discussed olfactory function in relation to repetitive head impacts and work involving current and former professional football players.

The question extends well beyond football. Soccer, hockey, lacrosse, rugby, combat sports, and other activities involving repetitive head impacts raise similar questions: could a measurable change in smell offer another clue about how the brain has been affected over time?

Smell, Cognitive Function, and Long-Term Brain Health

Olfactory pathways connect closely with regions involved in memory and emotion. Changes in smell have been observed in multiple neurological conditions, which is one reason they should not be dismissed after head trauma. At the same time, reduced smell does not mean someone is developing CTE, Alzheimer's disease, or Parkinson's disease. Viral illness, nasal and sinus conditions, medication effects, aging, and head trauma can all affect olfaction.

The practical takeaway is not fear—it is curiosity. When a sensory change is measurable, it may provide useful information that warrants appropriate evaluation rather than being treated as an unimportant symptom.

Can You Retrain Your Sense of Smell After Concussion?

Dr. Leon has spent decades studying olfactory enrichment, sometimes called olfactory training. The basic concept is repeated exposure to a variety of distinct, pleasant odors over time—sensory exercise for the olfactory system. The emphasis is not necessarily on one “perfect” scent, but on varied and meaningful stimulation.

Research discussed in the episode has explored olfactory enrichment in relation to cognitive function, sleep, and brain changes. This is an emerging area, particularly for concussion, and it is not an established cure for post-concussion symptoms. Still, the possibility that olfactory stimulation could become another tool in neurological rehabilitation is fascinating.

The broader neurorehabilitation principle may be familiar: the nervous system responds to appropriately dosed, varied, and meaningful stimulation. Olfaction may be another avenue through which we can provide it.

Smell, Sleep, and Mood After Concussion

The conversation also touched on sleep and mood—two areas that are deeply relevant to concussion recovery. Dr. Leon discussed the practical advantage of automated nighttime olfactory enrichment: a rehabilitation strategy is more likely to help if someone can actually follow it. His team's Memory Air device delivers rotating pleasant scents while a person sleeps.

Olfactory pathways also connect with brain regions involved in emotion. That does not mean smell loss causes every case of depression or anxiety after concussion. It is a reminder, however, that sensory function, cognition, sleep, and emotional health are interconnected parts of the same nervous system.

What Should You Do If Your Smell Changed After a Concussion?

First, do not ignore it. A change in smell after head trauma is worth discussing with a qualified healthcare provider. Depending on the situation, evaluation may involve clinicians with expertise in concussion, neurology, or ear, nose, and throat disorders.

Instead of relying only on “I think my smell is okay,” objective testing may offer a more useful picture of whether olfactory function has changed—especially if there is a prior baseline for comparison. The more objectively we can identify what has changed, the less likely we are to miss important pieces of the concussion puzzle.

This article is educational and is not a substitute for individualized medical advice. If you experience new, persistent, worsening, or safety-affecting symptoms after a head injury, seek evaluation from an appropriately qualified healthcare professional.