Bacteria, viruses and parasites may cause mental illnesses

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Newsweek

 

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.

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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.