Cortisol Suppression and Startle Responses in Posttraumatic Stress Disorder (PTSD)
Condition: Post Traumatic Stress Disorder
MeSH terms: Stress Disorders, Traumatic; Stress Disorders, Post-Traumatic
Study type: Interventional

Summary: 
      Posttraumatic stress disorder (PTSD) occurs in some people after exposure to events that
      cause extreme fear or helplessness. The incidence of war zones worldwide and the prevalence
      of violence in large cities in the U.S., increases the likelihood that people will experience
      a traumatizing event in their lifetime. About 1 in 10 people who survive such events will
      develop PTSD, while most people will get better over time. This suggests that some people may
      have biological vulnerabilities that make it harder for them to recover. One of these
      biological risk factors may be related to how stress hormones work in people who get sick.
      Another is how people react to things that make them afraid or nervous, investigators have
      found that PTSD patients have higher than normal fear reactions. The part of the brain that
      reacts to fearful stimulation is linked to stress hormones; the purpose of this study is to
      examine how these systems interact. The study will suppress stress hormones (cortisol)
      production in one group of participants, while another will get a placebo. When their
      cortisol is suppressed, the participants will undergo a startle study to see if their fear
      responses are decreased. Investigators expect that people PTSD will show a normal fear
      response when their cortisol levels are reduced, similar to people without PTSD. This
      research can help discover new medicines for people with PTSD.
    

Detailed description: 
      The proposed study will provide innovative tools to tease apart the relationship between
      amygdala-dependent neurophysiology and HPA-axis sensitivity in a human clinical population.
      Investigators have discovered that cortisol suppression reduces fear responses in PTSD
      coupled with the development of new fear conditioning paradigms, providing a unique
      opportunity to interrogate amygdala-HPA interactions to determine aspects of the
      neurobiological underpinnings of PTSD-related pathology.

      Aim 1a will examine baseline and fear-potentiated startle (FPS) response, as well as
      cognitive awareness in PTSD patients and traumatized Non-PTSD controls during a fear
      conditioning experiment 10 hours after dexamethasone administration in a double-blind,
      placebo controlled crossover design.

      Aim 1b will examine the above outcome measures in PTSD patients and controls during a fear
      conditioning experiment 1 hour after dexamethasone administration in order to control for
      direct effects of dexamethasone.

      Aim 2a will examine fear-potentiated startle (FPS) response in PTSD patients and traumatized
      Non-PTSD controls during fear extinction, when the fear is acquired 10 hours after
      dexamethasone administration in a double-blind, placebo controlled crossover design.

      Aim 2b will examine the same outcome measures in PTSD patients and controls, when the fear is
      acquired 1 hour after dexamethasone administration in order to control for direct effects of
      dexamethasone.
    

Intervention name(s): Dexamethasone; Placebo
Intervention type(s): Drug; Drug
Intervention description(s): One tablet of 0.5 mg dexamethasone will be taken ten hours prior to completing study assessments.; One placebo tablet will be taken ten hours prior to completing study assessments.
Intervention MeSH terms: Dexamethasone
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: startle response; fear conditioning; PTSD