Neurofunctional Differences in Cognitive and Behavioral Impulsivity in Veterans with PTSD

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Adverse outcomes, such as aggressive behavior, risk-taking, and suicide, associated with Posttraumatic Stress Disorder (PTSD) are an ongoing public health concern in Veteran populations. However, PTSD-related impulsive behavior has only recently become a major clinical research interest. Theoretical models suggest a link between PTSD and impulsivity. Cognitive neuroscience research indicates that impulsivity can be represented by two subdomains: cognitive impulsivity (also called choice impulsivity) or elevated sensitivity to immediate gratification and behavioral impulsivity (also called rapid response impulsivity) or difficulties with behavioral inhibition. Where cognitive impulsivity is associated with adverse outcomes such as risky sexual behavior and substance abuse, behavioral impulsivity is associated with violent outbursts and intimate partner violence. Research suggests that cognitive and behavioral impulsivity may have separate neuropathological origins. For example, cognitive impulsivity appears to be linked to two neurofunctional abnormalities: 1) an underperforming self-control network that extends from the dorsolateral prefrontal cortex (dlPFC) to the dorsal striatum and 2) an oversensitive reward network, which extends from ventromedial prefrontal cortex (vmPFC) to ventral striatum. On the other hand, behavioral impulsivity appears to be associated with a reduced connectivity within a right-lateralized inhibitory control pathway that extends from the right frontal region (right inferior frontal cortex, right dlPFC) and passes through the right temporoparietal region. Understanding how cognitive and behavioral impulsivity are linked to PTSD may provide a path for uncovering the different ways impulsivity and its subdomains interact with PTSD-related adverse outcomes in Veterans. Well validated, fMRI amenable tasks allow for the interrogation of separate cognitive and behavioral impulsivity neurocircuit systems, which could be utilized to further understand PTSD neuropathology. For example, temporal discounting (TD) tasks, which examine intertemporal choice between larger later reinforcers and smaller sooner ones provide a simple yet quantifiable index of cognitive impulsivity. Similarly, go-no-go (GNG) tasks have been shown to be effective in assessing behavioral impulsivity by examining the frequency of commission errors (i.e. when a participant responds to no-go stimuli). However, investigations that have examined the neuroactivation and functional connectivity that underlie PTSD – related impulsivity and its subdomains in Veteran populations are sparse. Therefore, we aim to 1) use an fMRI TD task to examine the functional neuroanatomical underpinnings of cognitive impulsivity in Veterans with PTSD and 2) use an fMRI GNG task to examine the functional neuroanatomical underpinnings of behavioral impulsivity in Veterans with elevated PTSD levels. Examining PTSD-related impulsivity within the context of broader neural network dysfunction may lead to the development of novel, neurocircuit based, patient-centered treatments that are tailored toward malleable cognitive and behavioral impulsivity-related targets linked to adverse health outcomes for Veterans with PTSD.