How Vision Loss Can Lead to Cognitive Decline
Summary
- Dr. Diane Zheng’s research demonstrates the link between sight and cognition.
- Dr. Zheng found impairment of vision can lead to social isolation and depression and fuel cognitive impairment.
- Dr. Zheng and her team plan to explore how loss of vision, hearing and smell can impact cognition.
Diane Zheng, Ph.D., a research assistant professor of psychiatry and behavioral sciences at the University of Miami Miller School of Medicine, spent years researching the connection between vision and overall health and quality of life. But when she decided to study the specific connection between sight and cognition, she found that the two were very closely related, a finding that seemed to surprise the field.
“The paper got a lot of attention,” she said, when it was published in 2018.
Since then, Dr. Zheng and her team have published several more studies clarifying the relationship and providing evidence of the importance of maintaining visual health throughout life.
Vision Loss and Cognitive Decline
In the 2018 study, she and her team examined visual acuity and cognitive function for 2,520 individuals between the ages of 65 and 84. Subjects were tested up to four times over the course of eight years. The results showed that visual and cognitive decline seemed to go hand in hand. The rate of vision loss is related to the rate of cognitive decline and further analysis suggested that vision loss has a stronger effect on cognition than the other way around.
Visual decline is very common as people get older. But so many people, including ophthalmologists, are still not aware of the important link between vision and cognition.
How Vision Affects Cognition
After the 2018 study, Dr. Zheng and her team started to dig deeper into the relationship between vision and cognition.
“We know there are different ways vision can affect cognitive decline,” she said.
In a 2024 study of Hispanic participants who were not part of the previous studies, Dr. Zheng and her team found that impaired hearing and vision as measured by objective tests were both linked with cognitive decline. Interestingly, while self-reported vision loss was connected to reduced cognitive function, self-reported hearing loss was not. This may be because hearing loss happens slowly over time and many aging adults don’t realize their hearing loss.
Dr. Zheng hopes to better understand how sensory issues lead to cognitive decline in Hispanic and African American populations through future research.
Dr. Zheng’s most recent study started to tease apart these different mechanisms in participants across a range of ages and genders. For example, vision loss can make it harder to participate in certain activities and socialize. That can cause people to become isolated, which leads to a lack of brain stimulation and subsequent cognitive decline, a sequence of events more common among older men in the study. On the other hand, vision loss contributes to cognitive decline by exacerbating depressive symptoms, a pathway more common in middle-aged women.
“When I saw that result, I thought, ‘Wow, this is striking and physicians need to know this,’” said Dr. Zheng.
Expanding the Sense Exploration
Vision isn’t the only sense linked with cognition. In upcoming studies, Dr. Zheng and her team plan to explore how loss of vision, hearing and smell can impact cognition. She expects that each sensory difficulty, individually, will increase the risk of dementia, but if a person is losing more than one sense simultaneously, the risk of cognitive decline could be even higher.
The most important takeaway from her work, she said, is “as you or your family members get older, I urge you to take care of your senses and have yearly vision and hearing examinations. These senses have an impact not only on your quality of life but also in maintaining your cognition.”
Tags: cognition, cognitive decline, dementia, Department of Psychiatry and Behavioral Sciences, Diane Zheng, Psychiatry and Behavioral Sciences, vision impairment, vision loss