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 pre-existing 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. 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 severe, current PTSD symptoms (PTSS). PTSD symptom severity 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 eyeblink conditioning. 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 suggest that the facilitated conditioning sometimes observed in PTSD patients may partially reflect personality traits such as childhood BI that pre-date and contribute to vulnerability for PTSD.

Facilitated acquisition of standard but not long delay classical eyeblink conditioning in behaviorally inhibited adolescents

“…Eyeblink sessions with excessive signal noise (loss of more than 10% of trials), incomplete session data (e.g., falling asleep), or that demonstrated a lack of a UR were discarded and not used from further analysis. Inspection of eyeblink conditioning sessions resulted in rejection of data from 45 participants, similar rejection rates were seen in previous human eyeblink studies [4][5][6]18]. …”

“…One possibility is that anxious individuals are more sensitive to the cues and contingencies in their environments, resulting in faster learning and better performance on avoidance tasks. This theory is supported by the observation of individual differences in learning in both operant and classical conditioning avoidance paradigms [4][5][6]18,19]. Although operant paradigms may seem more suited to the high cognitive processes typically associated with avoidance, eyeblink classical conditioning is an established and reliable model for understanding human learning.…”

Increased generalization of learned associations is related to re-experiencing symptoms in veterans with symptoms of post-traumatic stress

“…The CES (Keane et al, 1989) consists of 7 items that assesses frequency, duration, and amount of exposure to combat. Veterans with a total CES score <8 were classified as non-combat, while those scoring ≥8 were classified as having a history of exposure to combat, as done in previous studies (Ginsberg, Ayers, Burriss, & Powell, 2008; Myers et al, 2013; Myers, VanMeenen, McAuley, et al, 2012). The 16-item AMBI and 18-item RMBI (Gladstone & Parker, 2005) assess current (adult) and retrospective (childhood) behavioural inhibition (BI), defined as a tendency to withdraw from or avoid novel social and non-social situations; AMBI scores have been shown to correlate with measures of anxiety proneness (Gladstone & Parker, 2005; Gladstone, Parker, Mitchell, Wilhelm, & Malhi, 2005) and with self-reported PTSD symptoms (Myers, VanMeenen, McAuley, et al, 2012; Myers, VanMeenen, & Servatius, 2012).…”

Posttraumatic Stress Disorder

“…A physiologically mediated negative emotional bias may also underlie findings of (a) enhanced fear conditioning in PTSD , a possible preexisting vulnerability (Myers et al, 2012); (b) impaired safety signal learning Peri, Ben-Shakhar, Orr, & Shalev, 2000); and (c) deficits in fear extinction recall, thought to be an acquired characteristic (Milad et al, 2008). Interestingly, a common variation in the gene for an autoreceptor that restrains activation of the noradrenergic system (Neumeister et al, 2005) has been shown to be associated, even in healthy controls, with a negative emotional bias (Neumeister et al, 2006).…”