According to a new study by the University of South Australia, millions of older people with poor eyesight are at risk of being misdiagnosed with mild cognitive impairment.
Cognitive tests based on vision-dependent tasks can skew the results of up to a quarter of people over the age of 50 who have undiagnosed vision problems such as cataracts or age-related macular degeneration (AMD).
Age-related macular degeneration is a major cause of vision loss in the elderly. It does not lead to complete loss of vision, but seriously affects people’s ability to read, drive, cook, and even recognize faces. It has nothing to do with cognition.
UniSA researchers recruited 24 participants with normal vision to perform two cognitive tests – one with reactive tasks that depend on vision, and the other – based on fluent language.
Using a set of points to simulate AMD, participants scored significantly lower in a cognitive test that included response time tasks than without points. There was no statistical difference with word fluency tests when using points.
The study was published in Scientific reports.
UniSA PhD candidate Anne McNamara, who led the study, says the results are a vivid reminder that visual impairments – affecting approximately 200 million people worldwide over the age of 50 – unfairly affect cognitive scores when tests involve visual ability.
“An erroneous score in cognitive tests can have devastating consequences, leading to unnecessary changes in life, work, financial or social circumstances,” says McNamara.
“For example, if an erroneous assessment has contributed to the diagnosis of a mild cognitive impairment, it can cause psychological problems, including depression and anxiety.
“People with AMD are already experiencing a lot of vision loss problems, and inaccurate cognitive assessment is an extra burden they don’t need.”
UniSA scientists say that visual impairments are often ignored in scientific and clinical settings, with vision impairment underestimated by up to 50 percent of the elderly.
And given that this figure is expected to increase as the population ages, it is important that neurodegenerative disease researchers monitor vision when assessing people’s cognition.
“Mobile applications can now be used to impose simulated visual impairments on test materials when piloting their stimuli,” McNamara says.
“In addition, researchers can include quick and easy screening tasks before getting people to do cognitive tests. Oral assignments should also be part of the assessment.”
Source of history: