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The Bidirectional Relationship between Vision and Cognition: A Systematic Review and Meta-analysis
Vu TA, Fenwick EK, Gan ATL, Man REK, Tan BKJ, Gupta P, Ho KC, Reyes-Ortiz CA et al.. Ophthalmology, 2021-02-27
Topic: Brain imaging, connectivity and assessment
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 = 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, 1.84-3.07]; longitudinal: OR, 1.66 [95% CI, 1.46-1.89]) and (2) clinically diagnosed dementia (cross-sectional: OR, 2.43 [95% CI, 1.48-4.01]; longitudinal: OR, 2.09 [95% CI, 1.37-3.21]) 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.
Key findings
- Results Forty studies were included (n = 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, 1.84-3.07]; longitudinal: OR, 1.66 [95% CI, 1.46-1.89]) and (2) clinically diagnosed dementia (cross-sectional: OR, 2.43 [95% CI, 1.48-4.01]; longitudinal: OR, 2.09 [95% CI, 1.37-3.21]) 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.
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Study details
- Study designsystematic review
- Participants47
- Evidence strengthHigh
How this study scored 74/100
Published in a peer-reviewed journal, and it is a systematic review of all the studies on the question. Scored zero for effect reported because the record does not state it. We have no data on journal's citation record, times cited, citations per year, impact for its field and year, cited by studies here, still being cited, senior author's track record, institution's track record and multi-centre collaboration, so those were left out: it earned 43 of the 58 points we could judge it on, which is 74 out of 100.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Ophthalmology) |
| Journal's citation record | — / 4 | No journal record from OpenAlex — left out of this score |
| Study design | 12 / 12 | A systematic review of all the studies on the question |
| Strength of evidence | 5 / 5 | Rated “high” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 3 / 5 | 2021 — within 6 year(s) of the newest study here |
| Sample size | 1 / 4 | 47 participants |
| Effect reported | 0 / 3 | No effect size reported — scores zero (not stated in the record — scored 0) |
| Studied in people | 3 / 3 | Studied in people (participant count stated) |
| Randomised / blinded | 0 / 2 | A review of other studies — randomisation is not credited here |
| Times cited | — / 7 | No citation count (not found in OpenAlex) — left out of this score |
| Citations per year | — / 5 | No citation count or no year — left out of this score |
| Impact for its field and year | — / 6 | No field-weighted citation impact (OpenAlex has none yet) — left out of this score |
| Cited by studies here | — / 6 | Not yet checked against this library's citation graph — left out of this score |
| Still being cited | — / 4 | No yearly citation counts — left out of this score |
| Senior author's track record | — / 4 | Senior author's record not available — left out of this score |
| Institution's track record | — / 3 | No institution listed in OpenAlex — left out of this score |
| Multi-centre collaboration | — / 3 | Institutions not listed — left out of this score |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 33333104) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Points | 43 / 58 | Scored on 11 of 20 parts. We have no data for the rest, so they are left out: 43 of the 58 points we could judge it on is 74 out of 100. |
| Total | 74 / 100 | — |
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APA 7th
Vu, T. A., Fenwick, E. K., Gan, A. T. L., Man, R. E. K., Tan, B. K. J., Gupta, P., et al. (2021). The Bidirectional Relationship between Vision and Cognition: A Systematic Review and Meta-analysis. Ophthalmology. https://doi.org/10.1016/j.ophtha.2020.12.010
Vancouver
Vu TA, Fenwick EK, Gan ATL, Man REK, Tan BKJ, Gupta P, et al. The Bidirectional Relationship between Vision and Cognition: A Systematic Review and Meta-analysis. Ophthalmology. 2021. doi:10.1016/j.ophtha.2020.12.010. PMID: 33333104.
BibTeX
@article{vu2021-33333104,
author = {Vu, T. A. and Fenwick, E. K. and Gan, A. T. L. and Man, R. E. K. and Tan, B. K. J. and Gupta, P. and Ho, K. C. and Reyes-Ortiz, C. A. and others},
title = {{The Bidirectional Relationship between Vision and Cognition: A Systematic Review and Meta-analysis}},
journal = {Ophthalmology},
year = {2021},
doi = {10.1016/j.ophtha.2020.12.010},
pmid = {33333104},
url = {https://doi.org/10.1016/j.ophtha.2020.12.010}
}
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