Poor eyesight is often confused with cognitive impairment.
According to a recent study from the University of South Australia (UniSA), millions of visually impaired adults are at risk of being misdiagnosed with mild cognitive impairment. Cognitive tests based on vision-dependent activities may have distorted results in up to a quarter of people over the age of 50 who have undiagnosed visual impairments, such as cataracts or age-related macular degeneration (AMD).
Age-related macular degeneration (AMD) is an eye disease that can dim your central vision and is a major cause of vision loss in older adults. It happens when aging causes damage to the macula - the part of the eye that controls clear, direct vision. The macula is part of the retina (the light-sensitive tissue in the back of the eye). AMD does not cause complete blindness, but loss of central vision can make it difficult to see faces, read, drive, or do close-up work, such as cooking or repairing things around the house.
Age-related macular degeneration is the most common cause of vision loss in the elderly. It does not result in total vision loss, but it does have a significant effect on people’s ability to read, drive, cook, and even identify faces. It has nothing to do with the intellect. Researchers at the University of South Australia selected 24 people with normal vision to take part in two cognitive tests, one involving reactive vision-dependent tasks and the other based on verbal fluency. Subjects performed much poorer on the cognitive test involving reaction time tasks when wearing goggles to simulate AMD. When wearing goggles, there was no statistically significant difference in verbal fluency assessments.
The research was recently published in the journal Scientific reports.
UniSA Ph.D. Candidate Anne Macnamara, who led the study, says the results are a clear reminder that visual impairment - which affects about 200 million people worldwide over the age of 50 - unfairly affects cognitive scores when tests involves visual skills.
“A wrong score on cognitive tests could have devastating consequences, leading to unnecessary changes in a person’s living, working, financial or social conditions,” says Macnamara. “For example, if a wrong score contributed to a diagnosis of mild cognitive impairment, it could trigger psychological problems, including depression and anxiety. People with AMD are already experiencing a number of problems due to vision loss, and an inaccurate cognitive assessment is an additional burden that they do not need. ”
Visual impairment is often overlooked in research and clinical settings, say UniSA researchers, the underestimated reduced vision in up to 50% of older adults. And given that this number is expected to grow as the population ages, it is essential that neuro-degenerative researchers monitor their vision when assessing people’s cognition.
“Mobile applications can now be used to overlay simulated visual impairments on test materials when piloting stimuli,” says Macnamara. “Researchers can also incorporate quick and easy screening tasks before getting people to take cognitive tests. Verbal tasks should always be part of the assessment. “
Reference: “The Effect of Age-Related Macular Degeneration on Cognitive Test Performance” by Anne Macnamara, Victor R. Schinazi, Celia Chen, Scott Coussens, and Tobias Loetscher, March 8, 2022, Scientific reports.
DOI: 10.1038 / s41598-022-07924-8