APOE and Parkinson disease: In the Parkinson's Progression Markers Initiative (PPMI) study following 423 individuals with de novo PD cohort over 2 years, decreased lymphocyte count was associated with decline in global cognitive performance over 2 years, but only in APOE e4 allele carriers, while NLR was not specifically examined.13, 14 Whether NLR is a predictor of global cognitive impairment or amnestic changes more typical of AD pathology versus non‐amnestic changes over time is not known.