A new American study suggests that older people who have vision problems also have a greater risk for developing dementia.
Researchers looked at data from both the recent National Health and Aging Trends Study and the National Health and Nutrition Examination Survey (NHANES). Both of these studies compiled well over 32,000 medical records from Americans over the age of 60.
Every single person examined in these surveys had to tell doctors if they experienced any visual problems in recent years. Doctors also wrote down whether or not the patient had any mental disorders and/or memory problems. Only the NHANES survey objectively measured patients' eye health.
When scientists put the data of these two studies together, they found that around one-quarter of respondents had a dementia-like symptoms.
9 percent of participants in the NHANES test had poor distance vision scores. About 14 percent of respondents had near vision problems. Interestingly, about 30 percent of the participants in the NHANES survey said they experienced visual problems on a daily basis.
In the National Health and Aging study, 7 percent of respondents said they had distance vision problems. Only 5 percent admitted to having near vision issues in this survey.
As they looked for correlations in the data, researchers found that people who had low distance vision scores (below 20/40) were most susceptible to mental problems like Alzheimer's. They also found that people who thought they had distance vision problems were also at a higher risk for developing dementia. There wasn't as great a correlation between near vision patients and dementia.
Suzann Pershing, the chief of ophthalmology at the VA Palo Alto Health Care System, was one of the lead authors on this study. She told reporters that the link between eye issues and cognitive disease "makes intuitive sense." She went on to explain that, "vision impairment might lead to social disengagement and speed up cognitive decline."
Doctors have known for years that there's a direct correlation between hearing and memory decline. This is the first study to link visual impairment with dementia. While the medical community is aware of the correlation between neurosensory issues and cognitive functions, more research needs to be done.
Jennifer Evans, a teacher at the London School of Hygiene and Topical Medicine, used this study as a reminder for all people to get regular eye exams. Evans, who wrote the commentary to this report, told journalists, "Be aware of the potential for vision loss in yourself or in a family member with dementia."
Anyone interested in this research should check out the most recent edition of JAMA Ophthalmology. The two other researchers on this project include Stephanie P. Chen and Jay Bhattacharya. You'll find this study under the title, "Association of Vision Loss With Cognition in Older Adults."