Afferent and Efferent Visual Markers of Alzheimer’s Disease: A Review and Update in Early Stage Disease

Abstract

Vision, which requires extensive neural involvement, is often impaired in Alzheimer's disease (AD). Over the last few decades, accumulating evidence has shown that various visual functions and structures are compromised in Alzheimer's dementia and when measured can detect those with dementia from those with normal aging. These visual changes involve both the afferent and efferent parts of the visual system, which correspond to the sensory and eye movement aspects of vision, respectively. There are fewer, but a growing number of studies, that focus on the detection of predementia stages. Visual biomarkers that detect these stages are paramount in the development of successful disease-modifying therapies by identifying appropriate research participants and in identifying those who would receive future therapies. This review provides a summary and update on common afferent and efferent visual markers of AD with a focus on mild cognitive impairment (MCI) and preclinical disease detection. We further propose future directions in this area. Given the ease of performing visual tests, the accessibility of the eye, and advances in ocular technology, visual measures have the potential to be effective, practical, and non-invasive biomarkers of AD.

Analysis of pupillometer results according to motor symptom severity in patients with Parkinson’s disease

“…After matching, the age difference between the two groups decreased from 7 to 2 years, and the statistical differences in age between the two groups also disappeared. The late stage group had a longer disease duration (4 [2-7] years vs. 6 [4][5][6][7][8][9] years, P = 0.007) and a higher LEDD (387 ± 190 mg vs. 642 ± 296 mg, P < 0.001) than the early stage group. Constriction velocity (2.25 ± 0.64 mm/s vs. 1.89 ± 0.57 mm/s, P = 0.006) and maximum constriction velocity (3.31 ± 0.90 mm/s vs. 2.79 ± 0.80 mm/s, P = 0.005) were signi cantly lower in the late stage group than in the early stage group (Figure 2).…”

“…3,4 In previous studies, compared with healthy age-matched subjects, patients with AD or PD, had signi cantly lowered maximum constriction velocity and maximum constriction amplitude, among the other components of PLR. 5,6 In previous studies on patients with PD, pupillometry results were helpful in detecting subclinical autonomic dysfunction; however they did not show a correlation with disease duration, the motor section of the Uni ed Parkinson's disease rating scale (UPDRS), or with the presynaptic dopaminergic dysfunction. 6,7 In this study, we investigated whether there is a relationship between the severity of motor symptoms and pupillometry ndings in PD patients.…”

Automated High-Definition MRI Processing Routine Robustly Detects Longitudinal Morphometry Changes in Alzheimer’s Disease Patients

“…The brain region at the TPOJ has been discussed in the context of highest cognitive functions including integration of external and body information ( Abu-Akel and Shamay-Tsoory, 2011 ), making moral decisions ( Blanke and Arzy, 2005 ) and theory of mind ( Saxe and Kanwisher, 2003 ) and is well known to be affected by AD ( Coughlan et al, 2018 ). By contrast, the visual cortex is affected relatively late in the course of the disease ( Albers et al, 2015 but see also Wu et al, 2020 ). Therefore, our longitudinal results are in line with current knowledge about brain atrophy in AD.…”

The search for a convenient procedure to detect one of the earliest signs of Alzheimer's disease: A systematic review of the prediction of brain amyloid status

“…Some notable studies were not included in this review as they did not meet inclusion criteria or were published beyond our search date. Non‐invasive imaging detected differences in retinal Aβ between MCI/AD participants and age‐matched controls, 120 part of a promising field investigating the use of eye biomarkers in this context of interest 121,122 . Very recently, several groups have reported development of assays for plasma ptau181 20,123 and ptau217, 22–25 the second biomarker in the A/T/N framework 1 .…”