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SfN Neuroblogging: PTSD in twins

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We hear a lot about PTSD these days, and with good reason. As more people confront trauma and come away with severely debilitating disorders, it becomes that much more important to understand the mechanism, in order to find ways to treat or prevent it. And one of the ways people are seeking to understand PTSD is by trying to find genetic risk factors for the disorder, in the hope that familial traits will be able to predict who might develop PTSD and who might not, allowing for preventative treatments before exposure, and better treatments after trauma.

And if you’re going to study familial components in humans, one of the best ways to do that is to study twins.

VanElzakker, et al. “Preliminary findings of neural responses to fearful facial expression in PTSD from an ongoing study of combat-discordant monozygotic twins” 795.04, II2.

For this study, the authors are looking at two different groups of twins (the study is still ongoing) recruited from the Vietnam Era Twin Registry. In the first group of twins, one twin fought in the Vietnam war and got PTSD, the other twin didn’t fight. In the second group of twins, one twin fought in Vietnam and did NOT get PTSD, and the other twin did not fight.

They took these groups of twins and put them in fMRI, where they exposed them to sets of fearful or non-fearful faces. Fearful faces can provoke a response from the amygdala, an area of the brain associated with processing emotions such as fear. People with PTSD are known to have differences in amygdala responses, and this study wanted to confirm this, as well as examining their twins, to see if there was any indication in twins who had not been exposed to combat.

They first checked to see how people subjectively responded to the faces, whether they saw fearful faces as negative and happy faces as positive. There were no differences here. The differences arose only in the fMRI scans. In the fMRI, combat veterens with PTSD showed decreases in prefrontal and cingulate cortex activation patterns compared to vets without PTSD. But what is interesting is that their non-combat exposed twins ALSO showed these changes, showing reduced activation patterns to fearful faces, while non-combat exposed twins who’s brothers did NOT have PTSD looked just like their non-PTSD brothers.

This pattern was reversed in the amygdala, where vets without PTSD and their twins showed decreases in activity (increases in prefrontal cortex activity are negatively correlated with amygdala activity, these two areas regulate each other). Vets WITH PTSD and their twins showed an increase in amygdala activation. What it ends up looking like is that vets with PTSD, AND their twins, have a failure to activate structures in the prefrontal cortex in response to fearful faces, and this change results in increased response in the amygdala. And because this effect was also seen in their non-combat exposed twins, this may mean that this activation pattern is a risk factor for PTSD, NOT a result of PTSD.

Of course these results are very preliminary (they are only halfway through the study after all). But if the findings continue in this pattern, it will help scientists to understand risk factors for PTSD that may exist long before people become exposed to traumatic situations, and give them the ability to try and intervene while they still can.

Scicurious About the Author: Scicurious is a PhD in Physiology, and is currently a postdoc in biomedical research. She loves the brain. And so should you. Follow on Twitter @Scicurious.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. zstansfi 5:49 pm 11/17/2011

    Although, what we really want to know is whether prior to war experience, such patterns of activation would have been seen in twins of whom one later developed PTSD. The obvious possibility being that brain activity being measured by fMRI is altered by PTSD in both twins, even though only one twin actually has PTSD. Really the only ethically possible (if entirely implausible) way to control for this would be to have an additional group of twins (one combat/PTSD, one no combat) who were separated at the time of combat, and did not meet again before the intiation of the study.

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  2. 2. goonghaeng 12:47 pm 11/18/2011

    I agree with “zstansfi” that another group of twins should be added. The effect feel by non-combat twin with PTSD twin could also be environmental… the fact that you have to see your twin deal with the trauma?

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  3. 3. Danny Haszard 1:25 pm 11/19/2011

    PTSD treatment for Veterans found ineffective.
    Eli Lilly Zyprexa can cause diabetes.
    I took Zyprexa Olanzapine a powerful Lilly schizophrenic drug for 4 years it was prescribed to me off-label for post traumatic stress disorder was ineffective costly and gave me diabetes.

    *FIVE at FIVE*
    The Zyprexa antipsychotic drug,whose side effects can include weight gain and diabetes, was sold for “children in foster care, people who have trouble sleeping, elderly in nursing homes.

    *Five at Five* was the Zyprexa sales rep slogan, meaning *5mg dispensed at 5pm would keep patients quiet*.
    – Daniel Haszard Zyprexa victim activist
    FMI zyprexa-victims(dot)com

    Link to this

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