Keith Kelsen’s The Scent Narrative: PTSD and Scent Trauma (Part 1)

PTSD sensitivity may be normalized with scent treatment. 

In all of our previous blogs, I have addressed the many ways that scent has impacted our lives.  However, in this blog, we are addressing something that is a plague on the modern world; Post Traumatic Stress Disorder or PTSD.  Science has recently uncovered that the associated cause and treatment could be found in the smell associated with the event; this phenomenon is being called “scent trauma”.

Hope for a PTSD cure.

Scent trauma makes sense when we consider that memory for odors associated with intense emotional experiences is often stronger than logic. Scent and odors are the most closely attached to effect than any other sensory experiences. Those suffering from PTSD can “re-experience” their original tormenting experience in a flash. That trigger can lead to grave consequences, or with treatment, hope for a cure.


“When aroma triggers recall, you are caught in a wave of emotion and evocation like no other.” –Dr. Rachel Hertz The Scent of Desire.

Research in this area has been very revealing.  We now know from returning veterans of foreign wars, survivors of plane crashes, and survivors of 9/11 in New York, for example, that there are scents associated with the trauma.  Even though these trauma-related scents have been noted by clinicians to be precipitants of traumatic memories, little work has been published.  That does not negate its validity and, in fact, calls for more study.

One such study done on 9/11 by the Monell Chemical Senses Center in Philadelphia was the distinctive odor that lingered in the Ground Zero area for months after the tragedy. Researchers Pam Dalton and George Preti exposed those with PTSD from the event and those who were not there to the scent.

“Dr. Dalton’s hypothesis that odors encountered at disaster sites or during traumatic events may have a lasting psychological effect on individuals who are traumatized,” Dr. Preti explained, “It was my job to try to identify what they were and, once we identified them, we can reconstitute them.” The actual scent of Ground Zero was “a complex and unique mixture of chemicals that smelled rubbery, bitter, and sweet at the same time.

Those who were near or at Ground Zero had a massively different reaction to the reconstituted scent than a control group in Philadelphia who had never been exposed to the scent. Dr. Dalton’s breakthrough work has been using a “synthetic odor bouquet” identical to the odors found at the World Trade Center, to help desensitize the victims. From rescue workers to office workers and residents, virtually anyone else who had experienced odor-mediated flashbacks could benefit from the treatment.

“You show them what’s at the root of their flashbacks,” Dr. Preti was quoted as saying. Hop, fully that knowledge will short circuit the smell-anxiety feedback mechanism. This is an ongoing and long-term study.

There’s more hope for scent treatment on the horizon.  For those who live with PTSD, according to researchers at McLean Hospital the largest psychiatric affiliate of Harvard Medical School. They have found that the sense of smell could one day play a prominent role in treatment. An overview of the study found that Scent can serve as a “potent contextual cue for memory formation and can also serve up cues to the olfactory flashbacks” (OFs).  Additionally, emotional conditioning with other scents can be used in the treatment.

PTSD Cues and Scent

In the recent study, Extinction Reverses Olfactory Fear Conditioned Increases in Neuron Number and Glomerular Size the researchers found a direct link to trauma cues and the olfactory system both biologically and structurally. This first of its kind study states that it’s possible for fear behaviors associated with emotional learning to be reversed through exposure-based talk therapy.

“The olfactory system is often an underappreciated sensory system in humans, even though we’ve all experienced the feeling of smelling a particular odor and having an almost instant flashback or emotional experience of an old memory,” commented Dr. Filomene G. Morrison, Postdoctoral Research Fellow at McLean Hospital/Harvard Medical School, the lead author of the paper in which this appeared. An emotional memory, like the smell of home cooking, can trigger feelings of comfort, while for those with PTSD, an odor associated with a traumatic experience can trigger a negative response and PTSD symptoms.”

This study helps explain why the molecular, genetic and Neurobiology connections to the olfactory system are so important. “It’s the only sensory system where we have the specific genetic tools that allow us to dissect how different odors in the environment activate different neural pathways. There’s a gene for receptor A versus a gene for receptor B, and we don’t have that level of specificity in any other sensory system.” according to paper co-author Kerry J. Ressler, MD, PhD, Chief Scientific Officer and Chief of the Division of Depression and Anxiety Disorders at McLean.  Dr. Ressler’s paper went on to say:

“In the olfactory system, the fact that there are these genes that encode the different receptor specificities gives us a powerful tool for using genetic approaches to understanding how the brain codes for the environment. One of the ways that the brain codes trauma is by increasing sensitivity to the trauma cues in the environment and these tools make it tractable to understand how trauma is encoded. Nothing has been done in this particular realm—one that looks at the structural changes of the brain—particularly of the specific sensory representations associated with fear or trauma and how they change with regard to extinction or recovery from fear”.

Dr. Ressler concluded:

“This is exciting because we can now understand that there’s a biological, structural representation in the brain of this trauma-related sensitivity that can be normalized with treatment. The study helps to provide a neurological explanation for the sensitivity that people with PTSD tend to have to environmental triggers. It also provides hope in suggesting that the brain changes that occur with trauma are, in fact, reversible with treatment.”

This breakthrough can deal with a scourge of our modern times, PTSD.  We can now understand the environmental triggers and there is hope that it is reversible!  The power of scent is worthy of more exploration.

Getting a better understanding of the exact mechanisms that are underlying these changes, will be critical,” said Dr. Morrison about the study.

While we can identify olfactory cues, researchers are not sure yet what type of therapies could be implemented. In Part 2 of this series, I will open more information of how this may be possible.



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