Synaptotamin-1 concentrations were increased in patients with MCI due to Alzheimer’s disease and patients with dementia due to Alzheimer’s disease compared with controls, supporting the notion that synaptotagmin-1 could be a valuable differential biomarker both in early Alzheimer’s disease and after manifestation of the disease. This evidence concerns the gene SYT1 and early-onset autosomal dominant Alzheimer disease.