Adults with Down syndrome display altered entrainment of occipital cortical neurons

Down syndrome is commonly associated with a trisomy of chromosome 21 that often presents an accelerated aging profile and higher probability of developing Alzheimer's disease-like symptoms at a relatively early age. However, the physiological changes that may contribute to such symptoms remain poorly understood. To begin to address this knowledge gap, we used magnetoencephalographic neurophysiological imaging to assess the entrainment of occipital cortical neurons to a 15 Hz visual stimulus in a cohort of adults with DS without a dementia diagnosis (N = 26; Age = 27.65 ± 9.55 years) and a demographically matched cohort of neurotypical controls (N = 22; Age = 30.81 ± 8.02 years). Our results indicated that adults with Down syndrome exhibit substantially weaker entrainment of the occipital cortical neurons and elevated spontaneous activity during the prestimulation baseline period compared with the controls. These results suggest that there are alterations in the integrity of occipital neural populations that may be attributable to an imbalance in local GABAergic activity and/or disruption in cholinergic pathways. These changes may affect the strength of resting cortical rhythms, leading to the elevated spontaneous activity observed here, which has been linked to reductions in the dynamic range of neural populations and impairments in perceptual and cognitive processing. These novel results advance our understanding of the occipital cortical physiology seen in adults with Down syndrome and provide foundational knowledge for the development of biomarkers for the early detection of accelerated aging and cognitive decline in those with Down syndrome.