The Association Between Acquired Color Deficiency and PET Imaging of Neurodegeneration in Mild Cognitive Impairment and Alzheimer Disease

Abstract

Purpose To evaluate color vision changes and retinal processing of chromatic and luminance pathways in subjects with Alzheimer disease (AD) and mild cognitive impairment (MCI) compared with a matched control group and whether such changes are associated with impaired brain glucose metabolism and β-amyloid deposition in the brain. Methods We evaluated 13 patients with AD (72.4 ± 7.7 years), 23 patients with MCI (72.5 ± 5.5 years), and 18 controls of comparable age ( P = 0.44) using Cambridge color test and the heterochromatic flicker ERG (HF-ERG). The Cambridge color test was performed using the trivector protocol to estimate the protan, deutan and tritan color confusion axes. HF-ERG responses were measured at a frequency of 12 Hz, which ERGs reflect chromatic activity, and at 36 Hz, reflecting luminance pathway. A study subsample was performed using neuropsychological assessments and positron emission tomography. Results Patients with AD presented higher mean values indicating poorer color discrimination for protan ( P = 0.04) and deutan ( P = 0.001) axes compared with the controls. Along the tritan axis, both patients with AD and patients with MCI showed decreased color vision ( P = 0.001 and P = 0.001) compared with controls. The analyses from the HF-ERG protocol revealed no differences between the groups ( P = 0.31 and P = 0.41). Diffuse color vision loss was found in individuals with signs of neurodegeneration (protan P = 0.002, deutan P = 0.003 and tritan P = 0.01), but not in individuals with signs of β-amyloid deposition only (protan P = 0.39, deutan P = 0.48, tritan P = 0.63), regardless of their clinical classification. Conclusions Here, patients with AD and patients with MCI present acquired color vision deficiency that may be linked with impaired brain metabolism.

Alzheimer’s disease: a continuum with visual involvements

“…With respect to the deutan axis, we found statistically significant differences when we compared between the control group and both mild and moderate AD and when we compared between the FH+ and moderate AD groups. Similar than Vidal et al (2022), we also found no significant differences in the number of errors between the control and MCI groups.…”

“…Also, the moderate AD group showed a significant increase in the total number errors related to control group. This diffuse involvement has been observed by different authors (Pache et al, 2003;Salamone et al, 2009;Polo et al, 2017;Salobrar-García et al, 2019) and recently Vidal et al had found that individuals with AD and those with MCI display an acquired color vision deficiency, both in protan and tritan axism that is likely associated with compromised brain metabolism (Vidal et al, 2022).…”

“…In contrast, a loss in the tritan axis has been reported between the MCI subjects and the control group (Vidal et al, 2022). The MCI group is an intermediate stage between normal subjects and AD patients (Lewis et al, 1987;Black, 1996) that have worse MMSE scores (Vidal et al, 2022). In the present work, in all participants, we observed a negative correlation between the MMSE score and the total error number, tritan and deutan axis.…”

“…However, we found no significant differences in this axis between the MCI group and the control group. In contrast, a loss in the tritan axis has been reported between the MCI subjects and the control group (Vidal et al, 2022). The MCI group is an intermediate stage between normal subjects and AD patients (Lewis et al, 1987;Black, 1996) that have worse MMSE scores (Vidal et al, 2022).…”

The prevalence of red-green color vision deficiency and its related factors in an elderly population above 60 years of age

“…Various factors play a role in the development of acquired CVD, which cause problems in the reception and transmission of color signals to the brain by disrupting the visual system [3] . Among these factors are ocular diseases including cataracts [4] , refractive errors [5] , agerelated macular degeneration (AMD) [6] , glaucoma [7] , and retinal diseases [8] , neurological factors [9] , metabolic factors [10] , chronic diseases such as diabetes mellitus [11] , viral diseases such as COVID-19 [12] , drugs and toxins [13] , occupational [14] , and aging [15] .…”