Retinal neural, vascular structure linked to cognitive function in T1D

Noninvasive retinal imaging with optical coherence tomography (OCT) and OCT angiography (OCTA) helps in the assessment of risks for cognitive dysfunction in individuals with type 1 diabetes (T1D), a study has shown.

This observational cross-sectional study was conducted involving individuals with ≥50 years of T1D (Joslin Medalist Study) at a university hospital in the US to determine whether structural and vascular abnormalities of the retina, representing an extension of the central nervous system, were associated with cognitive impairment and other T1D complications.

A total of 129 patients with complete cognitive testing were enrolled. Validated cognitive testing measures included psychomotor speed and immediate and delayed memory.

The authors performed OCT and OCTA to obtain neural retinal layer thicknesses and vascular density for superficial (SCP) and deep retinal capillary plexus (DCP). Multivariable modeling was adjusted for potential confounders associated with outcomes in unadjusted analyses.

Reduced vessel density of the SCP and DCP resulted in worse delayed memory (DCP: p=0.002) and dominant hand psychomotor speed (SCP: p=0.01). Thinning of the retinal outer nuclear layer correlated with worse psychomotor speed both in dominant (p=0.05) and nondominant hands (p=0.01). Moreover, an association was found between outer plexiform layer thickness and delayed memory (p=0.04).

“Cognitive dysfunction is a growing and understudied public health issue in the ageing T1D population and is difficult and time-consuming to diagnose,” the authors said. “Studies in long-duration T1D have reported [that] the presence of proliferative diabetic retinopathy was associated with cognitive dysfunction.”