NR4A2 and Alzheimer disease: At present, the research hotspots in this field are still focused on “death,” “amyotrophic lateral sclerosis,” “Alzheimer’s disease,” “biomarker,” “pathophysiology,” “impairment,” “neurodegenerative disease,” “amyloid precursor protein,” “single nucleotide polymorphisms (SNP),” “long non-coding RNA,” “3′ untranslated region,” “Nr4a2,” “synaptic plasticity,” “circular RNA,” and “central nervous system.”