Abstract
Purpose :
Biomarkers are urgently needed for frontotemporal lobar degeneration patients with a tauopathy (FTLD-Tau), as clinical presentations can be similar to Alzheimer’s disease (AD) despite distinct neuropathology. Since AD has been associated with choroidal thinning compared to normal controls, we determined the choroid’s biomarker potential for these dementias.
Methods :
36 probable FTLD-Tau (pFTLD-Tau), 32 probable AD (pAD), and 54 normal control subjects were recruited consecutively. Patients had a validated cerebrospinal fluid biomarker (amyloid-beta42: amyloid-beta40 ratio ≤ 0.058 or phosphorylated-tau: amyloid-beta42 ratio > 0.08) to determine presence or absence of AD. Further, pFTLD-Tau patients all had a clinical syndrome highly-associated with FTLD-Tau, or there was genetic (2 patients with a pathogenic MAPT mutation) or autopsy data (N=3) confirming FTLD-Tau. Spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering, Carlsbad, CA) with choroid enhanced depth imaging was performed. The Scheie Image Reading Center performed masked manual measurements of choroidal thickness (CT) and used ImageJ to determine vessel lumen and total choroidal areas. Results for each eye were the mean of measurements by two independent graders with adjudication by the Reading Center Director (ED). Choroidal vascularity index (CVI) was defined as choroidal vessel lumen area divided by total choroidal area. Multivariable linear regression models were performed and the inter-eye correlation was accounted for by using generalized estimating equations.
Results :
Twenty-seven (46 eyes) pFTLD-Tau, 25 (47 eyes) pAD, and 53 (80 eyes) control subjects were analyzed with mean ages of 66.5, 61.8, and 58.1 years, respectively. The subfoveal CT was 301.7, 290.3, and 301.5 microns, respectively (all p>0.05 for each group comparison). Adjusting for age, sex, and race, the subfoveal CT mean difference (microns) and the CVI was not significantly different between these groups (all p>0.05, Table 1). Measurement of CT at 12 other locations within 1500 microns of the fovea also showed no significant difference between these groups (all p>0.05), except at 1500 microns superior to the fovea (326.2 vs. 287.3, p=0.04, pAD vs. controls).
Conclusions :
Our study found no significant biomarker potential of the CT or CVI between pFTLD-Tau, pADNC, and normal controls.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.