Decrease in visual chromatic sensitivity as a potential biomarker for early detection of mild cognitive impairment: a pilot study

Abstract

Background: Vision is essential to maintain daily activities and quality of life. Older adults with cognitive impairment face visual challenges. In particular, colour vision requires an intact visual pathway, starting from the retina to the brain, and a good brain function for colour information processing. In this pilot study, we conducted comprehensive eye examinations for older adults with different cognitive capabilities to determine the feasibility of using chromatic sensitivity as a biomarker for early detection of mild cognitive impairment (MCI). Methods: In total, 44 women and 12 men aged 60 to 91 (mean, 73.5±8.2) years were recruited and completed all eye examinations that included visual acuity, external and internal ocular health, contrast sensitivity, and colour vision. Cognitive function was assessed using the Cantonese version of the Mini-Mental State Examination (MMSE). Results: Of the participants, 42.9% had MCI (based on MMSE cutoff score of 24 or 25), with a mean score of 24.52±4.73 out of 30. The visual acuity and contrast sensitivity were significantly better in normal participants than participants with MCI (p<0.05). Interestingly, participants with MCI were subjectively more aware of a reduced vision (p<0.05) and had a higher rate (despite not significantly) of having problems on ocular health issues such as cataract and macular degeneration. The MMSE score was positively correlated with colour vision, even after controlling for covariates. This indicates that colour vision is an independent factor in relation to cognitive function. Conclusion: MCI is difficult to detect when the symptoms are mild. Patients with MCI are more aware of a reduced vision, which may be indicative of an impaired cognitive ability. Decline in colour vision may be a sign for the early detection of MCI. Regular eye examination is recommended for early detection of visual and cognitive impairments.

Background: Vision is essential to maintain daily activities and quality of life. Older adults with cognitive impairment face visual challenges. In particular, colour vision requires an intact visual pathway, starting from the retina to the brain, and a good brain function for colour information processing. In this pilot study, we conducted comprehensive eye examinations for older adults with different cognitive capabilities to determine the feasibility of using chromatic sensitivity as a biomarker for early detection of mild cognitive impairment (MCI). Methods: In total, 44 women and 12 men aged 60 to 91 (mean, 73.5±8.2) years were recruited and completed all eye examinations that included visual acuity, external and internal ocular health, contrast sensitivity, and colour vision. Cognitive function was assessed using the Cantonese version of the Mini-Mental State Examination (MMSE). Results: Of the participants, 42.9% had MCI (based on MMSE cutoff score of 24 or 25), with a mean score of 24.52±4.73 out of 30. The visual acuity and contrast sensitivity were significantly better in normal participants than participants with MCI (p<0.05). Interestingly, participants with MCI were subjectively more aware of a reduced vision (p<0.05) and had a higher rate (despite not significantly) of having problems on ocular health issues such as cataract and macular degeneration. The MMSE score was positively correlated with colour vision, even after controlling for covariates. This indicates that colour vision is an independent factor in relation to cognitive function. Conclusion: MCI is difficult to detect when the symptoms are mild. Patients with MCI are more aware of a reduced vision, which may be indicative of an impaired cognitive ability. Decline in colour vision may be a sign for the early detection of MCI. Regular eye examination is recommended for early detection of visual and cognitive impairments.