Disruption of early visual processing in amyloid-positive healthy individuals and mild cognitive impairment

Abstract

Background Amyloid deposition is a primary predictor of Alzheimer’s disease (AD) and related neurodegenerative disorders. Retinal changes involving the structure and function of the ganglion cell layer are increasingly documented in both established and prodromal AD. Visual event-related potentials (vERP) are sensitive to dysfunction in the magno- and parvocellular visual systems, which originate within the retinal ganglion cell layer. The present study evaluates vERP as a function of amyloid deposition in aging, and in mild cognitive impairment (MCI). Methods vERP to stimulus-onset, motion-onset, and alpha-frequency steady-state (ssVEP) stimuli were obtained from 16 amyloid-positive and 41 amyloid-negative healthy elders and 15 MCI individuals and analyzed using time–frequency approaches. Social cognition was assessed in a subset of individuals using The Awareness of Social Inference Test (TASIT). Results Neurocognitively intact but amyloid-positive participants and MCI individuals showed significant deficits in stimulus-onset (theta) and motion-onset (delta) vERP generation relative to amyloid-negative participants (all p < .01). Across healthy elders, a composite index of these measures correlated highly (r = − .52, p < .001) with amyloid standardized uptake value ratios (SUVR) and TASIT performance. A composite index composed of vERP measures significant differentiated amyloid-positive and amyloid-negative groups with an overall classification accuracy of > 70%. Discussion vERP may assist in the early detection of amyloid deposition among older individuals without observable neurocognitive impairments and in linking previously documented retinal deficits in both prodromal AD and MCI to behavioral impairments in social cognition.

Exploring the Relationship between Behavioral and Neurological Impairments Due to Mild Cognitive Impairment: Correlation Study between Virtual Kiosk Test and EEG-SSVEP

“…To enhance understanding, we established three components for naming neurological features: (1) the PS frequency (3,5,10,12,15, and 20 Hz), (2) the target lobe (parietal lobe, POR), and (3) the specific frequency ranges used in different analysis methods, namely power and connectivity. For instance, in power analysis, '1H' refers to the fundamental harmonic, while '2H' represents the second harmonic in response to visual stimuli.…”

“…In response to the urgent need for early detection of aMCI, a large variety of diagnostic tools such as virtual reality (VR), magnetic resonance imaging (MRI), and electroencephalography (EEG) have been used in recent years. For example, VR shows promise in providing features for aMCI screening through the assessment of instrumental activities of daily living (IADLs), which evaluates cognitive function during complex activities in everyday life [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Employing head-mounted displays (HMDs) and hand controllers allows for the easy tracking and recording of behavioral features such as eye and hand movements.…”

Retina pathology as a target for biomarkers for Alzheimer's disease: Current status, ophthalmopathological background, challenges, and future directions

“…The retina is a promising target for developing minimally invasive, scalable, cost‐effective, and accessible AD risk screening or disease‐monitoring markers. Its shared embryologic origin and cellular composition with the brain, 16 , 17 , 18 its direct connection with several brain regions, its accessibility by point‐of‐care clinicians using standard ophthalmological techniques, and data showing that visual changes manifest in the earliest stages of AD 19 , 20 , 21 , 22 , 23 , 24 render the retina an ideal AD risk biomarker target. Several retinal imaging techniques have been developed to determine AD‐associated lesions.…”