The
niacin skin phenomenon reflects a
prostaglandin (PG) mediated flush and oedema reaction. As PG metabolism is linked to breakdown of
membrane lipids, diminished sensitivity to
niacin application suggests potential disturbance in membrane
phospholipid-
arachidonic acid-PG pathways. We aimed to evaluate and quantify topical
niacin skin reaction in early
psychosis using optical reflection spectroscopy (
ORS) and a new descriptive assessment scale integrating time course, redness, and oedema.
Niacin skin tests were performed on 25 medicated first-episode
psychosis patients fulfilling DSM-IV criteria for schizophreniform
psychosis or
schizophrenia and on 25 healthy controls.
Nicotinic acid was applied in four dilution steps to the subjects inner forearm skin and skin reaction was consecutively assessed using
ORS and a seven point rating scale. Both descriptive ratings and spectroscopic measures revealed significant group differences at the lower
niacin concentrations (0.001 and 0.0001 M). At higher concentrations (0.01 and 0.1 M) only descriptive ratings were capable to show significant group effects. Data of both methods showed moderate to strong correlation (r=0.605) as long as the
erythema was not affected by the oedema. The data suggest that
niacin sensitivity is inversely correlated with negative symptoms. Both methods demonstrate that
niacin sensitivity is impaired in a group of first episode
psychosis patients and are therefore able to distinguish a subgroup of patients with metabolic impairment.
Niacin sensitivity in high risk populations and the specificity of impaired skin response are subjects of further investigation.