A new US study suggests that screening for retinopathy, a disease of blood vessels in the retina at the back of the eye, could serve as a marker for brain health, after researchers found that women aged 65 and over with even a mild form of the disease were more likely to have cognitive decline and related vascular changes in the brain.
For the study, lead author Dr Mary Haan, professor of epidemiology and biostatistics at the University of California, San Francisco (UCSF), and colleagues, used data from the Women’s Health Initiative Memory Study and the Site Examination study, two sub-investigations of the Women’s Health Initiative Clinical Trial of Hormone Therapy.
The findings, which they report in the 14 March online issue of Neurology, suggest that a simple eye test could look for early signs of retinopathy, and serve as a marker for cognitive changes linked to vascular disease. This would allow for earlier diagnosis and treatments that potentially reduce the progression of cognitive impairment to dementia.
Retinopathy usually results from Type II diabetes or high blood pressure (hypertension). So an early diagnosis of this eye disease could indicate early stages of these two conditions, allowing for timely changes in lifestyle or drug interventions, when they might have the most impact.
Haan told the press:
“Lots of people who are pre-diabetic or pre-hypertensive develop retinopathy.”
“Early intervention might reduce the progression to full onset diabetes or hypertension,” she added.
For their study, the researchers analyzed data on 511 women with an average age of 69 years at the start of a 10-year follow up during which the women underwent an annual cognition assessment that tested their short-term memory and thinking ability. One test, for example, asked them to listen to several words, and then recall them after five minutes.
They also had had an eye test in the fourth year of follow-up, and a brain scan in the eighth year.
The results showed that during the follow-up, 39 (7.6%) of the participants developed retinopathy, and on average, their scores on the cognition tests were worse than the women who did not develop the eye disease.
When they examined the brain scans, the researchers saw that the women with retinopathy had more damage in their brain blood vessels. Specifically, they had 47% more ischemic lesions or holes in the overall blood vessel structure, and 68% in the parietal lobe.
Such lesions are thought to be caused by high blood pressure. They are typically seen with vascular disease and sometimes stroke.
Another feature that was more prominent in the brain scans of the women with retinopathy was more thickening of the white matter tracks that transmit signals in the brain. These thickenings are also thought to be due to high blood pressure.
However, retinopathy was not linked to more brain atrophy, which is a hallmark of Alzheimer’s disease, suggesting that retinopathy is probably not a marker for Alzheimer’s disease, said Haan.
In an accompanying editorial, Dr Rebecca F. Gottesman, Assistant Professor, Neurology at Johns Hopkins Intracerebral Hemorrhage Center, writes:
“This study highlights the potential importance of retinal evaluation in understanding the extent of cerebral microvascular disease that may be present in older adults.”
She points out that:
“Retinopathy was significantly associated with cognitive scores and cerebral microvascular disease independent of the effect of hypertension and diabetes,” suggesting that either it “captures information beyond a simple binary yes/no diagnosis of hypertension and diabetes, or that perhaps preclinical disease is better captured with measures of retinopathy …”
“Further studies that evaluate the role of retinal screening in individuals at risk for cognitive impairment or dementia and the impact of this screening on subsequent cognitive decline are needed,” she urges.
Funds from the National Heart, Lung and Blood Institute, the US Department of Health and Human Services, Wyeth Pharmaceuticals, and the National Institute on Aging helped pay for the study.
Written by Catharine Paddock PhD