Abstract
Building on previous studies that report thinning of the macula in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) patients, the use of optical coherence tomography (OCT) has been proposed as a potential biomarker for AD. However, other studies contradict these results. A total of 930 participants (414 cognitively healthy people, 192 with probable amnestic MCI, and 324 probable AD patients) from a memory clinic were consecutively included in this study and underwent a spectral domain OCT scan (Maestro, Topcon) to assess total macular volume and thickness. Macular width measurements were also taken in several subregions (central, inner, and outer rings) and in layers such as the retinal nerve fiber (RNFL) and ganglion cell (CGL). The study employed a design of high ecological validity, with adjustment by age, education, sex, and OCT image quality. AD, MCI, and control groups did not significantly vary with regard to volume and retinal thickness in different layers. When these groups were compared, multivariate-adjusted analysis disclosed no significant differences in total (p = 0.564), CGL (p = 0.267), RNFL (p = 0.574), and macular thickness and volume (p = 0.380). The only macular regions showing significant differences were the superior (p = 0.040) and nasal (p = 0.040) sectors of the inner macular ring. However, adjustment for multiple comparisons nullified this significance. These results are not supporting existing claims for the usefulness of macular thickness as a biomarker of cognitive impairment in a memory unit. OCT biomarkers for AD should be subject to further longitudinal testing.
Highlights
The diagnosis of Alzheimer’s disease (AD), the most frequent neurodegenerative disease, requires clinical diagnostic criteria which do not get to differentiate this disease accurately from other causes of dementia[1]
mild cognitive impairment (MCI) symptoms can be stable for many years or even disappear; it is clear that the amnestic and multidomain MCI raises the progression risk to AD5,6
The goal of this paper is to assess the clinical usefulness and viability of the analysis of all main macular parameters obtained through Optical coherence tomography (OCT) automatic segmentation in the differentiation of controls, MCI, and AD in the work routine of a memory unit (MU)
Summary
The diagnosis of Alzheimer’s disease (AD), the most frequent neurodegenerative disease, requires clinical diagnostic criteria which do not get to differentiate this disease accurately from other causes of dementia[1]. Before dementia phase is established, cognition problems develop in a slow but progressive way, and can interfere limitedly in daily activities. This prodromal stage, called mild cognitive impairment (MCI), is a clinically heterogeneous syndrome and a consequence of different etiologies. Even when a set of biomarkers have been approved and incorporated into the new clinical diagnostic criteria[8,9], most demonstrate suboptimal test precision and involve either prohibitive costs or substantially invasive processes[10,11]. Unmyelinated axons of neurons in the ganglion cell layer (CGL) build the retinal nerve fiber layer (RNFL). These fibers continue as the optic nerve into the brain. OCT is utilized regularly in clinical ophthalmology to assess retinal integrity and is a promising tool for neurological investigation because of its high correlation with a number of visual electrophysiological tests[13,14] and considerable reliability in a wide range of neurological pathologies[15,16]
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