Bacteria, viruses and parasites may cause mental illnesses like depression

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Diseases of the Mind

Bacteria, viruses and parasites may cause mental illnesses like
depression
and perhaps even autism and anorexia

By Janet Ginsburg

Newsweek International

Dec. 1 issue - Olga Skipko has had the good fortune to live most of her
adult life in the Polish village of Gruszki, in the heart of the
Puszcza
Bialowieska, one of Europe's most beautiful forests and home to wolves,
lynxes and the endangered European bison. Unfortunately, the forest is
also
a breeding ground for disease-carrying ticks. Skipko, 49, thinks she
was
bitten about 10 years ago, when she began having the classic symptoms
of
Lyme borreliosis, a tickborne nervous-system disease: headaches and
aching
joints. She didn't get treatment until 1998. "I was treated with
antibiotics
and felt a bit better," she says.

That was only the beginning of her troubles. A few years later, she
began to
forget things and her speaking grew labored. It got so bad that she had
to
quit her job in a nursery forest and check herself in to a psychiatric
clinic. "I hope they will help me," she says. "I promised my children
that
when I come back home, I will be able to do my favorite crosswords
again."
Doctors ran a battery of tests and concluded that her mental problems
were
the advanced stage of the Lyme disease she had contracted years ago.

Scientists have long known that some diseases can cause behavioral
problems.
When penicillin was first used to treat syphilis, thousands of cured
schizophrenics were released from mental asylums. Now, however,
scientists
have evidence that infections may play a far bigger role in mental
illness
than previously thought. They've linked cases of obsessive-compulsive
disorder, bipolar disorder and schizophrenia to a variety of infectious
agents, and they're investigating autism, Tourette's and anorexia as
well.
They're beginning to suspect that bad bugs may cause a great many other
mental disorders, too. "The irony is that people talked about syphilis
as
the 'great imitator'," says University of Louisville biologist Paul
Ewald,
"but it may be the 'great illustrator'-a model for understanding the
causes
of chronic diseases."

Mental illnesses constitute a large and growing portion of the world's
health problems. According to the World Health Organization, depression
is
one of the most debilitating of diseases, on a par with paraplegia.
Psychiatric illnesses make up more than 10 percent of the world's
"disease
burden" (a measure of how debilitating a disease is), and are expected
to
increase to 15 percent by 2020. Much of this may be the work of
viruses,
bacteria and parasites. Psychiatrist E. Fuller Torrey, of the Stanley
Medical Research Institute in Maryland, has found from studying
historical
asylum records that hot spots-higher-than-normal incidences-of mental
illness can shift, much like infectious-disease outbreaks, which lends
credence to the notion that infectious agents play a big role. "Mental
disorders are the major chronic recurrent disorders of youth in all
developed countries," says Harvard policy expert Ronald Kessler, who
directs
the WHO's mental-health surveys.

Perhaps the most well known disease that's been linked to mental
disorders
is Lyme disease, which is caused by the Borrelia burgdorferi germ.
First
identified in the mid-1970s among children near Lyme, Connecticut, the
disease has long been known to cause nervous-system problems and achy
joints
if left untreated. Now scientists are finding that Lyme disease can
also
trigger a whole smorgasbord of psychiatric symptoms, including
depression.
One New York man (we'll call him Joe) found out firsthand how
debilitating
the disease can be. When he began having bouts of major depression back
in
1992, he had forgotten all about the tick bite he had gotten four years
earlier. He spent two years in a blur of antipsychotic drugs, mental
institutions, jails and suicide attempts. On a hunch, a doctor at a
psychiatric hospital in New Jersey had Joe tested for Lyme disease.
After an
intensive course of antibiotics, Joe's improvement was dramatic and
immediate. "I started to have this fog lift," he recalls. Still, he
will
probably have to be on psychotropic drugs for the rest of his life.

Some psychiatrists fret that there may be thousands of people suffering
from
Lyme-induced depression without knowing why. Not only is Lyme disease
tricky
to diagnose-not everybody gets the circular rash, and lab tests still
aren't
wholly reliable-it can take a decade or more for mental disorders to
set in.
The U.S. Centers for Disease Control says that nine out of 10 cases of
Lyme
diseases remain unreported. There are 15 species of borellias-making
them
the most common tickborne disease-producing bacteria in the world.

For its part, the parasite Toxoplasma gondii, which can be found in
undercooked meat and cat feces, can lead to full-blown psychotic
episodes.
Some studies suggest that the parasite stimulates the production of a
chemical similar to LSD, producing hallucinations and psychosis. Even
when
the parasite lies dormant in muscle and brain tissue, it can affect
attention span and reaction time in otherwise healthy people.
Researchers at
Charles University in Prague have discovered that people who test
positive
have slightly slower-than-average reaction times and-possibly as a
result-are almost three times as likely to have car accidents. That's a
disturbing prospect, considering that the disease is so widespread:
billions
of people are thought to be infected.

Even a simple sore throat can lead to psychiatric problems. Few
children
avoid coming down with a streptococcus infection, also known as strep.
Scientists now think that one in 1,000 strep sufferers also develops
abrupt-onset obsessive-compulsive disorder (OCD) in a matter of weeks.
Strep
bacteria trigger OCD by igniting an overzealous response from the
immune
system, which attacks certain types of brain cells, causing
inflammation.
Symptoms generally die down after a few months but can flare up again,
especially if there's another bout of strep, says Susan Swedo, a
childhood-disease expert at the National Institutes of Health. The most
effective treatment, still experimental, is to filter out the
misbehaving
antibodies from the blood. Best is to treat strep early on.

The specter of a depression germ or contagious obsessive-compulsive
disorder
is unnerving, but it also opens up many more treatment
options-antibiotics,
vaccines, checking for ticks. Geneticists believe that diseases may
trigger
the onset of inherited mental illnesses by activating key genes.
Avoiding
and treating infection may be just as important as the genes you
inherit,
and a whole lot easier to do something about.

----------------------------------------------------------

With Joanna Kowalska In Warsaw

© 2006 Newsweek, Inc.

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