ADORA1 and Alzheimer disease: Studies have shown that fear memory is impaired in AD [196,197], and in AD, several factors implicated in fear memory are compromised, including astrocytic L-lactate production and its transportation via monocarboxylate transporters [198,199], adenosine levels [200], α7 subunit of nicotinic acetylcholine receptors [201], adenosine A1 receptors [202], muscarinic acetylcholine M1 receptors [203], and IP3R2 [204].