An article in the March 2002 issue of Scientific American,
entitled Scars That Won't Heal: the Neurobiology of Child Abuse,
described presumably permanent damage to the developing brain as
a result of severe neglect or repeated physical or sexual abuse.
The changes were observed in studies of EEG's, which measure
electrical activity in the brain, and MRI scans, which provide
detailed pictures of the structure of the brain.
Specific findings were of several types. EEG studies showed
a significant increase in the incidence of brain wave abnormalities
in adult victims of incest or physical abuse compared with adults
who had no history of abuse. Another study was cited in which
adult victims of incest were found to have an increased incidence
of seizure activity by EEG criteria.
MRI findings showed significant changes in the size of certain
brain structures in people who had histories of abuse. The most
striking finding was a decrease in the size of the left
hippocampus, a structure responsible for storing new memories
and which is connected to the limbic system, which regulates
emotions. Another finding was a decrease in the size of the
middle part of the corpus callosum, which contains the circuits
that enable the two sides of the brain to communicate.
Functional imaging techniques looked at which parts of the
brain "lit up" when subjects thought about disturbing memories
and when they thought about emotionally neutral memories. In
people with abuse histories, the right side of the brain appeared
most active when processing emotional memories, while the left
side was most involved in recalling neutral memories. People
without such histories appeared to recruit both sides of the
brain simultaneously in processing both emotional memories and
neutral memories.
Do these studies demonstrate that childhood abuse and neglect
cause permanent, unique, and irreparable harm to the developing
brain? Perhaps, but they must be viewed in the light of studies
of other conditions and in the light of what we know about the
plasticity (changeability) of the structures in question.
Studies of adult patients with clinical depression have found
that the left hippocampus of depressed people is significantly
smaller than normal. One study found a 19% decrease in the size
of the left hippocampus in depression, greater in magnitude
than the decrease found in abused adults. In depression, at
least, there is evidence that this "shrinkage" is reversible
with certain antidepressant medications. It is not yet clear
whether or not it is also reversible when recovery from
depression occurs via psychotherapy alone.
How could damage to an organ that cannot repair itself be
reversible? First, it is too simplistic to assume that a change
in the size of a structure on an X-ray necessarily means that
the structure has been damaged. Tissue studies in some depressed
patients with decreased hippocampal volume failed to show
significant numbers of dying cells. It remains possible that
the changes in volume resulted from reversible changes in the
shape of cells or in their geometric arrangement. Second, while
much of the brain is incapable of generating new neurons beyond
birth, the hippocampus is an exception, still capable of growing
new functional nerve cells perhaps well into adult life. This
structure can indeed repair itself.
Decreased size of the hippocampus is therefore not a unique
finding in people with histories of abuse. It may, in fact, be
a relatively common finding in many stress-related conditions.
There is evidence that the hormones that the body produces in
response to stress tend to reduce the size of the hippocampus.
We may discover in time that this structure varies in size
throughout life, shrinking in response to stress and recovering
in size once stressful conditions have been relieved.
The altered relationship between the functions of the left
and right hemisphere is most interesting. Normally, there appears
to be a balance maintained between the functions of the two sides
of the brain. We learned long ago by observing the effects of
strokes, which damage specific parts of the brain, that the right
hemisphere is associated with intense, often negative emotions,
and that the left hemisphere tends to modulate these emotions.
If the frontal lobe of the left hemisphere is damaged by a
stroke, patients often become deeply depressed, reacting as though
an overwhelming catastrophe has befallen them. If the damage is
in the right hemisphere, patients are often indifferent to their
plight, which may be physically just as serious as that of the
left hemisphere stroke victims. In fact, some may even fail to
recognize that their bodies are malfunctioning.
If abuse victims have somehow learned to respond to some
situations with their left brain and others with their right
brain, one consequence might be alternating between periods
of intensely painful emotions and periods of relative emotional
numbness, much as we see in BPD. So the model fits, but is the
malfunction permanent or reversible?
If this altered organization of brain function could be
repaired, the endpoint would be a restoration of the normal
balance between the hemispheres so that both sides respond
together to any mental task. Eye Movement Desensitization and
Reprocessing (EMDR), a treatment developed for the treatment
of trauma, combines mental imagery with side-to-side rhythmic
eye movements. One possible explanation of the power of this
technique is that the side-to-side eye movements cause the
left and right hemispheres to be alternately activated,
bringing both sides of the brain to bear in processing memories
that may have been stuck primary in one (presumably the right)
hemisphere. EMDR may therefore be a means of reintegrating the
functions of the hemispheres particularly in relation to
previously traumatic memories. Perhaps functional brain imaging
studies will eventually support this theory.
In summary, the findings of structural and EEG abnormalities
in victims of abuse are probably valid and will likely be
reproduced. These findings, however, may not be unique to this
population, but may turn up in a variety of stress-associated
conditions. The abnormalities, while impressive, may be reversible
with both pharmacological and psychotherapeutic interventions.
The brain is more plastic than we once believed. And we know
that treatment can bring recovery both from BPD and from
Post-Traumatic Stress Disorder.
© Dr. Richard Moskovitz
as of March 21, 2002
