Thinner retinal nerve fiber layer may be a biomarker for dementia, according to a study.
Alzheimer disease (AD), the most common subtype of dementia, is characterized by the accumulation of misfolded amyloid-ß and tau protein in the brain, already occurring in the preclinical stages. Amyloid-ß deposits are also present in the retina of patients with AD.
Based on this association, several OCT studies have investigated potential parallel findings in the anatomy of the brain and retina and found that patients with AD have a thinner retinal nerve fiber layer (RNFL) and ganglion cell–inner plexiform layer (GC-IPL) compared with controls. However, the temporal relation of retinal thinning and dementia remained unclear.
Within the large population of the Rotterdam Study, the present study aimed at investigating the association of inner retinal layer thickness with prevalent and incident dementia in a general population of Dutch adults and also at finding out whether retinal thinning precedes the occurrence of dementia or can only be seen after the diagnosis of the disease has been made.
A total of 3,289 individuals were included They were screened and continuously monitored for dementia between 2001 and 2012. They also underwent regular retinal imaging with fundus photography and OCT. Of these, 41 already had dementia at baseline, and 86 developed dementia during the study period.
Thinner RNFL at baseline was significantly associated with a higher risk of developing dementia.
“In line with findings from previous studies, we found that particularly thinner GC-IPL tended to be statistically significantly associated with prevalent dementia. More importantly, our study is the first that shows an association between thinner RNFL and the risk of dementia, including AD, to our knowledge,” the authors wrote.
They hypothesized that brain degeneration occurring in dementia may affect the neuronal connections of the visual tract and manifest in the retina initially as thinner RNFL and as thinning of the GC-IPL at a later stage.
For dementia prediction, there is currently no established prediction models available, they noted, “but future studies should consider taking retinal structures into account.”– by Michela Cimberle
Disclosures: None of the authors reported a relevant financial disclosure.