As observed in AD, the magnitude of the reduction in PNN glycans appears to be much greater than the associated aggrecan core protein (Pantazopoulos et al., 2015; Enwright et al., 2016), which agrees with recent findings for decreased expression of CS-GAG biosynthesis genes but increased CSPG core protein expression in postmortem SZ human brain tissue (Pantazopoulos et al., 2021). Here, ACAN is linked to Alzheimer disease.