40
&
January 2016 | Read this issue and more at www.healthandwellnessmagazine.net |
Could Depression Be Caused by
an Infection or Inflammation?
Researchers still trying to prove connection
By Angela S. Hoover, Staff Writer
In the beginning of the 20th century, it was proposed that psychiatric
illness was the result of chronic infection. Adolph Meyer of John Hopkins
Medical School popularized and
taught this theory. Around 1907,
one of his former students, Henry
Cotton, began extracting his patients’
teeth, tonsils, testicles, ovaries and
even colons at the New Jersey State
Hospital for the Insane in an effort to
cure them.
Though not well known today,
Cotton gained prestige and accolades
in his day. His 1921 book, “The
Defective Delinquent and Insane:
The Relation of Focal Infections
to Their Causation, Treatment and
Prevention,” was well received by
“eminent physicians and surgeons,”
according to The New York Times.
Cotton went on to run a successful
private practice for the high society
circles in Trenton, N.J. But after
his death in 1933, interest in his
cures dissipated, due to his patients’
mortality rates only being around
45 percent. And while it is likely his
barbaric treatments did no more than
disfigure and further traumatize his
patients, there just may be something
to the belief that infection – and with
it, inflammation – may be involved in
some forms of mental illness.
A paper published in the journal Biology of Mood and Anxiety
Disorders late last year asserted
depression should be thought of as
an infectious disease. “Depressed
patients act physically sick,” Turhan
Canli wrote. “They’re tired; they lose
their appetite; they don’t want to get
out of bed. The idea that depression
is caused simply by changes in serotonin is not panning out. We need to
think about other possible causes and
treatments for psychiatric disorders.”
Canli noted how certain infections of the brain, most notably
Toxoplasma gondii, can result in
emotional disturbances that mimic
psychiatric conditions. He also said
numerous pathogens have been associated with mental illnesses, such as
Borna disease virus, Epstein-Barr and
certain strains of herpes, including
varicella zoster, the virus that causes
chicken pox and shingles. Canli
believes the pathogens acting directly
on the brain may result in psychiatric
symptoms and also that autoimmune
activity triggered by infection may
also contribute.
In a Danish study published in an
issue of JAMA Psychiatry in 2013,
researchers studied the medical
records of more than 3 million people. They found those with a history
of hospitalization for infection had
a 62-percent increased risk of later
developing a mood disorder, including depression and bipolar disorder.
The study also reported a past history
of an autoimmune disorder increased
the risk of a future disorder by 45
percent.
The Antibodies of the Immune
System
Autoantibodies were first reported
in schizophrenic patients in the
1930s. Further research has detected
antibodies with various neurotransmitter receptors in the brains of
psychiatric patients, and a number of
brain disorders, including multiple
sclerosis, are known to involve abnormal immune system activity.
Researchers at the University of
Virginia recently identified a previously unknown network of vessels
directly connecting the brain with the
immune system. They concluded the
relationship between the two could
significantly contribute to certain
neurologic and psychiatric conditions.
Infection and autoimmune activity
result in inflammation, and multiple
studies have linked depression with
elevated inflammation markers.
However, to date, the research
only finds associations and does
not yet prove cause and effect
between inflammation and mental health.
The “immune-inflammatory
system” is at the core of mental
illness, and psychiatric disorders
may be an unfortunate cost of our
powerful immune defenses, says
Dr. Roger McIntyre, a professor
of psychiatry and pharmacology
at the University of Toronto. “Our
immune-inflammatory system doesn’t
distinguish between what’s provoking
it,” McIntyre said. Stressors of any
kind – physical or sexual abuse, sleep
deprivation, grief, etc. – can activate
the immune system’s response.
“For reasons other than fighting
infection, our immune-inflammatory
response can stay activated for weeks,
months or years and result in collateral damage,” McIntyre said.
He implicated inflammation in
general – not inflammation caused
by infection or as a direct effect of
infection itself – as a major contributor to mental disorders. “It’s unlikely
that most people with a mental illness
have it as a result of infection,” he
said. “But it would be reasonable to
hypothesize that a subpopulation of
people with depression or bipolar disorder or schizophrenia ended up that
way because an infection activated
their immune-inflammatory system.”
Infection, particularly in the womb,
could work in tandem with genetics,
psychosocial factors and one’s diet
and microbiome to influence immune
and inflammatory activity and, in
turn, increase the risk of psychiatric
disease, according to McIntyre.
This past November, new research
claimed inflammation is causing
depression in about one-third of
patients. Researchers at Emory
University in Georgia have found
high levels of inflammation are associated with a “failure to communicate”
between two parts of the
brain,
Like us
@healthykentucky
the ventral striatum and the
ventromedial prefrontal cortex.
Additionally, they found about
one-third of people diagnosed with
depression have markers of elevated
inflammation levels in their blood.
The findings also suggest chronic
inflammation can affect the brain in
ways that are connected w ]