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Objective:To quantify the associations of peripapillary retinal nerve fiber layer (pRNFL) thickness and macular ganglion cell layer (mGCL) volume with cognitive functioning, as well as to investigate how demographic and vascular health factors impact upon these associations, in a population-based sample of adults.Methods:The sample included the first 3000 participants (age range = 30 – 95) of the Rhineland Study (recruited from March 2016 to December 2018), who underwent spectral-domain optical coherence tomography (SD-OCT) and cognitive assessment at one of two identical study centres in Bonn, Germany. We used multiple linear regression models to examine the relationships between retinal layer measurements and cognitive functioning after adjustment for confounders, and also examined the moderating effects of demographic and vascular health factors.Results:The analytical sample included 2,483 participants, who were 54.3 years old (standard deviation = 13.8 years), on average. After full adjustment, each standard deviation decrease in mGCL volume was associated with a greater decrease in global function than that of pRNFL thickness (β = -0.048 [95% confidence interval (CI) = -0.077, -0.018] vs. β = -0.021 [95% CI = -0.049, 0.007]). These relationships increased in strength with advancing age, were stronger in participants with hypertension, and were reversed in current smokers relative to non-smokers.Conclusions:Macular GCL volume is more strongly related to adult cognitive functioning than pRNFL thickness, making it a better potential biomarker of neurodegeneration. Age and vascular health factors play important roles in determining the strength and direction of this association.

Abstract Background Age-related hearing loss (impairment in hearing sensitivity and/or higher-order auditory processing) and cognitive decline are common co-occurring impairments in elderly adults. Their relation in the process of aging remains insufficiently understood. We aim to assess the temporal relations of decline in hearing sensitivity, higher-order auditory processing, and cognition in middle-aged adults. Methods This study included 1,274 Beaver Dam Offspring Study participants who participated in three examinations (baseline, 5-year, and 10-year follow-up). We assessed hearing sensitivity through pure-tone audiometry (PTA, averaged thresholds of 0.5, 1, 2, 4 kHz of the better ear), higher-order auditory processing as word recognition in competing message (WRCM) using the Northwestern University 6 word list in the better ear, and cognition through trail-making test performance (TMT). Linear mixed-effects models and linear regression models were used to determine associations over time and to what extent these measures influence each other over time. Results The longitudinal decline between all functions was associated with the strongest relationships between PTA and WRCM. The effect of baseline PTA on WRCM 10 years later (standardized ß = –.30) was almost twice as big as the effect of baseline WRCM on PTA 10 years later (standardized ß = –.18). The effect of baseline WRCM on TMT 10 years later and vice versa were small (standardized ß = –.05). No directional relationship between PTA and TMT was identified (standardized ß ≤ .02). Conclusions While hearing sensitivity might affect higher-order auditory processing, associations between hearing and cognition appear bidirectional and weak in midlife. We need to be cautious before inferring causal effects of hearing on cognition.

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Background Neurodegenerative diseases are public health challenges in aging populations. Early identification of people at risk for neurodegeneration might improve targeted treatment. Noninvasive, inexpensive screening tools are lacking but are of great potential. Optical coherence tomography (OCT) measures the thickness of nerve cell layers in the retina, which is an anatomical extension of the brain and might be indicative of common underlying neurodegeneration. We aimed to determine the association of macular ganglion cell-inner plexiform layer (mGCIPL) thickness with cognitive and sensorineural function in midlife. Method This cross-sectional study included 1,880 Beaver Dam Offspring Study participants (aged 27–93 years, mean 58) who participated in the 10-year follow-up examination. We assessed cognitive function and impairment, hearing sensitivity thresholds and impairment, central auditory processing, visual impairment, and olfactory impairment. We measured mGCIPL using the Cirrus 5000 HD-OCT Macular Cube Scan. Multivariable linear and logistic regression models adjusted for potential confounders were used to determine associations between mGCIPL thickness and cognitive and sensorineural functions, as well as for comparing participants with a thin mGCIPL (1 SD below average) to the remainder in those functions. Results Thinner mGCIPL was associated with worse cognitive function, worse central auditory function, and visual impairment. We found an association of mGCIPL thickness with hearing sensitivity in women only and no association with impairment in hearing, olfaction, and cognition. Results on the thin group comparisons were consistent. Conclusions mGCIPL thickness is associated with cognitive and sensorineural function and has the potential as a marker for neurodegeneration in middle-aged adults.

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