The level of a neural cell adhesion molecule (NCAM) serum fragment in
autism was determined by using an antiserum prepared with immunoaffinity
purified mouse NCAM. Autistic patients (N = 16) had statistically
significantly decreased serum NCAM levels compared with age-matched
controls (p less than 0.0005). This observation could not be attributed to
a medication-induced effect. Depressed serum NCAM levels in autism are
distinct from schizophrenia, in which serum NCAM levels are elevated.