Down syndrome (DS) was the most prevalent inherited reason of intellectual disability worldwide. Using electrophysiological measures to evaluate DS children may provide mechanistic insights into ID, allowing biomarkers and intervention targets to be identified. Due to methodological variations between research and insufficient controls for cognitive deterioration as a potential cofounder, electrophysiological characteristics relating to DS remain enigmatic. In occipital and frontal parts as compared between adults with DS and typically developing (TD) matched (n=25 per group) controls and particularly delta, theta, alpha, and beta absolute and relative powers, and alpha peak amplitude, frequency, and frequency variance) were evaluated by eyes-closed resting-state EEG. The researchers observed an overall ‘slower’ EEG spectrum in people with DS, characterized by higher delta and theta power, lower alpha and beta power. PatientsIndividuals with DS had lower alpha activity than the control group, which was associated with a decreased power, greater peak amplitude, and more frequency variance. In the past, researchers have linked slowing of the electrical activity in the brain to cognitive decline in both DS and TD people. The results suggested that a common EEG signature of cognitive impairment, regardless of source (neurodevelopmental or neurodegenerative), may exist, demanding further research.