Have you ever wondered what causes clinical depression? Perhaps you have
been diagnosed with major depression, and that's made you question why
some people get depressed while others don't.
Depression is an extremely complex disease. No one knows exactly what
causes it, but it can occur for a variety of reasons. Some people
experience depression during a serious medical illness. Others may have
depression with life changes such as a move or the death of a loved one.
Still others have a family history of depression. Those who do may
experience depression and feel overwhelmed with sadness and loneliness
for no known reason.
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What Are the Main Causes of Depression?
There are a number of factors that may increase the chance of
depression, including the following:
Abuse. Past physical, sexual, or emotional abuse can increase the
vulnerability to clinical depression later in life.
Certain medications. Some drugs, such as isotretinoin (used to treat
acne), the antiviral drug interferon-alpha, and corticosteroids, can
increase your risk of depression.
Conflict. Depression in someone who has the biological vulnerability to
develop depression may result from personal conflicts or disputes with
family members or friends.
Death or a loss. Sadness or grief from the death or loss of a loved one,
though natural, may increase the risk of depression.
Genetics. A family history of depression may increase the risk. It's
thought that depression is a complex trait, meaning that there are
probably many different genes that each exert small effects, rather than
a single gene that contributes to disease risk. The genetics of
depression, like most psychiatric disorders, are not as simple or
straightforward as in purely genetic diseases such as Huntington's
chorea or cystic fibrosis.
Major events. Even good events such as starting a new job, graduating,
or getting married can lead to depression. So can moving, losing a job
or income, getting divorced, or retiring. However, the syndrome of
clinical depression is never just a "normal" response to stressful life
events.
Other personal problems. Problems such as social isolation due to other
mental illnesses or being cast out of a family or social group can
contribute to the risk of developing clinical depression.
Serious illnesses. Sometimes depression co-exists with a major illness
or may be triggered by another medical condition.
Substance abuse. Nearly 30% of people with substance abuse problems also
have major or clinical depression.
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How Is Biology Related to Depression?
Researchers have noted differences in the brains of people who have a
clinical depression as compared to those who do not. For instance, the
hippocampus, a small part of the brain that is vital to the storage of
memories, appears to be smaller in some people with a history of
depression than in those who've never been depressed. A smaller
hippocampus has fewer serotonin receptors. Serotonin is one of many
brain chemicals known as neurotransmitters that allow communication
across circuits that connect different brain regions involved in
processing emotions.
Scientists do not know why the hippocampus may be smaller in some people
with depression. Some researchers have found that the stress hormone
cortisol is produced in excess in depressed people. These investigators
believe that cortisol has a toxic or "shrinking" effect on the
development of hippocampus. Some experts theorize that depressed people
are simply born with a smaller hippocampus and are therefore inclined to
suffer from depression. There are many other brain regions, and pathways
between specific regions, thought to be involved with depression, and
likely, no single brain structure or pathway fully accounts for clinical
depression.
One thing is certain -- depression is a complex illness with many
contributing factors. The latest scans and studies of brain structure
and function suggest that antidepressants can exert what are called "neurotrophic
effects," meaning that they can help sustain nerve cells, prevent them
from dying, and allow them to form stronger connections that withstand
biological stresses. As scientists gain a better understanding of the
causes of depression, health professionals will be able to make better
"tailored" diagnoses and, in turn, prescribe more effective treatment
plans.
How Is Genetics Linked to the Risk of Depression?
We know that depression can sometimes run in families. This suggests
that there's at least a partial genetic link to depression. Children,
siblings, and parents of people with severe depression are somewhat more
likely to suffer from depression than are members of the general
population. Multiple genes interacting with one another in special ways
probably contribute to the various types of depression that run in
families. Yet despite the evidence of a family link to depression, it is
unlikely that there is a single "depression" gene, but rather, many
genes that each contribute small effects toward depression when they
interact with the environment.
Can Certain Drugs Cause Depression
In certain people, drugs may lead to depression. For example,
medications such as barbiturates, benzodiazepines, and the acne drug
isotretinoin (formerly sold as Accutane, now Absorica, Amnesteem,
Claravis, Myorisan, Zenatane) have sometimes been associated with
depression, especially in older people. Likewise, medications such as
corticosteroids, opioids (codeine, morphine), and anticholinergics taken
to relieve stomach cramping can sometimes cause changes and fluctuations
in mood.
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What’s the Link Between Depression and Chronic
Illness?
In some people, a chronic illness causes depression. A chronic illness
is an illness that lasts for a very long time and usually cannot be
cured completely. However, chronic illnesses can often be controlled
through diet, exercise, lifestyle habits, and certain medications. Some
examples of chronic illnesses that may cause depression are diabetes,
heart disease, arthritis, kidney disease, HIV/AIDS, lupus, and multiple
sclerosis (MS). Hypothyroidism may also lead to depressed feelings.
Researchers believe that treating the depression may sometimes also help
the co-existing medical illness improve.
Is Depression Linked to Chronic Pain?
When pain lingers for weeks to months, it's referred to as being
"chronic." Not only does chronic pain hurt, it also disturbs your sleep,
your ability to exercise and be active, your relationships, and your
productivity at work. Can you see how chronic pain may also leave you
feeling sad, isolated, and depressed?
There is help for chronic pain and depression. A multifaceted program of
medicine, psychotherapy, support groups, and more can help you manage
your pain, ease your depression, and get your life back on track.
For in depth information, see Depression and Chronic Pain.
Does Depression Often Occur With Grief?
Grief is a common, normal response to loss. Losses that may lead to
grief include the death or separation of a loved one, loss of a job,
death or loss of a beloved pet, or any number of other changes in life,
such as divorce, becoming an "empty nester," or retirement.
Anyone can experience grief and loss, but not everyone will experience
clinical depression, which differs from grief in that depression
involves a range of other symptoms such as feelings of low self-worth,
negative thoughts about the future, and suicide, whereas grief involves
feelings of emptiness, loss and longing for a loved one, with an intact
capacity to feel pleasure. Each person is unique in how he or she copes
with these feelings. |