JOURNALHeide

10.1177/0886260504268119
Solomon, OF INTERPERSON
/ THE BIOLOGY
AL OF
VIOLENCE
TRAUMA/ January 2005

The Biology of Trauma

Implications for Treatment

ELDRA P. SOLOMON
Center for Mental Health Education, Assessment, and Therapy, Tampa
KATHLEEN M. HEIDE
University of South Florida

During the past 20 years, the development of brain imaging techniques and new bio-
chemical approaches has led to increased understanding of the biological effects of
psychological trauma. New hypotheses have been generated about brain develop-
ment and the roots of antisocial behavior. We now understand that psychological
trauma disrupts homeostasis and can cause both short- and long-term effects on
many organs and systems of the body. Our expanding knowledge of the effects of
trauma on the body has inspired new approaches to treating trauma survivors. Bio-
logically informed therapy addresses the physiological effects of trauma, as well as
cognitive distortions and maladaptive behaviors. The authors suggest that the most
effective therapeutic innovation during the past 20 years for treating trauma survi-
vors has been Eye Movement Desensitization and Reprocessing (EMDR), a thera-
peutic approach that focuses on resolving trauma using a combination of top-down
(cognitive) and bottom-up (affect/body) processing.

Keywords: psychological trauma; biology of trauma; neurobiology; Post-

Traumatic Stress Disorder; PTSD; effects of psychological trauma on
brain development; Eye Movement Desensitization and Reprocessing;
EMDR; child abuse; child neglect

Both public and professional interest in the effects of trauma have greatly
increased as we have experienced the worldwide proliferation of violence,
including the terrorist attacks on September 11, 2001, in the United States,
the train bombings in Spain in 2004, and escalation of armed conflict in many
parts of the world including Afghanistan, Iraq, and other parts of the Middle
East. During the past 20 years, with the help of more sophisticated research
tools, we have begun to understand the biological basis of both trauma and
violence. With the advent of brain imaging techniques and new biochemical
approaches, we are beginning to comprehend the complexities of the rela-

JOURNAL OF INTERPERSONAL VIOLENCE, Vol. 20 No. 1, January 2005 51-60

DOI: 10.1177/0886260504268119
© 2005 Sage Publications

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52 JOURNAL OF INTERPERSONAL VIOLENCE / January 2005

tionships among experience, neurophysiology, endocrinology, and behavior.

As a result of this expanding knowledge, we have developed an appreciation
for the widespread, long-term effects of psychological trauma on the body
as well as the mind, and we are exploring new ways of effectively treating
trauma survivors.
During the next 10 years, as we continue to study the development and
neurophysiology of the brain, we will dramatically increase our understand-
ing of how the brain is affected by trauma. We will learn more about the
effects of psychological trauma on neurotransmitter receptors, synaptic con-
nections, and hormone interactions and how those effects are translated into
behavior. Based on our expanding understanding of the biology of trauma,
we will continue to develop more effective treatment strategies.
Recent findings concerning the biology of trauma challenge clinicians
to embrace treatment methods that address biological effects. Cognitive-
behavioral therapy offers many strategies that are helpful in treating trauma
survivors. However, trauma is far more than a cognitive issue. Traumatic
experience is largely affective and somatic, and effective treatment must also
address the body. The most promising methodological innovation in the past
20 years for the treatment of trauma has been Eye Movement Desensitization
and Reprocessing (EMDR).

BIOLOGICAL EFFECTS OF
TRAUMATIC STRESS

Traumatic experiences cause traumatic stress, which disrupts homeosta-

sis. During the past few years, we have dramatically increased our under-
standing of the effects of traumatic stress on the brain, sympathetic nervous
system, and endocrine system. Through a physiological domino effect, these
changes affect many other body systems, including the cardiovascular sys-
tem, respiratory system, and muscular system.

Some Effects of Traumatic Stress

on the Endocrine System
The endocrine system works closely with the nervous system to regulate
the body’s physiology. Traumatic experience causes both immediate and
long-term endocrine changes that affect metabolism and neurophysiology.
The sympathetic nervous system is immediately affected by any perception
of danger and signals the adrenal medulla to greatly increase its output of epi-

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 Solomon, Heide / THE BIOLOGY OF TRAUMA 53

nephrine and norepinephrine. These hormones rapidly affect many body sys-
tems leading to a fight-or-flight response. If neither response is possible, the
person freezes.
During stress, the hypothalamic-pituitary-adrenal system is also acti-
vated, leading to increased levels of cortisol, a glucocorticoid released by the
adrenal cortex that modulates the physiologic response to stress and helps
activate effective coping strategies. Cortisol concentration has been the focus
of several recent studies because abnormally high levels of cortisol, associ-
ated with stress, can damage neurons in the hippocampus.
Abnormal concentrations of adrenal hormones depress the immune sys-
tem and contribute to the physiological hyperarousal (e.g., exaggerated star-
tle response, hypervigilance) characteristic of PTSD. Chronic physiological
hyperarousal makes it very difficult to regulate autonomic responses to inter-
nal or external signals and decreases the ability to respond appropriately to
emotional signals (van der Kolk, 1996). In chronic stress and in Post-Trau-
matic Stress Disorder (PTSD), cortisol concentrations are lower than would
be expected, and exposure to new stressors elicits lower levels of cortisol
secretion.

Some Effects of Traumatic Stress on the Brain

Brain studies using functional magnetic resonance imaging (FMRI), posi-
tron emission tomography (PET), magnetic resonance spectroscopy (MRS),
and electroencephalogram (EEG) allow researchers to study the brain in
action (Villarreal & King, 2001). Using photon emission tomography
(SPECT), neurobiologists can now analyze the density of brain receptors.
Studies of the brains of human and animal subjects who have been victims of
traumatic stress reveal differences in their brains when compared with con-
trol subjects who have not experienced trauma. These changes in brain struc-
ture and physiology are thought to affect memory, learning, ability to regu-
late affect, social development, and even moral development.
To understand the problems presented by traumatic memories, we will
first review how nontraumatic memories are processed. Memories of ordi-
nary experiences are temporarily stored in the limbic system as episodic
memories, memories of personal experience and events. Episodic memories
are autobiographical; they include a sense of time and self. Cognitive aspects
are stored in the hippocampus and the associated emotion is stored in the
amygdala. As the brain processes these memories over time, aspects of them
are abstracted and transferred to the neocortex, particularly the association
areas of the frontal lobes, for long-term storage. These memories are seman-

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54 JOURNAL OF INTERPERSONAL VIOLENCE / January 2005

tic, or factual, memories. (Episodic and semantic memories are two types of
explicit memory.)
The memories of moderately disturbing experiences apparently remain in
the right limbic system for a longer period of time than the memories of neu-
tral events. We process disturbing memories by thinking, talking, and some-
times dreaming about the experience. As the brain slowly processes the
memory, it is abstracted and transferred into the left neocortex where it is
filed away along with other memories and becomes part of the narrative of
one’s life. The stored information can be retrieved when needed to under-
stand future events.
Traumatic events overwhelm the brain’s capacity to process information.
The episodic memory of the experience may be dysfunctionally stored in the
right limbic system indefinitely and may generate vivid images of the trau-
matic experience, terrifying thoughts, feelings, body sensations, sounds, and
smells. Such unprocessed traumatic memories can cause cognitive and emo-
tional looping, anxiety, PTSD, maladaptive coping strategies, depression,
and many other psychological symptoms of distress. Because the episodic
memory is not processed, a relevant semantic memory is not stored and
the individual has difficulty using knowledge from the experience to guide
future action.
Because traumatic experiences are terrifying, the survivor avoids think-
ing and talking about what happened. This avoidance prevents processing.
Trauma alters physiology and gives rise to images, feelings, sensations, and
beliefs that may persist throughout life. Only after the traumatic memory is
fully processed and integrated can homeostasis be restored.
Traumatic memories can be triggered by stimuli that are in some way
associated with the traumatic event. Terrifying memories, including the
affect associated with them, may be reexperienced with their original inten-
sity. Survivors feel the terror and may lose their sense of time and place. One
client stated, “Part of me knows it’s not really happening now, but it feels so
real that I get mixed up.”
Brain scan technology enables us to study the brain in action. Using PET
scans, researchers have demonstrated some of the neurophysiological effects
that take place when traumatic memory is triggered. In one study, partici-
pants were asked to write detailed narratives of their traumatic experience
(Rauch et al., 1996). Then, each participant was asked to read the narrative
during brain scanning. The results were dramatic. Activity increased in the
right brain, primarily in the limbic system and in the visual cortex (the site
of vivid images of the event). Activity decreased in the anterior cingulate

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 Solomon, Heide / THE BIOLOGY OF TRAUMA 55

cortex (ACC), which normally modulates the limbic system. Activity also
decreased in Broca’s area, an area of the brain important in semantic process-
ing and articulation of language. This decrease in activity may be the
neurophysiological basis for the “speechless terror” that many individuals
experience both during a traumatic event and when processing trauma in
therapy.
In the United States, child abuse and neglect are the most common causes
of Type III trauma, extreme trauma characterized by multiple traumatic expe-
riences that typically begin at an early age (Solomon & Heide, 1999). An
infant’s relationship with its primary caregiver has a direct effect on the hard
wiring of neural circuits in the developing brain. Many of the neural circuits
affected by early experience connect areas of the brain critical for emotional,
physiological, psychological, and social development. Some of these cir-
cuits are necessary for adaptive coping in emotional and stressful situations
(Schore, 2003).
The orbitofrontal cortex helps regulate emotional states and responses. By
way of its connections with the hypothalamus and limbic system, it regulates
autonomic responses to social stimuli and mediates emotionally “attuned
communication.” This part of the cortex helps us understand other people’s
emotional experience, enabling us to respond empathically, a capacity neces-
sary for moral judgment. Normal development of the right brain and later
emotional and social development depend on healthy attachment between
infant and caregiver (Schore, 1994, 1996, 2003).
Children who are severely neglected experience chronic traumatic stress
that compromises right brain development, resulting in neuron damage and
atrophy. Impairment of the orbitofrontal cortex and the circuits connecting it
with subcortical areas can diminish the child’s sense of self, leading to dis-
connection from other people. Severely neglected children do not deal well
with stress and do not develop the ability to regulate the intensity and dura-
tion of their affect (Schore, 2002; van der Kolk & Fisler, 1994). Because
these children have difficulty understanding emotion expressed by other peo-
ple, they may not develop empathy.
Many studies conclude that impaired development of the orbitofrontal
cortex and its neural connections with the limbic system decreases capacity
to regulate affect. For example, the orbitofrontal cortex normally inhibits
areas in the hypothalamus that are associated with aggression and thus is cen-
tral in the regulation of aggressive impulses. Abnormal development of the
neural circuits linking the orbitofrontal cortex and ACC with the amygdala
interferes with normal inhibition of rage responses. Without the normal cor-

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56 JOURNAL OF INTERPERSONAL VIOLENCE / January 2005

tical modulating effect, the amygdala’s responses are exaggerated. When

aggressive impulses are not inhibited, an individual may act out violently.
This lack of inhibition is part of the pattern of sociopathy (Best, Williams, &
Coccaro, 2002; Schore, 2003). Studies suggest that trauma caused by neglect
and abuse can lead to antisocial behavior (Heide, 1992, 1999).
Many long-term changes in the brain have been associated with Type III
trauma, including abnormal concentrations of certain neurotransmitters,
changes in EEG patterns, and a decrease in integration between right and left
hemispheres. Measurable size decreases have been found in the cerebral vol-
ume, the corpus callosum, amygdala, and hippocampus. Whether or not
these changes are reversible with treatment is an important question for
future study.

BIOLOGICALLY INFORMED TREATMENT

I’m 44 years old and I’ve been to at least eight therapists since I was abducted
and raped at age 15. I’ve talked about it over and over. . . . I’m tired of talking
about it . . . and it’s still here . . . still affecting my life. I just want to move past
it. . . . I want to feel better.

Many trauma survivors share Debbie’s experience in therapy—and her frus-

tration. Talking alone doesn’t make “it” go away. Consequently, as our
understanding of the biological nature of trauma has increased over the past
several years, many therapists have modified their treatment approach.
Most traditional therapies, including cognitive-behavioral therapy (CBT),
depend on top-down processing in which the client is taught to use cognitive
strategies to manage or inhibit problematic feelings, thoughts, and behaviors
(the neocortex rules the body). For example, CBT helps clients understand
how traumatic experience has affected them and helps them change errone-
ous beliefs or maladaptive ways of thinking or behaving. This approach helps
clients gain insight into their way of being in the world. Clients may learn to
identify stimuli that trigger them and understand their responses. They may
learn to manage disturbing emotions and body sensations. Top-down ap-
proaches, however, do not process the episodic memories or resolve physio-
logical hyperarousal. Consequently, clients are still triggered by stimuli that
their limbic systems perceive as dangerous and they may still respond in mal-
adaptive ways. Even with years of therapy, immediate responses to triggering
stimuli tend to be physiological rather than logical.

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Biologically informed therapy focuses on processing traumatic experi-

ence. Episodic memories are processed and information transferred from the
limbic system to the neocortex and filed away along with other narrative
memories. Biologically informed therapy includes bottom-up processing,
which focuses on what is going on in the body. This approach helps clients
connect with their bodies and with their feelings. It facilitates their learning
to tolerate intense feelings and to release emotion appropriately. Survivors
learn to calm their physiology.

Eye Movement Desensitization and Reprocessing

Although several treatment approaches have been developed that focus on

the biological aspects of trauma recovery, we focus here on Eye Movement
Desensitization and Reprocessing (EMDR) because its effectiveness has
been demonstrated by several empirical studies (Servan-Schreiber, 2000;
Shapiro, 1999). EMDR is an effective combination of body-focused
(bottom-up processing) and cognitive-behavioral (top-down processing)
treatment. Developed by psychologist Francine Shapiro during the 1990s,
EMDR helps the trauma survivor access and process traumatic memories so
that they can be brought to an adaptive resolution (Shapiro, 2001).
During EMDR, which uses structured protocols, the client is asked to
identify a disturbing image that represents the worst part of the traumatic
event and to identify negative beliefs about self stemming from the experi-
ence. The therapist asks the client to formulate a positive cognition that could
replace the negative belief and then to notice the feelings and body sensations
associated with the disturbing memory/image. The client is instructed to hold
the disturbing event/image in mind along with the associated negative belief,
feelings, and sensations in the body while focusing on an external stimulus.
The client is asked to track the therapist’s moving fingers/hand back and
forth in front of his or her visual field for about 20 to 50 seconds. After each
set of bilateral stimulation, the client is asked what comes up or what changes
his or her experiences. Rating scales are used throughout each session to doc-
ument changes in the intensity of feelings and body sensations. Eye move-
ment can be replaced by alternating right-left tactile stimuli (e.g., alternately
tapping right and left hands) or by alternating right-left tones. As the client
focuses on the traumatic experience and associated negative beliefs, feelings,
and sensations, the episodic memory is processed and consolidated as a nar-
rative memory bringing the client to an adaptive resolution.

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58 JOURNAL OF INTERPERSONAL VIOLENCE / January 2005

Cognitive components of the EMDR protocol include asking the client

to develop positive cognitions/antidotes for negative self-beliefs. (This is a
form of cognitive restructuring in which the client replaces negative, psycho-
logically unhealthy beliefs with more adaptive beliefs.) In the EMDR strat-
egy referred to as the “cognitive interweave,” the therapist cognitively assists
a client who is looping or who lacks necessary information. The client also
learns containment strategies for managing intense feelings, for example,
learning to shift out of anxiety or intense affect by going to a safe place
(beach, mountain, lake) in his or her mind.
The neurophysiological basis of EMDR is not known with certainty, but
several hypotheses have been suggested. In EMDR, visual, tactile, or audi-
tory stimuli alternately stimulate right and left sides of the brain, forcing a
shift of attention across the midline. Stickgold (2002) hypothesized that the
repetitive redirecting of attention in EMDR induces a REM sleep-like state, a
neurobiological state that facilitates the activation of episodic memories.
These memories are processed and integrated into neural networks in the
neocortex as semantic (narrative) memory. The work of Christman and
Garvey (Christman, Garvey, Propper, & Phaneuf, 2003) supports Stickgold’s
hypothesis. These researchers found that alternating eye movements en-
hanced episodic memory retrieval tasks but not narrative memory retrieval
tasks.
In one very interesting study, SPECT scans were administered before and
after EMDR treatment for six PTSD participants who each received three
EMDR sessions (Levin, Lazrove, & van der Kolk, 1999). The investigators
reported an increase in bilateral activity in the ACC, a part of the brain that
modulates the limbic system and helps us distinguish real from perceived
(but not real) threat. The increase in ACC activity suggests a decrease in
hypervigilance. These researchers also found an increase in prefrontal lobe
metabolism, suggesting greater ability to make sense of incoming sensory
stimulation.
Advances in science in the 21st century are confirming what Freud sug-
gested nearly 100 years ago. Behavior is more than psychologically deter-
mined. Human development, including behavior, is biologically guided. In
contrast to Freud’s thinking, however, the latest findings with respect to
human trauma suggest that individuals can gain mastery over their destiny by
participating in therapeutic strategies that consider both the biological and
psychological roots of human development. EMDR is an effective treatment
modality that considers both. A 38-year-old trauma survivor described her
experience with EMDR as follows:

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 Solomon, Heide / THE BIOLOGY OF TRAUMA 59

I feel myself shifting. For the first time, I’m paying as much attention to dealing
with my life as it is now, as to dealing with my life as it was back then.

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Eldra P. Solomon, Ph.D., is both a licensed psychologist and a biologist. She has written
several leading college biology and human anatomy and physiology textbooks. The 7th
edition of Biology, her textbook for biology majors, was recently published. In her clini-
cal practice, she specializes in treating clients who have survived traumatic experiences.
She serves as a clinical consultant for psychologists and other mental health profession-
als and does training and workshops focused on psychological trauma and its treatment.
She taught college biology for more than 20 years and has taught courses in criminology
at the University of South Florida, Tampa, where she has been a member of the graduate
faculty.

Kathleen M. Heide, Ph.D., is a professor of criminology at the University of South

Florida, Tampa. She received her B.A. in psychology from Vassar College and her M.A.
and Ph.D. in criminal justice from the University at Albany, State University of New York.
She is a licensed psychotherapist and an internationally recognized consultant on homi-
cide and family violence. Her extensive publication record includes two widely ac-
claimed books on juvenile homicide. Her latest book, published in 2004, entitled Animal
Cruelty: Pathway to Violence Against People, is a scientific examination of the link
between animal cruelty and human violence.

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