New study establishes clearer link between vision loss and cognitive declines

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Scientists have long known that visually impaired older people are twice as likely to have cognitive decline, the fifth leading cause of disability in older people. But the specific types of visual and mental acuity involved remain unclear.

A new to study in the journal JAMA Network Open highlights them.

The longitudinal study of 1,200 dementia-free adults aged 60 to 94 looked at three types of vision loss and a full range of cognitive tests. Lead author Bonnielin Swenor of the Johns Hopkins Wilmer Eye Institute in Baltimore says work improves over previous studies, which often only looked at a single measure of vision or grouped together different types of cognition.

“This study is really unique because it has robust measures of vision and a full cognitive battery. So that means we have a lot of cognitive data in many cognitive domains,” Swenor said.

“So we could really determine which areas were affected or affected by each type of visual impairment,” said Swenor.

Loss of depth perception and visual acuity – the type of eye diagram test – correlates with greater declines in language and memory.

Loss of contrast sensitivity – the ability to see white milk in a white cup – was also linked to declines in language and memory, as well as reductions in attention and perception of spatial relationships.

This suggests that altered contrast sensitivity, which occurs in various eye diseases, might correlate with greater cognitive decline than visual acuity, which is more commonly measured in studies.

Ophthalmologist Heather Whitson heads the Duke University Center for the Study of Aging and Human Development. She sees the grainy results as a half-full cup of milk.

“In a way, you might say, ‘Well, if I lose one, I’m more likely to lose the other as well.’ But the flip side is that if we protect one, we may be more likely to protect the other, ”Whitson said.

The underlying factors that link vision loss to cognitive declines remain the subject of research and debate. But most explanations fall into two camps: either the same physiological problems affect both vision and cognition, as can occur in some vascular or inflammatory disorders, or the loss of vision results in other conditions that affect cognition, such as depression, social isolation, or loss of stimulating activities such as reading or crossword puzzles.

Whatever the cause, experts hope such findings will inform efforts to reduce the risk of cognitive decline through early detection and management of vision loss.

“It’s not like every type of vision puts you at risk for every type of cognitive loss. And once again my mind as a clinician turns to what this new information is giving us that might suggest how we might intervene. – how we might protect long-term cognition through better visual health, ”said Whitson.


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