Cognitive ability in Down syndrome and its relationship to urinary neopterin, a marker of activated cellular immunity

Abstract

Background: Neopterin is an unconjugated pteridine that is secreted in large quantities by activated macrophages and can be used as a clinical marker of activated cellular immunity and oxidative stress. We aimed to investigate whether urinary neopterin levels are associated with cognitive function in people with Down syndrome (DS).

Methods: Out of 32 adults with DS who originally participated in a longitudinal study, 25 were followed up at 4 years. Informants rated their adaptive behavior (ABAS) and the adults with DS attempted assessments of language skills and memory at both baseline and follow-up time points (Modified Memory Object Task, MOMT), and receptive vocabulary (British Picture Vocabulary Scale, BPVS).

Results: Neopterin/creatinine levels were negatively correlated with change in the MOMT total score (Spearman's Rho=-0.517, p=0.020) and change in the MOMT delayed recall score (Spearman's Rho=-0.577, p=0.008) over time, i.e. higher neopterin/creatinine level was associated with worse performance on a test of cognitive ability over time.

Conclusion: Urine neopterin may have potential as a biomarker for memory decline in Down syndrome, and could potentially also help to track progression of mild cognitive impairment (MCI) to Alzheimer's disease in other high risk populations.

Keywords: Aging; Alzheimer’s disease; Down syndrome; Memory; Neopterin; Oxidative stress.