Increased serum neopterin levels in adults with Down syndrome

We quantitated serum neopterin levels in Down syndrome (DS), normal controls, Alzheimer's disease, multiple sclerosis and other neurological diseases. We then analyzed the relationships with age, sex, apolipoprotein E (Apo E) phenotype, and amyloid beta protein 1-40 (Aβ40) and 1-42 (Aβ42) levels. Neopterin levels were higher in DS than all other groups. Levels in young DS (<40 years of age) and old DS (>41 years) were similar. There was no significant correlation between neopterin levels and age, sex, Apo E phenotype, and Aβ40 or Aβ42 levels in DS. This lack of correlation between neopterin and Aβ levels suggests that the higher neopterin concentrations in DS group reflect inflammatory cell activation rather than AD neuropathology.