[Paleopsych] BH: How Stress Causes Violence, and Vice Versa

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How Stress Causes Violence, and Vice Versa

Identification of positive feedback loop could lead to better drug
treatments for aggression

    By Gabe Romain
    Betterhumans Staff
    10/4/2004 3:25 PM

    A positive feedback loop for stress and aggression has been identified
    that helps explain such behaviors as road rage and may allow new drug
    interventions for violent behavior.

    A new study on rats has found that there seems to be a positive
    feedback loop between stress hormones called [3]glucocorticoids and
    the [4]hypothalamus--a brain area associated with a variety of
    emotions including aggression.

    The findings, by researchers from the Netherlands and Hungary, shed
    new light on the biological underpinnings of aggression and could lead
    to novel drug-based treatments for pathological violence.

    "The high stress levels of glucocorticoids, rapidly produced by the
    challenge-induced activation of brain mechanisms controlling
    aggression, may in turn produce a fast facilitation of the very same
    brain mechanisms," say the researchers. "Such mutual facilitation
    could constitute a vicious circle, which would explain why aggressive
    behavior escalates so easily, and why it is so difficult to stop once
    it has started."

    Vicious circle

    Glucocorticoids are a class of [5]steroid hormones. The most abundant
    glucocorticoid found in most organisms is [6]corticosterone, which is
    involved in regulating metabolism, immune reactions and stress

    For their study, the researchers hooked up electrodes to the brains of
    rats and then stimulated the region of the hypothalamus that is
    involved in aggression. The stimulation caused the rats to release
    corticosterone, which in turn caused the rats to display behaviors
    associated with aggression, such as teeth chattering.

    The results of the study indicate a fast-acting feedback loop--the
    mechanism works in both directions--and suggests that stress and
    aggression may be mutually reinforcing.

    "It is well known that these stress hormones, in part by mobilizing
    energy reserves, prepare the physiology of the body to fight or flee
    during stress," says lead researcher Menno Kruk, at the
    [7]Leiden/Amsterdam Center for Drug Research. "Now it appears that the
    very same hormones 'talk back' to the brain in order to facilitate

    Primed for aggression

    The researchers say that their findings suggest that rapid increases
    in corticosterone caused by stressors unrelated to fighting may
    precipitate violent behavior by lowering thresholds for attack.

    Therefore, a person could be "primed" for violent behavior if they
    were previously exposed to stressful situations. A bad day at work,
    for example, could prime someone for violence towards other drivers
    while heading home.

    Further, an anticipatory increase in corticosterone in environments
    previously associated with aggression could lead to place-dependent
    violent tendencies in people who are nonviolent in other settings, say
    the researchers.

    Treatments for pathological violence and poor impulse control have
    proven ineffective, possibly because the stress response that
    accompanies stressful situations may cancel out any beneficial effects
    of therapies aimed at reducing violent behavior.

    Although more studies are needed, the researchers speculate that
    stress-regulating drugs that help to lower acute stress-precipitated
    violence could be a viable treatment option.

    The research is reported in the journal [8]Behavioral Neuroscience
    ([9]read full text).


    3. http://www.wikipedia.org/wiki/Glucocorticoid
    4. http://www.wikipedia.org/wiki/Hypothalamus
    5. http://www.wikipedia.org/wiki/Steroid_hormone
    6. http://www.wikipedia.org/wiki/Corticosterone
    7. http://www.lacdr.nl/
    8. http://www.apa.org/journals/bne.html
    9. http://www.apa.org/journals/bne/press_releases/october_2004/bne11851062.pdf

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