Behaviorally inhibited temperament is associated with severity of post-traumatic stress disorder symptoms and faster eyeblink conditioning in veterans

Abstract

Prior studies have sometimes demonstrated facilitated acquisition of classically conditioned responses and/or resistance to extinction in post-traumatic stress disorder (PTSD). However, it is unclear whether these behaviors are acquired as a result of PTSD or exposure to trauma, or reflect preexisting risk factors that confer vulnerability for PTSD. Here, we examined classical eyeblink conditioning and extinction in veterans self-assessed for current PTSD symptoms, exposure to combat, and the personality trait of behavioral inhibition (BI), a risk factor for PTSD. A total of 128 veterans were recruited (mean age 51.2 years; 13.3% female); 126 completed self-assessment, with 25.4% reporting a history of exposure to combat and 30.9% reporting current, severe PTSD symptoms (PTSS). The severity of PTSS was correlated with current BI (R² = 0.497) and PTSS status could be predicted based on current BI and combat history (80.2% correct classification). A subset of the veterans (n = 87) also completed the eyeblink conditioning study. Among veterans without PTSS, childhood BI was associated with faster acquisition; veterans with PTSS showed delayed extinction, under some conditions. These data demonstrate a relationship between current BI and PTSS, and indicate that the facilitated conditioning sometimes observed in patients with PTSD may partially reflect personality traits such as childhood BI that pre-date and contribute to vulnerability for PTSD.

Keywords::

• Behavioral inhibition
• eyeblink
• classical conditioning
• learning
• post-traumatic stress disorder (PTSD)
• veterans

Acknowledgments

This work was partially supported by a VISN 3 Seed Grant with additional support from the SMBI, by VA Medical Research Funds, and by the NSF/NIH Collaborative Research in Computational Neuroscience (CRCNS) Program and by NIAAA (5R01 AA018737). The opinions and conclusions presented are those of the authors and are not the official position of the U.S. Department of Veterans Affairs.

Declaration of interest: The authors affirm that they have no relationships that could constitute potential conflict of interest.