A first quick note is that this is likely one of several causes of schizophrenia and other associated mental illness. However, it appears consistent to assert that clinical mental illness is primarily caused by micro damage to the physical structure of the brain itself.
We already have this well confirmed in the many cases of sports related brain trauma and hardly need more Mohammed Ali’s to watch on their lonely trip to the grave.
It is noteworthy that head shocks are related to the onset of the symptoms of manic depression, particularly if there are two such events close in time before the first has fully healed.
In the end, we may simply have to end any form of head contact in sports, or at least make changes that take such events out of the normal flow.
Here we have identified a biological agent that penetrates the brain and generates cysts.
This also provides causation for classes of low level mental illnesses were rational behavior is not consistent at all. Victims may be able to function in a disciplined environment such as the work place, but turn the lives of family upside down through erratic decisions when faced with new choices.
It is plausible that there are other similar causation agents out there, but cats have been on the top of the list for a long time.
We need to clean the problem out of domestic cats and such animals need to be prevented from hunting. Otherwise they are likely safe on farms in which they defecate out of doors so that dried fecal matter does not get into the atmosphere.
Cat parasite may cause mental illness
Scientists look for a link between infections and brain disorders such as schizophrenia
BY FRANK D. ROYLANCE, VANCOUVER
The researchers say the microbes, called Toxoplasma gondii, invade the human brain and appear to upset its chemistry -- creating, in some people, the psychotic behaviours recognized as schizophrenia.
If tackling the parasite can help solve the mystery of schizophrenia, "it's a pretty good opportunity ... to relieve a pretty large burden of disease," said Dr. Robert H. Yolken, director of developmental neurobiology at the Johns Hopkins
The cause of schizophrenia is unknown, but both genetic and environmental factors likely play a part, according to the U.S. National Institute of Mental Health.
Yolken is among the researchers worldwide examining whether certain infections can increase the risk of developing the illness. Other studies have focused on flu and herpes viruses as possible triggers.
The notion that there are links between infections and schizophrenia is "intriguing," said Dr. Ken Duckworth, a clinical psychiatrist and medical director for the U.S. National Alliance
"There's so much we don't know about schizophrenia that anybody paying attention would welcome any thoughtful inquiry. And the infectious disease corner of the field is a growth stock right now," he said. "If true, it would have a preventive implication which is profound."
Hygienic precautions
In a study of 12-to 49-yearolds who were born in the U.S. , about nine per cent were found to be infected with T. gondii in the early 2000s, according to the U.S.
Yolken, a cat owner who says he has tested positive for Toxoplasma antibodies, said the potential link between Toxoplasma infections and mental illness is no reason for cat owners to panic -- they just need to keep some basic hygienic precautions in mind.
He was drawn into the field by some intriguing questions about schizophrenia.
"I couldn't understand why a disease like schizophrenia persists in humans," he said.
Through much of our history, "people who have these diseases don't reproduce very well, either because they're sick, or they've been locked up, or because they were killed."
If the disorder were strictly genetic in origin, he added, those genes should have been culled from the gene pool long ago. But they weren't.
That raises the question of an environmental, perhaps infectious origin -- a germ that has evolved to benefit by infecting other species.
It was a colleague, Dr. E. Fuller Torrey of the Stanley Medical Research Institute in Chevy Chase, Md., who sealed the deal for Yolken by unearthing a trove of studies from as far back as the 1950s, many of them not written in English, suggesting links between infections and schizophrenia.
Schizophrenia, a severely disabling brain disorder characterized by confusion, delusions and hallucinations, afflicts 1.1 per cent of North Americans aged 18 and older, according to the U.S. National Institute of Mental Health.
Lifelong infection
Someone with a toxoplasma infection, called toxoplasmosis, is more than twice as likely to develop schizophrenia, according to Yolken.
First isolated in 1908, T. gondii is present in the bodies of a third of the world's population, on average. It is a lifelong infection.
"Humans can get infected either directly [from contact with cat feces], or from eating the [undercooked] meat of an animal that was itself infected by a cat," Yolken said. Some toxoplasmosis outbreaks have been traced to water supplies contaminated by cat feces.
When they're initially infected, most people have little more than flu-like symptoms, or none at all. Young children, people with weakened immune systems and women infected while pregnant can develop a brain inflammation called encephalitis, or suffer miscarriages, damage to the heart, liver, eyes or ear, or even die.
Felines are typically infected when they eat an infected mouse or bird. They don't usually get sick. So far, there is no vaccine to prevent cats from becoming infected. So the microbe reproduces in the cat's gut. Its eggs, or oocysts, develop there, and are later shed with the cat's feces.
When another warm-blooded animal such as a mouse ingests the oocysts through contact with cat feces, the oocysts enter its gut.
There they release cells that migrate mostly to muscles and the brain, forming cysts to protect themselves from the mouse's immune system.
But T. gondii must get back into a cat to reproduce again. To get there, it needs the mouse to be eaten by a cat.
Scientists believe the parasite raises its odds of success by changing the mouse's behaviour and reversing its natural fear of cats. But how?
Studies of mice and rats infected by T. gondii have shown risky behaviour changes, including an attraction to the smell of cat urine that makes them vulnerable to attacks. These findings may have parallels in behavioural changes in people, from schizophrenia to depression and reflex impairment.
'Unusual' enzyme
Glenn McConkey, a researcher at the University of Leeds in England, reported last year that two genes in T. gondii's DNA contain instructions for the production of an enzyme that makes a brain chemical called dopamine.
"That's somewhat unusual, because other parasites don't have that [dopamine]," said Sarven Sabunciyan, Yolken's colleague at Hopkins
In higher animals with nervous systems, dopamine is a neurotransmitter with important roles in regulating behaviour. Some anti-psychotic drugs used to treat schizophrenia work by blocking dopamine action in the brain.
Medical students have long been told that mental illness and infectious disease were separate fields.
"I was taught they had nothing to do with each other," said Duckworth. But then he'd encounter a Lyme disease patient with something resembling psychosis, or an AIDS patient with depressive symptoms.
"I think it's intuitively possible. After my experience with AIDS patients, I can think, 'Why not?' "
Evidence that T. gondii infections may be a cause of schizophrenia, while not yet conclusive, is growing, Yolken said. A review of past studies, published last year by Yolken and Torrey, collected a variety of intriguing correlations.
For example: People with schizophrenia have a higher prevalence of T. gondii antibodies in their blood. There are unusually low rates of schizophrenia and toxoplasmosis in countries where cats are rare, and unusually high rates in places where eating uncooked meat is customary. And some adults with toxoplasmosis show psychotic symptoms similar to schizophrenia.
Cysts are active
Studies have linked a history of toxoplasmosis with increased rates of other mental changes, too, including bipolar disorders and depression.
Yolken believes additional factors, such as an unlucky combination of genes, are probably needed to produce schizophrenia among Toxoplasmainfected people. The parasite's DNA also may be important, since some strains are known to cause more disease.
Studies also have suggested that the timing of the infection -- early in life when the brain is developing -- and the place in the brain where the cysts settle, may be important, he said.
But once the T. gondii cysts are established, how might medical science find and kill, or at least silence them?
Yolken said that while T. gondii cysts are invisible to the immune system, they are not totally passive. Inside the cysts, the microbes are alive, sensing their environment, periodically trying to break out, multiply and form more dopamine-making cysts. The flare-ups probably occur when the host's immune system is weakened by illness or stress.
Scientists believe these "reactivations" of the infection could explain the emergence or worsening of cognitive symptoms as people with schizophrenia reach adolescence and young adulthood.
Researchers also have noted that toxoplasmosis is similar to malaria in its persistence in the body, its flare-ups, and its ability to hide from the immune system, Yolken said. So Sabunciyan and researchers elsewhere are investigating whether anti-malarial drugs might work against T. gondii cysts.
Sabunciyan has reported promising results with a class of anti-malarial drugs, called artemisinins, which appear to be effective at killing T. gondii in tissue cultures. "The next step is to do that in animals," Yolken said.
If it works in animals, that would raise hopes for a toxoplasmosis treatment for people, and perhaps, one day, some relief for people with schizophrenia.
Researchers explore link between schizophrenia, cat parasite
The researchers say the microbes, called Toxoplasma gondii, invade the human brain and appear to upset its chemistry _ creating, in some people, the psychotic behaviors recognized as schizophrenia.
If tackling the parasite can help solve the mystery of schizophrenia, "it's a pretty good opportunity ... to relieve a pretty large burden of disease," said Dr. Robert H. Yolken, director of developmental neurobiology at the Johns Hopkins
The cause of schizophrenia is unknown, but both genetic and environmental factors likely play a part, according to the National Institute of Mental Health. Yolken is among the researchers worldwide examining whether certain viral infections can increase the risk of developing the illness. Other studies have focused on flu and herpes viruses as possible triggers.
The notion that there are links between infections and schizophrenia is "intriguing," said Dr. Ken Duckworth, a clinical psychiatrist and medical director for the National Alliance
In a study of 12- to 49-year-olds who were born in the U.S.
Yolken, a cat owner who says he has tested positive for Toxoplasma antibodies, said the potential link between Toxoplasma infections and mental illness is no reason for cat owners to panic _ they just need to keep some basic hygienic precautions in mind.
He was drawn into the field by some intriguing questions about schizophrenia.
"I couldn't understand why a disease like schizophrenia persists in humans," he said. Through much of our history, "people who have these diseases don't reproduce very well, either because they're sick, or they've been locked up, or because they were killed."
If the disorder were strictly genetic in origin, he added, those genes should have been culled from the gene pool long ago. But they weren't. That raises the question of an environmental, perhaps infectious origin _ a germ that has evolved to benefit by infecting other species.
It was a colleague, Dr. E. Fuller Torrey of the Stanley Medical Research Institute in Chevy Chase, who sealed the deal for Yolken by unearthing a trove of studies from as far back as the 1950s, many of them not written in English, suggesting links between infections and schizophrenia.
Schizophrenia, a severely disabling brain disorder characterized by confusion, delusions and hallucinations, afflicts 1.1 percent of the U.S. population age 18 and older, according to the National Institute of Mental Health. Someone with a toxoplasma infection, called toxoplasmosis, is more than twice as likely to develop schizophrenia, according to Yolken.
First isolated in 1908, T. gondii is present in the bodies of a third of the world's population, on average. It is a lifelong infection.
"Humans can get infected either directly (from contact with cat feces), or from eating the (undercooked) meat of an animal that was itself infected by a cat," Yolken said. Some toxoplasmosis outbreaks have been traced to water supplies contaminated by cat feces.
When they're initially infected, most people have little more than flulike symptoms, or none at all. But young children, people with weakened immune systems and women infected while pregnant can develop a brain inflammation called encephalitis, or suffer miscarriages, damage to the heart, liver, eyes or ears. Infection can be fatal, and fetuses that survive their mother's first infection may be born with retardation, deafness and other problems.
Felines are typically infected when they eat an infected mouse or bird. They don't usually get sick. So far, there is no vaccine to prevent cats from becoming infected. So the microbe reproduces in the cat's gut. Its eggs, or oocysts, develop there, and are later shed with the cat's feces.
When another warm-blooded animal such as a mouse ingests the oocysts through contact with cat feces, the oocysts enter its gut. There they release cells that migrate mostly to muscles and the brain, forming cysts to protect themselves from the mouse's immune system.
But T. gondii must get back into a cat to reproduce again. To get there, it needs the mouse to be eaten by a cat. Scientists believe the parasite raises its odds of success by changing the mouse's behavior and reversing its natural fear of cats.
But how?
Studies of mice and rats infected by T. gondii have shown risky behavior changes, including an attraction to the smell of cat urine that makes them vulnerable to attacks. These findings may have parallels in behavioral changes in people, from schizophrenia to depression and reflex impairment.
Glenn McConkey, a researcher at the University of Leeds in England, reported last year that two genes in T. gondii's DNA contain instructions for the production of an enzyme that makes a brain chemical called dopamine.
"That's somewhat unusual, because other parasites don't have that (dopamine)," said Sarven Sabunciyan, Yolken's colleague at Hopkins
But in higher animals with nervous systems, dopamine is a neurotransmitter with important roles in regulating behavior. Some anti-psychotic drugs used to treat schizophrenia work by blocking dopamine action in the brain.
Medical students have long been told that mental illness and infectious disease were separate fields.
"I was taught they had nothing to do with each other," said Duckworth, at NAMI. But then he'd encounter a Lyme disease patient with something resembling psychosis, or an AIDS patient with depressive symptoms. "I think it's intuitively possible. After my experience with AIDS patients, I can think, 'Why not?' "
Recent studies have found that a variety of viral infections, early in life, appear to carry risks of brain changes.
In May, Hopkins
Evidence that T. gondii infections may be a cause of schizophrenia, while not yet conclusive, is growing, Yolken said. A review of past studies, published last year by Yolken and Torrey, collected a variety of intriguing correlations. For example: People with schizophrenia have a higher prevalence of T. gondii antibodies in their blood. There are unusually low rates of schizophrenia and toxoplasmosis in countries where cats are rare, and unusually high rates in places where eating uncooked meat is customary. And some adults with toxoplasmosis show psychotic symptoms similar to schizophrenia.
Studies have linked a history of toxoplasmosis with increased rates of other mental changes, too, including bipolar disorders and depression. A 2002 study in the Czech Republic
A University of Maryland
Yolken believes additional factors, such as an unlucky combination of genes, are probably needed to produce schizophrenia among Toxoplasma-infected people. The parasite's DNA may also be important, since some strains are known to cause more disease.
Studies have also suggested that the timing of the infection _ early in life when the brain is developing _ and the place in the brain where the cysts settle, may be important, he said.
But once the T. gondii cysts are established, how might medical science find and kill, or at least silence them?
Yolken said that while T. gondii cysts are invisible to the immune system, they are not totally passive. Inside the cysts, the microbes are alive, sensing their environment, periodically trying to break out, multiply and form more dopamine-making cysts. The flare-ups probably occur when the host's immune system is weakened by illness or stress.
Scientists believe these "reactivations" of the infection could explain the emergence or worsening of cognitive symptoms as people with schizophrenia reach adolescence and young adulthood.
Researchers have also noted that toxoplasmosis is similar to malaria in its persistence in the body, its flare-ups, and its ability to hide from the immune system, Yolken said. So Sabunciyan and researchers elsewhere are investigating whether anti-malarial drugs might work against T. gondii cysts.
Sabunciyan has reported promising results with a class of anti-malarial drugs, called artemisinins, which appear to be effective at killing T. gondii in tissue cultures. "The next step is to do that in animals," Yolken said.
If it works in animals, that would raise hopes for a toxoplasmosis treatment for people, and perhaps, one day, some relief for people with schizophrenia.__
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