Acoustic Startle: Experimental PTSD Assessment Tool to be Studied in WI

The Wisconsin State Journal explores a new, experimental tool that researchers at Madison's Veterans Hospital are currently testing to gauge the effectiveness of posttraumatic stress disorder treatments. Called acoustic startle, the study will monitor eye flinch reactions, heart rate, and sweat production to sudden, loud sound to determine how severe the patient's PTSD is.

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From the Wisconsin State Journal:

Doctors at the Veterans Hospital are preparing for a new generation of veterans returning from Iraq and Afghanistan who might develop PTSD. They are researching new therapies for the disease that might make the condition more manageable for newly returned soldiers than it has been for many Vietnam veterans. The doctors are also looking at a new way of assessing the effectiveness of PTSD treatment.

The experimental assessment tool, called acoustic startle, is based on the flinch of a patient's eye muscles. It's a reflex to a sudden sound that can be measured by the contraction of the obicularis oculi, the muscle that gives people of a certain age bags under their eyes.

As with most psychological disorders, doctors now use questionnaires to rate symptoms of PTSD and determine whether medications or psychotherapies help patients get better. But sufferers of PTSD, many of them men who have been in combat, can be reluctant to acknowledge their symptoms, doctors say. Improvements in irritability, detachment, nightmares and flashbacks can be subtle.

In a study about to begin at the VA, electrodes will be placed below the eyes and on the arms and hands of veterans with and without PTSD. The subjects will wear headphones through which piercing tones will randomly ring. During 10-minute sessions of loud beeps, their eye muscle contraction, along with heart rate and production of sweat, will be measured. Some participants will have recently started detox for alcohol abuse.

The goal is to see if acoustic startle is a useful way of quantifying the severity of PTSD - and to learn if some patients, likely those who react most to sudden noise, "self-medicate" by drinking.

More clinical information on startle response from the National Center for PTSD:

Historical and contemporary records provide evidence that an important symptom seen in combat veterans diagnosed with Shell Shock, Combat Fatigue or Post Traumatic Stress Disorder has been, and continues to be, an exaggerated startle reflex. (6-9) Clinical observations of exaggerated startle in distressed combat veterans were so common by mid-century, some psychiatric authorities argued that increased startle was cardinal symptom of combat fatigue (10). While not considered the cardinal symptom of PTSD today, exaggerated startle remains tightly linked to trauma related psychological illness. In fact, according to DSM-IV, PTSD is now the only anxiety disorder in which hyperstartle is listed as a core symptom.

Investigators have had various motivations for studying the acoustic startle reflex in humans and especially in those suffering from PTSD. Some have been interested in finding out whether or not exaggerated startle is a marker (or sign) indicating, or helping to provide a reliable diagnosis of PTSD. The idea of an objective test for PTSD remains extraordinarily appealing to many clinicians and forensic specialists. It is felt that such a test would enhance discrimination between individuals who do and who do not have PTSD.

For other investigators, startle has been less interesting as test for PTSD, and more interesting as a probe in examining central nervous system reactivity in individuals with PTSD. Because so much is known about the neuroanatomical pathways of, and neurotransmitters involved in the startle reflex, several studies have used startle to gain an understanding of neurohormonal functioning in PTSD. Finally, several investigators have used startle as an objective measure of the emotional states of anxiety and fear and have used startle as a tool to elucidate the neural mechanisms involved in the learning and extinction of fear and anxiety.

The startle reflex is one that is shared by very nearly all animals. In basic terms, it is the rapid motor twitch or jump that occurs when an animal or human is exposed to a sudden stimulus (such as a touch, a noise, or a visual image or light). The term acoustic startle reflex refers to the startle response to loud or sudden sounds. In humans, the most consistent and easy way to measure the acoustic startle reflex is to record the speed and intensity of the eye-blink that occurs after someone hears the noise.

The Madison Veterans Hospital is also conducting other PTSD experiments, including:

"Imagery rehearsal therapy" to reduce nightmares - and, sometimes, other symptoms. "You practice a dream and change the ending," said researcher Tracey Smith.

The short-term use of steroids to boost cortisol, a stress hormone. Some patients with PTSD have low levels of cortisol, perhaps because a sudden rush of it following a traumatic event has blunted production. A two-week dose of steroids "could help normalize that system," said researcher Catherine Johnson.

Use of the drugs risperidone and quetiapine, both antipsychotics developed for schizophrenia, in addition to the antidepressants typically given to patients with PTSD.

Researchers are also testing the use of prazosin, a blood pressure medication that slows down the sympathetic nervous system, commonly known as the "fight or flight" response to danger.

Great to see these studies moving forward.