The retina shows promise for early detection of Alzheimer's disease and related dementias as it is the only part of the central nervous system that can be observed directly. Moreover, technology to capture images of the retina is cost-effective, non-invasive, and already widely available in eye clinics and retail optometrists.
In the current study, researchers set out to understand whether midlife retinal neuronal and microvascular measures are linked to risk for Alzheimer's disease and related dementia. To do so, they analyzed data from the Dunedin study, which includes a New Zealand-based cohort of 1037 participants representing the country's full range of socioeconomic status. Ethnicity-wise, the cohort was mostly New Zealand European/Pākehā. Data analyzed included measures of retinal health and established risk indexes for Alzheimer's disease and related dementia at 45 years of age.
Ultimately, narrower arteries, wider venules, and thinner retinal nerve fiber layers were linked with a higher risk of dementia. Further tests indicated that while thinner retinal nerve fiber layers reflected cardiometabolic risk, microvascular measures were linked to diverse risk factors.
"I was surprised that venules were associated with so many different domains of Alzheimer's disease -- that suggests that it might be a particularly useful target for assessing dementia risk," said co-lead author, Dr. Ashleigh Barrett-Young of the Department of Psychology at the University of Otago, New Zealand, in a press release.
There are limitations to the findings. As the study was observational, it can't establish causation. The results should additionally be replicated in more diverse samples as evidence shows that retinal parameters may differ among different racial and ethnic groups.
"This research is still in an early stage, and we can't predict your future looking at an eye scan. Hopefully, one day we'll be able to use AI methods on eye scans to give you an indication of your brain health, but we're not there yet," added Barrett-Young.
Sources: Science Daily, Journal of Alzheimer's Disease
