GHRL and early-onset autosomal dominant Alzheimer disease: Ghrelin is also involved in mitochondrial respiration and neuroprotection, which can be developed as biomarkers or drug targets for prevention and treatment of neurological disorders, including Parkinson's disease, stroke, epilepsy and Alzheimer's disease (dos Santos et al., 2013a; Shi et al., 2014, 2017; Stoyanova, 2014).