Increased response variability as a marker of executive dysfunction in veterans with post-traumatic stress disorder

Abstract

The stability of cognitive control processes over time can be indexed by trial-to-trial variability in reaction time (RT). Greater RT variability has been interpreted as an indicator of executive dysfunction, inhibitory inefficiency, and excessive mental noise. Previous studies have demonstrated that combat veterans with post-traumatic stress disorder (PTSD) show substantial impairments in inhibitory control, but no studies have examined response variability in this population. In the current experiment, RT variability in the Go/NoGo response inhibition task was assessed for 45 veterans with PTSD and 34 control veterans using the intra-individual coefficient of variation and ex-Gaussian analysis of RT distributions. Despite having mean RTs that were indistinguishable from controls, the PTSD patients had significantly greater RT variability, which was not solely due to attentional lapses. More variable RTs were in turn associated with a greater number of false alarm errors, suggesting that less consistent performers were less successful at inhibiting inappropriate responses. RT variability was also highly correlated with self-reported symptoms of PTSD, depression, and attentional impulsiveness. Furthermore, response variability predicted diagnosis even when controlling for PTSD symptom severity. In turn, PTSD severity was correlated with self-rated attentional impulsiveness. Deficits in the sustained attention and top-down cognitive control processes that cause greater response variability might contribute to the maintenance of PTSD symptomology. Thus, the distractibility issues that cause more variable reaction times might also result in greater distress related to the trauma.

Executive Dysfunctions: The Role in Attention Deficit Hyperactivity and Post-traumatic Stress Neuropsychiatric Disorders

“…In fact, the increased variability in RTs in ADHD is a highly replicable finding (Hervey et al, 2006; Swick et al, 2013; Tarantino et al, 2013). Among the various explanations for this increased RT variability are: deficits in sustained attention, problems processing time information, and difficulties in regulating behavior (Johnson et al, 2007; Tamm et al, 2012), resulting in a general marker of executive dysfunction (Ode et al, 2011).…”

Dissociation between working memory performance and proactive interference control in post-traumatic stress disorder

“…The participants were combat Veterans with PTSD and age-matched control Veterans. Our previous results indicated this patient population is impaired on some cognitive control tasks, with more errors of commission and more variable RTs in a Go/NoGo task (Swick et al, 2012, 2013). However, other cognitive control functions are preserved, including error monitoring and interference resolution in the flanker task (Swick et al, 2015).…”

The influence of short-term firefighting activity on information processing performance

“…Ideally, firefighters would have higher levels of energy/ lower levels of tiredness at the beginning of their duty shift which may translate into more effective management of multiple pieces of information, consistent cognitive performance, and potentially fewer errors (e.g. Swick et al 2013). This could be achieved through maintaining proper sleep, nutrition, physical activity, and fitness (Thayer 2001).…”