Derivatives of neuraminic acid1,2 (or sialic acids) are widely distributed in tissues. In brain, neuraminic acid is found in especially high concentration in gray matter,3,4 the pineal body,5 and the hypophysis.6 As a component of gangliosides, N-acetylneuraminic acid accumulates in the brains of patients with infantile amaurotic familial idiocy.7,8 The function of neuraminic acid is not known, but it has been implicated in the binding of biogenic amines,9,10 and in brain its concentration appears to fall after treatment with reserpine and chlorpromazine.44 Blood levels of neuraminic acid are altered in many diseases.11 In the cerebrospinal fluid (CSF), changes have been noted in parkinsonism12 and in schizophrenia.
Bogoch13 first reported that CSF of schizophrenic patients contains abnormally low levels of neuraminic acid. This conclusion was based on values obtained by measuring the chromophore