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   A simple skin patch may soon help doctors identify people with
schizophrenia, it was claimed today.
   The "niacin skin flush test" consists of a plastic strip impregnated
with a derivative of the B vitamin niacin.
   When placed on a healthy person, it causes the blood vessels to dilate
and turns the skin red. But the skin of someone with schizophrenia reacts
much more weakly.
   Pauline Ward and colleagues at the Craig Dunain Hospital in Inverness
tested the strip on 38 schizophrenics and 22 healthy volunteers, New
Scientist magazine reported.
   They found that 83% of the schizophrenics had almost no redness while
only 23% of the others failed to react.
   The number of false positives and negatives is still too high for the
strip to be used as a diagnostic tool. But the researchers believe it can
be refined.
   "We are still playing about with the dilutions and exposure times," Ward
told New Scientist.
   The flushing response to niacin depends on the release of a compound
derived from an essential fatty acid in cell membranes.
   Some studies have shown that schizophrenics' cell membranes have reduced
levels of this and other fatty acids.
   Other experts doubt that membrane fatty acids are central to schizophrenia.
   Robert Kenwin, of the Institute of Psychiatry in London, said: "It's not
getting at the major biochemical abnormalities."
   The findings are due to appear in a future issue of the journal Schizophrenia Research.