The Bidirectional Relationship between Vision and Cognition

Abstract

Topic: Visual impairment (VI) and cognitive impairment (CIM) are prevalent age-related conditions that impose substantial burden on the society. Findings on the hypothesized bidirectional association of VI and CIM remains equivocal. Hence, we conducted a systematic review and meta-analysis to examine this bidirectional relationship.Clinical Relevance: Sixty percent risk of CIM has not been well elucidated in the literature. A bidirectional relationship between VI and CIM may support the development of strategies for early detection and management of risk factors for both conditions in older people.Methods: PubMed, Embase, and Cochrane Central registers were searched systematically for observational studies, published from inception until April 6, 2020, in adults 40 years of age or older reporting objectively measured VI and CIM assessment using clinically validated cognitive screening tests or diagnostic evaluation. Meta-analyses on cross-sectional and longitudinal associations between VI and CIM outcomes (any CIM assessed using screening tests and clinically diagnosed dementia) were examined. Random effect models were used to generate pooled odds ratios (ORs) and 95% confidence intervals (CIs). We also examined study quality, publication bias, and heterogeneity.Results: Forty studies were included (n ¼ 47 913 570). Meta-analyses confirmed that persons with VI were more likely to have CIM, with significantly higher odds of: (1) any CIM (cross-sectional: OR, 2.38 [95% CI, 1.84e3.07]; longitudinal: OR, 1.66 [95% CI, 1.46e1.89]) and (2) clinically diagnosed dementia (cross-sectional: OR, 2.43 [95% CI, 1.48e4.01]; longitudinal: OR, 2.09 [95% CI, 1.37e3.21]) compared with persons without VI. Significant heterogeneity was explained partially by differences in age, sex, and follow-up duration. Also, some evidence suggested that individuals with CIM, relative to cognitively intact persons, were more likely to have VI, with most articles (8/9 [89%]) reporting significantly positive associations; however, meta-analyses on this association could not be conducted because of insufficient data.Discussion: Overall, our work suggests that VI is a risk factor of CIM, although further work is needed to confirm the association of CIM as a risk factor for VI. Strategies for early detection and management of both conditions in older people may minimize individual clinical and public health consequences. Ophthalmology 2021;128:981-992 ª 2020 by the American Academy of Ophthalmology Supplemental material available at www.aaojournal.org.With 2 billion people estimated to be 60 years of age or older worldwide by 2050, 1 the number of individuals with cognitive impairment (CIM) also is expected to triple by 2050. 2 Presently, cognitive decline is the fifth leading cause of disability for the elderly 3 and imposes a significant physical, psychological, economic, and social burden on patients, caregivers, families, and society. 4,5 Treatment strategies for CIM or dementia are limited. 6 Therefore, identifying potentially modifiable risk fac...

Visual Impairment, Eye Disease, and 3-Year Cognitive Decline: The Canadian Longitudinal Study on Aging

“…25,[50][51][52] For example, Hong et al 51 performed a prospective, population-based study of 3,654 participants of the Blue Mountains Eye Study in Australia and reported that VI was not associated with a ≥ 3 point decline in MMSE-Blind scores over 5 years (OR 0.84; 95% CI 0.40-1.79) or 10 years (OR = 1.09; 95% CI 0.52-2.30). This is in contrast to 4 longitudinal studies and one meta-analysis that have found a relationship between VI and cognitive function [12][13][14]53,54 and 1 study that found a relationship between visual acuity, used as a continuous variable, and cognitive decline. 55 Furthermore, several studies have found a relationship between VI and dementia or cognitive impairment [56][57][58][59][60] although not all.…”

Concurrent vision and hearing impairment associated with cognitive dysfunction in a population aged 85+ years: the Ural Very Old Study

“… 31 The finding of a concurrence of vision impairment and cognitive impairment concurs also with the results of precent meta-analyses. 33 34 …”

Hyperintensities of middle frontal gyrus in patients with diabetic optic neuropathy: a dynamic amplitude of low-frequency fluctuation study

“…To our knowledge, VEP have been used to observe the transmission of light signals to a subcortical nucleus and the visual cortex and this illustrates the extent of the visual pathway [ 37 ]. Damage to somewhere of visual pathway can lead to visual impairment, which affects the normal lives and leads to negative emotions [ 38 ], cognitive impairment [ 39 ] and poor motor perception [ 40 ]. Previous studies had demonstrated that there were retinal ganglion cells loss or apoptosis [ 41 , 42 ] and retinal nerve fiber layer thinner or loss in DR patients [ 43 ], but there were less than half of DR patients had optic neuropathy [ 5 ] and this neurodegeneration was an early event in the pathogenesis of DR [ 44 ].…”