Feb. 20, 2004 -- Intriguing early research suggests that people
with a genetic intolerance to gluten may also be at increased risk for schizophrenia.
Investigators say the link, if proven, could lead to new treatment options for
a small subset of schizophrenic people.
Using a Danish health registry, researchers from John's Hopkins
University's Bloomberg School of Public Health found people with the genetic
digestive disorder known as celiac
disease to be three times as likely as the general population to develop
schizophrenia. Lead researcher William W. Eaton, PhD, says the next step is to
determine if following a gluten-free diet makes a difference in the
symptoms of schizophrenic people with celiac disease. He estimates that 3% of
schizophrenic people could potentially benefit from such a diet.
Celiac disease is a lifelong (chronic) condition in which foods
that contain gluten damage the small intestine. Gluten is a form of protein
found in some grains (notably wheat, barley, and rye). The damage to the
intestine makes it hard for the body to absorb nutrients, especially fat,
calcium, iron, and folate, from food.
"We can now screen for celiac disease, so it is at least
conceivable that we can locate the folks with schizophrenia for whom gluten
withdrawal might work," he tells WebMD. "But we still have to do those
Eaton and colleagues examined the medical histories of 7,997
schizophrenics admitted to a Danish psychiatric facility between 1981 and 1998.
For each case they identified 25 people without the mental disorder, matched by
sex and year of birth.
The researchers found no differences in the rates of other digestive
disorders such as Crohn's
disease and ulcerative colitis between the groups, yet people with
schizophrenia were 3.2 times as likely to have a history of celiac disease as
the comparison group. The findings are reported in the Feb. 21 issue of the
British Journal of Medicine.
It is estimated that about 1% of the population of the U.S. has
celiac disease. Eaton says he hopes to identify a group of people with
schizophrenia who also have celiac disease and then put some of them on
gluten-free diets to determine if the intervention is of therapeutic value.
Many Different Causes
He says the latest findings support the growing belief that
schizophrenia has many different causes.
"The thinking is that instead of finding the magic gene or an environmental
influence that is responsible for most cases, we will find dozens and maybe a
hundred causes that each may each explain a small percentage of cases," he
Schizophrenia researcher William T. Carpenter, MD, of the
University of Maryland, says it is now almost certain that no single gene will
be implicated as the cause of the disease. He adds that seven different
genotypes have been linked to schizophrenia so far and others are likely to be
discovered. Carpenter is director of the Maryland Psychiatric Research Center
at the University of Maryland.
The thinking is that genetically susceptible people develop
schizophrenia when they are exposed to certain environmental triggers.
Environmental influences that have been linked to the mental disorder include
pregnancy problems, particularly in the second trimester; difficult delivery;
having a father who is older; and the use of certain recreational drugs.
"For example, you may have a situation where a person has eight
vulnerability genes and their mother had the flu in mid-trimester," Carpenter
tells WebMD. "That double hit just might increase the likelihood of developing
SOURCES: Eaton, W. British Medical Journal, Feb 21, 2004; vol 328: pp
438-439. William W. Eaton, PhD, professor and interim chairman, department of
mental health, Bloomberg School of Public Health, Johns Hopkins University,
Baltimore. William T. Carpenter, MD, director, Maryland Psychiatric Research
Center; department of psychiatry, University of Maryland. WebMD Medical
Reference from Healthwise: "Celiac Disease."