OCT angiography shows promise for diagnosing Alzheimer’s

Clinicians can use optical coherence tomography angiography (OCTA) to non-invasively diagnose patients with early cognitive impairment, an early indicator of Alzheimer’s disease (AD), reported authors of a single-center study published in PLOS One.

Alzheimer’s patients exhibit decreased retinal blood flow and vessel density, but scientists still do not know if the same can be said for patients with a form of early cognitive impairment or early Alzheimer’s associated with a higher risk of progressing to dementia. 

To determine if OCTA parameters in two specific areas of the eye, the macula and disc, could help diagnose patients with early Alzheimer’s, the researchers compared 16 patients with mild cognitive impairment/early Alzheimer’s to 16 cognitively normal controls.

Amani A. Fawzi, MD, of Northwestern University in Chicago, and colleagues analyzed OCTA images of the parafoveal superficial capillary plexus (SCP) and two layers in the peripapillary region of the eye. The researchers compared the vessel length density (VLD), adjusted flow index and structural nerve fiber layer thickness between the two patient groups. These parameters were also examined against cognitive performance on the Montreal Cognitive Assessment (MoCA).

Overall, Fawzi et al. noted a “significant positive correlation” between MoCA scores for all patients and both the parafoveal SCP, vascular density and peripapillary radial peripapillary capillary and VLD.

In other words, “our study shows that compared to matched cognitively normal controls, participants with early cognitive impairment demonstrated significantly decreased superficial parafoveal vessel density and blood flow," the authors wrote.

“Most importantly, we demonstrated the role of OCTA in detecting early capillary changes, which may represent potentially early, non-invasive biomarkers of AD.”

Future research, the team noted, should be conducted longitudinally and with a larger cohort of patients.

“The clinical impact of these studies would be tremendous, given the often unpredictable clinical course of pre-AD individuals and the invasive and costly nature of current biomarkers that prohibits their widespread implementation,” Fawzi and colleagues concluded.