Didn't Even Blink: Dissociation, Complex Trauma Exposure and Decreased Startle Reactivity

Area of Science:

• Psychology
• Neuroscience
• Trauma Studies

Background:

• The startle eyeblink reflex orients individuals to stimuli, potentially signaling threat sensitivity.
• Attenuated startle reflexes may indicate environmental disengagement, a potential marker for dissociation.
• Previous research often associates trauma with exaggerated startle responses.

Purpose of the Study:

• To investigate the relationship between early/multiple trauma, dissociation, and PTSD symptom severity on startle reflex magnitude and habituation.
• To explore whether trauma timing influences startle response patterns.
• To examine if dissociation is associated with altered startle reactivity.

Main Methods:

• Fifty-four Black college students with trauma histories completed self-report measures for trauma exposure, PTSD symptoms, and in-task dissociation.
• Participants underwent a standard acoustic startle reflex task.
• Startle data were analyzed for nonlinear decreases in reactivity, particularly interactions between trauma features and time.

Main Results:

• Individuals with early-onset trauma (before age 6) and higher in-task dissociation exhibited significantly decreased startle reactivity.
• No significant relationship was found between multiple trauma exposures or PTSD symptom severity and startle reactivity.
• Contrary to expectations, early trauma and dissociation were associated with attenuated, not exaggerated, startle responses.

Conclusions:

• Early life trauma and dissociative experiences are associated with reduced startle reactivity, suggesting a pattern of environmental disengagement.
• These findings align with the DSM-5 Dissociative subtype of PTSD.
• The results suggest that for some individuals, therapeutic goals may need to consider fostering engagement rather than solely focusing on habituation to stressors.