SNI Study News

Risk-Taking Behaviors and Impulsivity Among Veterans With and Without

Posttraumatic Stress Disorder

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.

and Mild TBI

Military personnel commonly experience post-traumatic stress disorder () and mild traumatic brain injury (mTBI), both of which are associated with premature mortality. The present study examined two factors that may play a role in premature mortality-impulsivity and risk-taking behaviors-in a sample of 234 veterans screening positive for , mTBI, + mTBI, and controls. Analyses of variance demonstrated that veterans with , regardless of mTBI status, reported engaging in more frequent risky behaviors and reported a greater tendency to engage in impulsive behaviors when in a negative affective state. They also reported more premilitary delinquent behaviors and more suicide-related behaviors than controls. The present study highlights associations between impulsivity, risk-taking behaviors, and , and suggests continuity across the lifespan in terms of a predisposition to engage in impulsive and/or risky behaviors. Thorough evaluation of impulsivity and potentially risky behaviors is important in clinical settings to guide interventions and reduce the mortality and public health impact of high-risk behaviors in veterans.

The trail of trauma

When a disaster strikes, groups of people spontaneously form and start talking all at once.And your brain does the same thing in response to personal trauma. Groups of neurons in the cerebral cortex start firing at the same time, "talking" to each other, and get locked into a correlated pattern of activity. Previous work by University of Minnesota researchers identified a particular pattern so strongly associated with post-traumatic stress disorder () that they can clearly tell who has . Now, a new study shows that in people with , these patterns persist, just as do the intrusive, incapacitating memories or re-experiencing of the events, emotional numbing, and hyperarousal that define the disorder.

But, they found, in people who have not developed despite exposure to trauma, the patterns lack staying power. In them, "these patterns loosen and dissipate over weeks, months, or days," says lead researcher Lisa James, an assistant professor in the U's Department of Psychiatry and a researcher in the at the Minneapolis , where the study took place. "This wipes the slate clean."

"Our work means that in resilient people the brain can actively adapt to traumatic experiences in a way that those with cannot. The better we understand the brain mechanisms associated with , the sooner we can apply that knowledge to evaluating treatment efficacy."

Co-author Apostolos Georgopoulos likens the situation in a trauma-exposed brain to an infection.

How

Magnetoencephalography

Magnetoencephalography (MEG)

A noninvasive technique that detects magnetic fields above the surface of the head produced by postsynaptic potentials in the brain.

works

The advantage of is its ability to detect brain activity on a scale of milliseconds. The researchers placed an apparatus resembling a helmet over the heads of the subjects, who were asked to fixate on a stationary dot with their eyes for 60 seconds. The helmet contained 248 sensors, each of which detected the magnetic fields generated in a population comprising tens of thousands of cortical cells. Together, the sensors scanned the magnetic activity over the whole cortex.

'It's like having a disease, where you make antibodies," says Georgopoulos, a Regents Professor of neuroscience and director of the . "If you can't make antibodies, you don't adapt to the virus. Similarly, if you don't de-correlate your brain networks, you're still sick."

Short-term tracking of the -linked patterns in people exposed to trauma could potentially identify those who are resilient vs. those who need treatment. Pattern tracking could also be used to monitor progress during treatments or to validate a simpler test for resilience, such as genetic or personality traits, the researchers say.

The work is published online in the journal JAMA Psychiatry.

How to eavesdrop on brain chatter

The researchers studied 86 veterans with and 113 veterans who were resilient to trauma. A questionnaire revealed the extent of their exposure to trauma; those with trauma exposure but no were, by definition, resilient controls.

The team used a noninvasive technique called (; see sidebar)) to study the magnetic fields generated in neurons of the right temporal lobe cortex as they received messages during neuronal "talk." Neurons receiving messages experience movements of ions across their outer membranes; these movements generate the magnetic fields.

The measured the strength of correlated patterns of activity in cell populations-i.e., simultaneous generation of magnetic fields-characteristic of . They discovered:

Among controls, weaker -related patterns tended to occur in those with highertrauma scores. In other words, "In controls, big trauma leads to a big adaptation," says Georgopoulos.

Also in controls, the right temporal cortex had a crucial node in which brain activity was decorrelated, a signal of adaptation. This area of the brain is a focus of future study.

Resilience isn't an all-or-nothing trait, but a continuum.

The trauma landscape

Most people are resilient to some events, so the question becomes: Why isn't everybody?

"About 60 to 90 percent of people will experience a potentially traumatic event in their lifetime, like a car accident or the sudden death of a loved one, but they are resilient. They don't develop symptoms of a psychiatric disorder," says James.

"Only seven percent of people in the general population and about 20 percent of veterans develop . Most come back [from service] without -what enables them to do that?"

To answer that question, the researchers are turning their attention to a search for genetic markers of resilience. If certain genes or, perhaps, personality traits, are found to be associated with resilience, that could allow researchers to predict one's degree of resilience before trauma hits.

" sufferers have options that include medications, talk therapy, and interventions to treat nightmares," James says. "We're interested in what happens in the brain as individuals with respond to treatment."

Risk and Protective Factors Associated With Symptoms of Post-Traumatic Stress, Depression, and Alcohol Misuse in

Operation Enduring Freedom - Afghanistan

Operation Enduring Freedom - Afghanistan (OEF)

The U.S. government used the term "Operation Enduring Freedom - Afghanistan" (OEF) to officially describe the War in Afghanistan, from the period between October 2001 and December 2014. ... Continued operations in Afghanistan by the United States' military forces, both non-combat and combat, now occur under the name "Operation Freedom's Sentinel".

/

Operation Iraqi Freedom

Operation Iraqi Freedom (OIF)

The period of the Iraq war lasting from 2003 to 2010 was referred to as Operation Iraqi Freedom (OIF) by the United States military. The conflict is also known as the War in Iraq, the Occupation of Iraq, the Second Gulf War, Gulf War II, and Gulf War 2.

Veterans

Military personnel returning from the conflicts in Iraq and Afghanistan commonly experience mental health problems and efforts are underway to determine risk and protective factors associated with postdeployment mental health concerns. This study examined the contribution of trait neuroticism, predeployment life events, combat experience, perceptions of threat, and postdeployment social support on mental health symptoms at 6 months, 12 months, and 24 months postdeployment. Two hundred seventy-one veterans completed self-report measures. Hierarchical regression analyses demonstrated that neuroticism predicted post-traumatic stress and depressive symptoms at all 3 time points; perceived threat predicted post-traumatic stress symptoms at Time 1 and Time 2 and depressive symptoms at Time 2. Social support was a strong negative predictor of post-traumatic stress and depressive symptoms. Alcohol misuse was not significantly predicted by any of the variables. The present study highlights the role of perceived threat and trait neuroticism on postdeployment mental health symptoms and indicates social support is a robust protective factor. Efforts aimed at increasing sustained postdeployment social support may help defend against significant mental health problems among veterans.

Neural Network Modulation by Trauma as a Marker of Resilience Differences Between Veterans With

Posttraumatic Stress Disorder

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.

and Resilient Controls

Importance and resilience reflect 2 distinct outcomes after exposure to potentially traumatic events. The neural mechanisms underlying these different outcomes are not well understood.

Objective To examine the effect of trauma on for veterans with and resilient controls using magnetoencephalography.

Design Participants underwent diagnostic interviews, a measure of exposure to potentially traumatic events, and magnetoencephalography.

Setting US Department of Veterans Affairs medical center.

Participants Eighty-six veterans with and 113 resilient control veterans recruited from a large Midwestern medical center.

Main Outcome Measures Multiple regression analyses were performed to examine the effect of lifetime trauma on global and local . In analyses examining the local , the partial regression coefficient indicates the strength and direction of the effect of trauma on the synchronous interactions between the 2 neural signals recorded by a pair of sensors. The partial regression coefficient, or slope, is the primary outcome measure for these analyses.

Results Global were significantly modulated downward with increasing lifetime trauma scores in resilient control veterans (P = .003) but not in veterans with (P = .91). This effect, which was primarily characterized by negative slopes (ie, decorrelations) in small neural networks, was strongest in the right superior temporal gyrus. Significant negative slopes were more common, stronger, and observed between sensors at shorter distances than positive slopes in both hemispheres (P < .001 for all) for controls but not for veterans with PTSD.

Conclusions Neural modulation involving decorrelation of neural networks in the right superior temporal gyrus and, to a lesser extent, other areas distinguishes resilient veterans from those with and is postulated to have an important role in healthy response to trauma.

Canonical correlation analysis of

Synchronous Neural Interactions

Synchronous Neural Interactions (SNI)

Zero-lag partial correlations in pairs of MEG time series and denote the strength and polarity (positive or negative) of neuronal interactions. Anomalies in SNIs as assessed by MEG differentiate psychiatric disorders from healthy brain functioning and can discriminate among various brain diseases. From this research, a highly distinctive, unique PTSD SNI signature characterized by miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas has emerged. These findings, in addition to the growing research applying MEG to other psychiatric disorders, highlight the utility of MEG in identifying biomarkers of disease and underscore the potential for broader clinical applications of MEG.

and cognitive deficits in Alzheimer's dementia

In previous work (Georgopoulos et al 2007 J. Neural Eng. 4 349-55) we reported on the use of magnetoencephalographic () as a functional biomarker in Alzheimer's dementia (AD) diagnosis. Here we report on the application of canonical correlation analysis to investigate the relations between and cognitive neuropsychological (NP) domains in AD patients. First, we performed individual correlations between each and each NP, which provided an initial link between and specific cognitive tests. Next, we performed factor analysis on each set, followed by a canonical correlation analysis between the derived and NP factors. This last analysis optimally associated the entire signal with cognitive function. The results revealed that as a whole were mostly associated with memory and language, and, slightly less, executive function, processing speed and visuospatial abilities, thus differentiating functions subserved by the frontoparietal and the temporal cortices. These findings provide a direct interpretation of the information carried by the and set the basis for identifying specific neural disease phenotypes according to cognitive deficits.

Post-traumatic stress disorder: a right temporal lobe syndrome?

In a recent paper (Georgopoulos et al 2010 J. Neural Eng. 7 016011) we reported on the power of the -based test to differentiate post-traumatic stress disorder () subjects from healthy control subjects and to classify them with a high degree of accuracy. Here we show that the main differences in cortical communication circuitry between these two groups lie in the miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas. This lateralized temporal-posterior pattern of miscommunication was very similar but was attenuated in patients with in remission. These findings are consistent with observations (Penfield 1958 Proc. Natl Acad. Sci. USA 44 51-66, Penfield and Perot 1963 Brain 86 595-696, Gloor 1990 Brain 113 1673-94, Banceaud et al 1994 Brain 117 71-90, Fried 1997 J. Neuropsychiatry Clin. Neurosci. 9 420-8) that electrical stimulation of the temporal cortex in awake human subjects, mostly in the right hemisphere, can elicit the re-enactment and re-living of past experiences. Based on these facts, we attribute our findings to the re-experiencing component of and hypothesize that it reflects an involuntarily persistent activation of interacting neural networks involved in experiential consolidation.

The

Synchronous Neural Interactions

Synchronous Neural Interactions (SNI)

Zero-lag partial correlations in pairs of MEG time series and denote the strength and polarity (positive or negative) of neuronal interactions. Anomalies in SNIs as assessed by MEG differentiate psychiatric disorders from healthy brain functioning and can discriminate among various brain diseases. From this research, a highly distinctive, unique PTSD SNI signature characterized by miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas has emerged. These findings, in addition to the growing research applying MEG to other psychiatric disorders, highlight the utility of MEG in identifying biomarkers of disease and underscore the potential for broader clinical applications of MEG.

test as a functional neuromarker for post-traumatic stress disorder (

Posttraumatic Stress Disorder

Posttraumatic Stress Disorder (PTSD)

A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.

): a robust classification method based on the bootstrap

Traumatic experiences can produce post-traumatic stress disorder () which is a debilitating condition and for which no biomarker currently exists (Institute of Medicine (US) 2006 : Diagnosis and Assessment (Washington, DC: National Academies)). Here we show that the test which assesses the functional interactions among neural populations derived from magnetoencephalographic () recordings (Georgopoulos A P et al 2007 J. Neural Eng. 4 349-55) can successfully differentiate patients from healthy control subjects. Externally cross-validated, bootstrap-based analyses yielded >90% overall accuracy of classification. In addition, all but one of 18 patients who were not receiving medications for their disease were correctly classified. Altogether, these findings document robust differences in brain function between the and control groups that can be used for differential diagnosis and which possess the potential for assessing and monitoring disease progression and effects of therapy.

P2-027: Association of cognitive deficits with

Synchronous Neural Interactions

Synchronous Neural Interactions (SNI)

Zero-lag partial correlations in pairs of MEG time series and denote the strength and polarity (positive or negative) of neuronal interactions. Anomalies in SNIs as assessed by MEG differentiate psychiatric disorders from healthy brain functioning and can discriminate among various brain diseases. From this research, a highly distinctive, unique PTSD SNI signature characterized by miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas has emerged. These findings, in addition to the growing research applying MEG to other psychiatric disorders, highlight the utility of MEG in identifying biomarkers of disease and underscore the potential for broader clinical applications of MEG.

as revealed by magnetoencephalography: A canonical correlation analysis

In a recent study we showed that assessed by in a simple fixation test can be used as a functional biomarker for brain disorders (Georgopoulos et al., J. Neural Engineer. 4:349-355, 2007). The variables consist of partial zero-lag cross-correlations estimated between pairs of 248 axial gradiometer sensors after prewhitening of the time series. In this study we evaluated the relations between cognitive deficits and .

Synchronous Neural Interactions

Synchronous Neural Interactions (SNI)

Zero-lag partial correlations in pairs of MEG time series and denote the strength and polarity (positive or negative) of neuronal interactions. Anomalies in SNIs as assessed by MEG differentiate psychiatric disorders from healthy brain functioning and can discriminate among various brain diseases. From this research, a highly distinctive, unique PTSD SNI signature characterized by miscommunication of temporal and parietal and/or parieto-occipital right hemispheric areas with other brain areas has emerged. These findings, in addition to the growing research applying MEG to other psychiatric disorders, highlight the utility of MEG in identifying biomarkers of disease and underscore the potential for broader clinical applications of MEG.

assessed by magnetoencephalography: a functional biomarker for brain disorders

We report on a test to assess the dynamic brain function at high temporal resolution using . The essence of the test is the measurement of the dynamic , an essential aspect of the brain function. signals were recorded from 248 axial gradiometers while 142 human subjects fixated a spot of light for 45-60 s. After fitting an autoregressive integrative moving average (ARIMA) model and taking the stationary residuals, all pairwise, zero-lag, partial cross-correlations (PCCij0) and their z-transforms (zij0) between i and j sensors were calculated, providing estimates of the strength and sign (positive, negative) of direct synchronous coupling at 1 ms temporal resolution. We found that subsets of zij0 successfully classified individual subjects to their respective groups (multiple sclerosis, Alzheimer's disease, schizophrenia, Sj"ogren's syndrome, chronic alcoholism, facial pain, healthy controls) and gave excellent external cross-validation results.