Recent studies have indicated that serotonin 6 receptor (5‐HT6R) may be a potential target for cognitive improvement in Alzheimer's disease (AD) (Hu et al., 2017; Khoury et al., 2018; Ramirez, 2013), schizophrenia, and other cognitive or memory deficits. This evidence concerns the gene HTR6 and early-onset autosomal dominant Alzheimer disease.