Ghrelin is a 28–amino acid peptide derived from the cleavage of a prepropeptide having 117 residues [292,293], which has a major influence on the modulation of appetite and food intake [294] but also has been linked to depression, stress, and anxiety [292,295], most probably due to its well-known orexigenic effects. This evidence concerns the gene GHRL and depressive symptom measurement.