Heterogeneity of defensive responses after exposure to trauma: Blunted autonomic reactivity in response to startling sounds

Other studies employed the term 'active suppression' to reflect significant heart rate deceleration or reduced heart rate reactivity concurrent with parasympathetic dominance.

“Meanwhile, other studies employed the term ‘active suppression’ to reflect significant heart rate deceleration (D'Andrea et al., 2013) or reduced heart rate reactivity (Sack et al., 2012) concurrent with parasympathetic dominance (Lanius et al., 2018; Schauer & Elbert, 2010).”

In D'Andrea et al. (2013), participants who did not meet criteria for PTSD, had lower trauma exposure, and did not demonstrate state dissociation in response to startle showed decreased heart rate acceleration and skin conductance as the task continued along with stable heart rate deceleration.

“Conversely, participants who did not meet criteria for PTSD, had lower trauma exposure (e.g., later in life, single trauma) and who did not demonstrate state dissociation in response to startle showed decreased heart rate acceleration and skin conductance as the task continued along with stable heart rate deceleration.”

In D'Andrea et al. (2013), participants who reported state dissociation after startle, had a PTSD diagnosis, and varied exposure to trauma showed initial reduced heart rate acceleration and reduced skin conductance that remained low throughout the task, while also exhibiting decreasing heart rate deceleration with concomitant increasing heart rate acceleration as the task progressed.

“Specifically, participants who reported state dissociation after startle, had a PTSD diagnosis, and varied exposure to trauma, showed initial reduced heart rate acceleration and reduced skin conductance (that remained low throughout the task), while also exhibiting decreasing heart rate deceleration with concomitant increasing heart rate acceleration as the task progressed.”

Other studies found autonomic responses in PTSD patients to be either physiologically similar to controls or reduced from baseline.

“Other studies found autonomic responses in PTSD patients to be either physiologically similar to controls or reduced from baseline (Cuthbert et al., 2003; D'Andrea et al., 2013; Limberg et al., 2011; McTeague & Lang, 2012).”

A subset of traumatized individuals (approximately one third) do not show hyperreactivity to threat cues.

“Yet, a subset of traumatized individuals (approximately one third) do not show such hyperreactivity to threat cues.”

With regards to acute post-traumatic dissociation, findings were similarly inconsistent, although there was some evidence of an attenuated response based on heart rate, heart rate variability and skin conductance.

“With regards to acute post-traumatic dissociation, findings were similarly inconsistent, although there was some evidence of an attenuated response (based on heart rate, heart rate variability and skin conductance) (Chou et al., 2018; D'Andrea et al., 2013; Krause-Utz et al., 2018; Sack et al., 2012).”

Several studies investigating acute post-traumatic dissociation depicted a tendency towards a hypoaroused autonomic reactivity.

“Contrary to this, several studies investigating acute post-traumatic dissociation depicted a tendency towards a hypoaroused autonomic reactivity (Chou et al., 2018; D'Andrea et al., 2013; Krause-Utz et al., 2018; Sack et al., 2012)”