Besides, pathways (KEGG and Reactome) enrichment analysis revealed that dysregulated circRNAs were involved (via the intermediate roles of microRNAs and corresponding target proteins) in AD-related pathways (e.g., neurotrophin signaling pathway, dopaminergic synapse, apoptosis, mTOR, AMPK, and MAPK signaling pathway). Here, BDNF is linked to Alzheimer disease.