| bobwhelan 2004-08-31, 11:11 am |
| Speaking to a cross-section of scientists, doctors, researchers,
students and interested community members, Dr. Huda Akil of the
University of Michigan delivered the keynote address at this year’s
Brain Awareness series sponsored by the Vanderbilt Brain Institute.
Akil’s address, “Brain Biology of Stress and Depression,” provided an
overview of depression and outlined current research and new
developments that could provide help to the millions who agonize
through the “malignant sadness” of depression.
Millions of people wake up every morning to a sense of doom, of
devastating even paralyzing melancholy. Normal stresses can seem
overwhelming, concentrating becomes difficult, and sleeping and eating
behaviors are disturbed. Self-critical and even self-loathing, the
depressed person faces day after day of isolation and despair, looking
down a dark tunnel that seems close and endless.
Despite notable advances, many people still do not understand
depression. Those suffering with the debilitating disease are seen by
some as weak, unable to cope with everyday problems or unwilling to
simply change their attitude. These misconceptions lead many depressed
individuals to live their entire lives trying to mask their illness to
prevent being stereotyped.
Depression is an affective disorder that is extremely common
worldwide. Akil estimates that 10 percent or more of the U.S.
population suffers from it. Women are twice as likely as men are to
develop the disease. The World Health Association has classified it as
the most disabling diagnosis in the world in terms of loss of
productivity and economic and personal loss for the patient and their
family.
In addition to the emotional factors, other more outwardly visible
elements are associated with depression. There are cognitive problems
that impact how a depressed person thinks and processes information,
as well as how they react to stress. The ability to concentrate also
is affected, making it difficult to complete tasks. Physical symptoms
may include problems sleeping, problems eating, and marked fatigue.
Sadly, according to Akil, depression is greatly underdiagnosed and
undertreated, meaning those individuals afflicted by the disorder
often suffer their entire lives without understanding the origins of
the illness, much less that treatment is available. For many years,
depression was treated primarily through verbal counseling,
encouraging the patient to articulate their internal pain. Although
this approach was successful for some, it still failed to truly
address what scientists felt was a deeper disorder with a
physiological, even genetic basis.
Approximately 14 years ago, scientists from fields such as
neurobiology, psychiatry, and neuroscience began studying the biology
of the brain and its impact on emotion with the hope of divining a
physiological basis for depression. Research into this fascinating
field continues. With a greater understanding of what happens in the
brain to cause depression, scientists believe they can develop new
treatments to combat this devastating illness.
Although there is much about the brain and specifically about emotion
that remains a mystery, research has provided insight into the areas
of the brain that control how we handle stress and emotion as well as
genetic links.
Akil, and others in her field, have concluded that depression is a
genetically based disorder. However, not everyone who carries genes
for depression will develop it. Studies have shown a pair of identical
twins who share the same genes may not both develop depression.
Scientists have sought to understand how one of these twins may
struggle with depression throughout their life while the other twin
escapes it. Clearly, there are genes that may make a person vulnerable
but the question remains: why are some people susceptible while others
aren’t?
Although this may be a conundrum for scientists, Akil is encouraged.
“It tells you that genes are not destiny,” Akil said. “Such
discoveries and studies offer hope that depression is not just a fate
into which you’re born.”
Research has also shown that at least the first episode of depression
is triggered by some type of “life event” such as the ending of a
significant relationship, the loss of a job, or death of a close
family member or friend. Once the first depressive episode has
occurred, the person is predisposed to more episodes which may seem to
almost take on a life of their own. Akil discussed research indicating
these episodes could alter the biology of the brain further, a
post-genetic kind of brain plasticity, which increase the likelihood
of future depressive episodes.
There are some genes that may make a person vulnerable, developmental
events and experiential triggers, combining to cause depression. Akil
described this as a “complex genetic disorder,” a convergence of
genetics, biology and environmental factors that can have a
cataclysmic effect on a person’s ability to handle stress and relate
to others.
Akil believes that it is important to understand the neural phenotype,
meaning not just the behavior, not just the genes, but the brain as
the intermediary where everything happens. Both experience and genes
can alter the circuits of the brain and the expression of the genes.
In the case of the identical twins, although they were born with the
same genes, the variances in the way the genes are expressed as well
as the different life experiences can trigger depression and cause
physiological changes to the depressed twin’s brain with each
depressive episode.
When research on the neurological causes of depression began,
scientists were interested in endocrinology and the stress hormones in
the body and how they affected emotional response. This research led
to a greater understanding of the stress circuits and the brain,
specifically the limbic system. Akil and her colleagues feel that the
limbic system may be where depression starts, but also see it as
providing clues to particular molecules that are active in the stress
circuitry of the brain. Through imaging techniques such as MRIs, PET
imaging, and neuroimaging, scientists are discovering more about the
role of the limbic system and how drug treatment can target areas that
are affected by the disease.
Microarray technology is one of the newer approaches to understanding
the genetic basis for individual differences in emotional
responsiveness. Microarray, or gene chip technology, allows scientists
to study the complex genetic basis for emotional behavior. Researchers
can simultaneously examine many thousands of genes to elucidate
individual variations in emotional responses. These studies are
promising, allowing scientists to discover which patterns of gene
expression lead to particular neuronal phenotypes, resulting in
particular behavioral profile such as high responsiveness to stress or
the manifestation of severe depression.
The research of the last two decades has given the medical community a
stronger understanding of depression and its causes. Akil and others
have provided insight to the biological basis of emotional behavior
through the study of the brain circuits that underlie stress. Such
advances offer not only education to reduce the stigma of the disease,
but also offer hope for effective drug treatments that will give the
many sufferers of depression a light at the end of the tunnel.
bobwhelan
"Studies have found that after 3 months of antidepressant
treatment between 50% and 65% of the people who take them
will be much improved. This compares
with 25 - 30% of people given an inactive "dummy" pill,
or placebo."
- The British Journal of Psychiatry
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