Mild Cognitive Impairment, Dementia Biomarker May Exist in Retinal Microvasculature

A biomarker for mild cognitive impairment (MCI) and dementia may be found within the retinal microvasculature, according to findings published in Eye. Measurements at the retinal capillary plexus (RCP) and ganglion cell complex (GCC) may be used to predict the severity of cognitive impairments, study authors report.

The researchers performed optical coherence tomography angiography (OCT-A) to obtain RCP vessel density and GCC thickness with detailed segments. To assess cognitive status, neuropsychologists used the Mini Mental State Examination and the Montreal Cognitive Assessment, and participants were then divided into 3 groups: normal cognition, mild cognitive impairment, and dementia. Multivariable analysis was used to measure relationship of ocular parameters with cognitive impairment.

The study took into account 2678 participants of the Jidong Eye Cohort Study (mean age, 44.1 years). MCI was present in 7.4% (n=197) of participants, and dementia was present in 3% (n=80) of participants. The adjusted odds ratio (OR) was 0.76 (95% CI 0.65–0.90) for the correlation of lower deep RCP with MCI, compared to the normal group.

A superficial (OR, 0.68 [0.54–0.86]) and deep (OR, 0.75 [0.57–0.99]) RCP, as well as the GCC (OR, 0.68 [0.54–0.85]) were associated with dementia. Participants with dementia had thinner GCCs (OR, 0.75 [0.58–0.97]), compared with the MCI group.

Altogether, the investigation shows that decreased deep RCP density can precede mild cognitive impairment, and decreased superficial and deep RCPs with thin GCCs
are associated with dementia.

“The association between SCP and MCI was only observed in participants aged <60 years. In addition, alcohol consumption strengthened the association between DCP and MCI, indicating that RCP loss was more serious in patients with MCI who consumed alcohol than those who did not,” the researchers report. “Therefore, we should pay special attention to RCP loss in young individuals who consume alcohol due to its interactive effects on the association with MCI. Lastly, we also found that participants with higher education levels had a stronger association between DCP and MCI than those with lower education levels.”

The study authors note that the identification of the associations between the retinal microvasculature and MCI and dementia may be useful for ophthalmologists in identifying cognitive impairment in patients.

Limitations of this research include the lack of generalizability of results to populations outside of northern China; the small number of participants in the dementia group; and the lack of assessment of progressive temporal changes in retinal vasculature and neural layer thicknesses.