LEC 19: PTSD

What is Post-Traumatic Stress Disorder (PTSD)?

• a disorder where exposure to a traumatic or stressful event is listed explicitly as a diagnostic criterion

• clinical presentation varies; can be predominately fear/anxiety, anhedonic/dysphoric, arousal/reactive, or dissociative, or a combination

Diagnostic features of PTSD

• A. Confirmed experience of trauma

• B. Presence of intrusion symptoms

  • dissociative reactions (e.g. flashbacks)

• C. Persistent avoidance of stimuli associated with the event

• D. Negative alterations in cognitions and mood associated with the event

  • inability to remember details associated with trauma

• E. Marked alterations in arousal and reactivity associated with traumatic events, as evidenced by at least 2 of:

  • irritability

  • recklessness

  • hypervigilance

  • sleep disturbance

  • problems with concentration

  • exaggerated startle response

• Has to have significantly impacted psychological well-being for at least 1 month

Epidemiology of PTSD

• projected lifetime risk in Canada for PTSD is 9.2%

• PTSD is more prevalent among females than males across the lifespan, and experience PTSD for a longer duration

  • possibly due to greater exposure to sexual assault and other unwanted sexual experience

Neural basis of PTSD

• fear circuitry: traumatic events

  • amygdala hypersensitive

  • PFC activity reduced (ineffectively inhibits amygdala)

  • results in:

    • hypervigilance

    • intrusion symptoms

    • avoidance of stimuli

    • cognitive distortions

• significantly reduced volume of the hippocampus; ventral medial portion of the PFC (vmPFC)

  • meaning the hippocampus is not able to use contextual cues in the environment to signal safety

• reduced cortical capacity to inhibit fear

Functional anatomical differences and neurobiological difference of PTSD

Functional anatomical differences:

• exaggerated amygdala activation in response to trauma-related and generic stimuli.

• traumatic events serve as unconditioned stimuli, pairing with other stimuli (e.g., odors, sounds) to elicit fear responses and activate the amygdala.

Neurobiological differences:

• enhanced stress activation, both SAM and HPA pathways

• dysregulated signaling of noradrenaline considered biomarker of PTSD

Treatment of PTSD

• administration of propranolol (a beta-receptor antagonist) within hours following trauma exposure reduces likelihood of developing PTSD

  • prevents binding of noradrenaline

  • highly criticized

• cannabidiol (CBD) may effectively decrease symptoms