by Henry Llewen
A RESEARCH team at the Craig Dunain hospital in Inverness, eastern
Scotland, have developed a simple skin test which they believe will
help doctors with the diagnosis and treatment of schizophrenia.
The test uses a plastic strip impregnated with a chemical derivative
of the B vitamin niacin. This causes a reddening of the skin in
normal people which is significantly reduced in schizophrenics. The
test should make it possible to distinguish schizophrenia from other
conditions at an early stage, so the right treatment can be given.
As one of the research team, Pauline Ward, explains, the test was
developed as a result of observations made over 20 years ago: "The
observations were made when doctors were attempting to treat
schizophrenia with large doses of vitamins. It was noted that,
whereas when you give normal people large doses of the vitamin niacin
they tend to flush quite considerably, on their bodies and faces, the
schizophrenics didn't do that.
"It was suggested then that this might be an indication of abnormal
biochemistry in schizophrenia. But it has only been recently that we
set out to discover what the actual mechanism is."
It became clear that the reaction seen more strongly in
non-schizophrenics is a reaction by cells, macrophages in the skin,
which release the locally acting hormone prostaglandin D2 on exposure
to niacin. This causes nearby blood vessels to dilate, causing
reddening of the skin.
The theory developed to explain the lessening of this effect in
schizophrenics is that, as other research has shown, their blood
cells produce less arachidonic acid, which is required for the
synthesis of prostaglandins.
Pauline Ward and her colleagues decided to develop a simple skin test
measuring this effect, which could easily be used to see how
significant were differences between schizophrenics and
non-schizophrenics, and which could be used clinically if the
differences proved significant.
Trials of the skin test began about two years ago. The test used a
plastic strip with absorbent paper patches on it. The patches
contained four different dilutions of aqueous methyl nicotinate, a
derivative of niacin. The strips were placed on the skins of test
subjects for five minutes, and the colour change reaction measured
over the following 15 minutes.
The tests were carried out on 38 schizophrenic patients and 22 normal
controls. Pauline Ward said: "We found highly significant differences
between the schizophrenics and the normal controls at all four
concentrations of methyl nicotinate. All the schizophrenics were less
reactive than the controls."
More extensive trials will be required before the test can be used
routinely in clinical medicine. Research is needed to discover at
exactly what stage in the onset of schizophrenia the test becomes
valid, and what results it gives in other affective disorders
(serious mental illnesses.)
The Highland Psychiatric Research Group, that has carried out the
work, also intends in future studies to stimulate the skins of
schizophrenic patients and controls directly with prostaglandin D, to
see if the blockage is at the niacin-macrophage level or at another
stage of the pathway.
The test will undoubtedly be valuable in defining a biochemically
distinct group, of people with low levels of arachidonic acid,
probably as a result of abnormal activity of the enzyme phospholipase
A2, increased activity of which has been reported in platelets and
serum from schizophrenics, and which may be responsible for increased
breakdown of phospholipids in the cell membranes of brain cells in
the cerebral cortex of schizophrenics, causing abnormalities in
When it has been refined Pauline Ward and her colleagues hope the
test will be valuable clinically. "I see it being used initially as an
aid to diagnosis, because often when it first presents in a young
person it's hard to distinguish schizophrenia from the effects of
drugs or straightforward depression," she added.
"It should be useful there. It may also be useful in monitoring the
effects of treatment, especially new medications which use diet to
attempt to correct abnormalities in brain cell membranes."
For more information contact:
Highland Psychiatric Research Group
Craig Dunain Hospital
Inverness, United Kingdom, IV3 6JU
Telephone: +44 1463 704660
Fax: +44 1463 718863