Diagnosing
Schizophrenia
with a Blood Test
Israeli
researchers may have found a way to diagnose schizophrenia by analyzing white
blood cells for signs of a chemical that is overactive in patients with the
psychiatric condition. Psychiatrists may be able to give patients a simple
blood test to determine at an early stage whether a patient has the disorder
instead of observing behavior for at least six months before diagnosing and
treating it. The blood test, which has been patented but is not likely to
be commercially available for several years, was proposed and tried on patients
by Professor Sara Fuchs of the immunology department of the Weizmann Institute
of Science in Rehovot and by graduate student Tal Ilani.
Their study, carried out with help from colleagues at the
Rambam Hospital in Haifa and nearby Be’r Ya’acov and Tirat Hacarmel mental
health centers, appears in the Jan 16, 2001 Proceedings of the National Academy
of Sciences of the USA.
The test could eventually lead to the development of better
drugs for managing schizophrenia. Numerous research findings, said
Professor Fuchs, suggest a possible connection between the disease and an
excessive activity of dopamine. This activity is dependent, among other
factors, on the number of dopamine receptors on the surface of nerve cells.
In fact, postmortem studies of the brains of schizophrenia patients, as well as
positive emission tomography of the brains of live patients, have suggested that
the number of these receptors is increased in schizophrenia.
Unfortunately, it is impossible to access the number and location of dopamine
receptors in the brains of live schizophrenia patients with adequate precision.
Professor Fuchs and her coauthors suggested that the way to get around this
problem is to evaluate the presence of dopamine receptors on the surface of
lymphocytes. The researchers thus compared blood samples taken from people
with schizophrenia in local psychiatric hospitals with samples taken from
healthy people. As identifying dopamine receptors on the surface of white
blood cells is very difficult, the scientists focused on an earlier stage in
receptor formation, the stage at which messenger RNA (mRNA) molecules in the
cells convey the generic information needed for making dopamine receptors from
the cell nucleus to the ribosome, the small cellular “factory” where
receptors are manufactured. A statistical analysis showed that the blood
of patients with schizophrenia contains on average 3.6 times more mRNA molecules
of dopamine receptors of a particular kind (D3) than the blood of healthy
people. The high levels were observed in patients treated with various
drugs as well as those who received no drugs. The scientists proposed
using the blood test determining the levels of mRNA that encode D3 receptor of
the membranes of white blood cells as a test for schizophrenia.
Professor Avi Weizman, a psychiatrist and researcher at
Israel’s Geha psychiatric hospital who has followed the Weizmann Institute’s
research, called the findings a breakthrough that could lead to the development
of more receptor specific drugs with fewer side effects. “The research
is very important, not only because it makes objective and early diagnosis
realistic, but it stresses the biological nature of schizophrenia and thus will
help reduce the public stigma of the disease. “The test has to be tried
on a larger number of patients – both treated and untreated – to show that
it is reproducible in all of them,” he said.
- NAMI
Sacramento Newsletter, March 2001
-
Click here for the
original article by Ilani,
Ben-Shachar, Strous, Mazor,
Sheinkman, Kotler, and Fuchs; A peripheral marker for schizophrenia: Increased levels of D3
dopamine receptor mRNA in blood lymphocytes PNAS 98(2), Jan 16, 2001, 625-628.
