The Relationship Between Diabetic Retinopathy and Cognitive Impairment

Abstract

OBJECTIVERecent studies have shown an increased risk for cognitive impairment and dementia in patients with diabetes. An association between diabetic retinopathy (DR) and retinal microvasculature disease and cognitive impairment has been reported as potential evidence for a microvascular component to the cognitive impairment. It was hypothesized that severity of DR would be associated with cognitive impairment in individuals with type 2 diabetes.RESEARCH DESIGN AND METHODSThree hundred eighty patients with type 2 diabetes were recruited from a population-based eye screening program and grouped by severity of DR as follows: no/mild DR (n = 252) and proliferative diabetic retinopathy (PDR) (n = 128). Each participant underwent psychosocial assessment; depression screening; ophthalmic and physical examination, including blood assays; and cognitive assessment with the Addenbrooke's Cognitive Examination-Revised (ACE-R), Mini-Mental State Examination (MMSE), and the Mini-Cog. General linear modeling was used to examine severity of DR and cognitive impairment, adjusting for confounders.RESULTSSeverity of DR demonstrated an inverse relationship with cognitive impairment (fully adjusted R2 = 0.415, P < 0.001). Ethnicity contributed most to the variance observed (16%) followed by education (7.3%) and retinopathy status (6.8%). The no/mild DR group had lower cognitive impairment scores on ACE-R (adjusted mean ± SE 77.0 ± 1.9) compared with the PDR group (82.5 ± 2.2, P < 0.001). The MMSE cutoff scores showed that 12% of the no/mild DR group (n = 31) had positive screening results for dementia or significant cognitive impairment compared with 5% in the PDR group (n = 6).CONCLUSIONSPatients with minimal DR demonstrated more cognitive impairment than those with advanced DR. Therefore, the increased prevalence of cognitive impairment in diabetes may be associated with factors other than evident retinal microvascular disease.

Severe Diabetic Retinal Disease and Dementia Risk in Type 2 Diabetes

“…A longitudinal study (n=180), reported that the presence of diabetic retinopathy assessed prior to coronary surgery was associated with an increased risk of cognitive decline after 6 months following surgery [9]. Other studies reported no association between diabetic retinopathy and cognition [11,12] nor with cognitive decline after 4 years [11]. Possible explanations for the negative findings of some of these studies include limited sample sizes (consequently including few retinopathy cases e.g.…”

“…[11], different levels of severity of diabetic retinopathy (i.e. also including non-proliferative diabetic retinopathy a less severe form of diabetic retinal disease) [11] and exclusion of patients with dementia and stroke which could lead to an underestimate of the level of cognitive impairment [12]. Of note the relation between diabetic retinopathy and cognition has also been studied in patients with type 1 diabetes.…”

“…It is of particular relevance to study this association in patients with existing T2DM, as diabetes can lead to pronounced microvascular changes. Previous studies observed associations between diabetic retinal disease and lower cognitive performance [8–10], but results are inconsistent [11,12]. However, these studies were mostly cross-sectional and the possible prospective link between diabetic retinal disease and the incidence of dementia has not been studied previously.…”

Near Vision Impairment Is Associated With Cognitive Impairment in Type 2 Diabetes

“…20 Associations between DR and cognitive impairment have been reported for an older and population-based sample of a different ethnicity in which only a third had diabetes. 20 Associations between DR and cognitive impairment have been reported for an older and population-based sample of a different ethnicity in which only a third had diabetes.…”

Cognitive decline in newly diagnosed Type 2 Diabetes and the effect of good glycemic control on cognitive function

“…There were several studies that showed association between diabetic retinopathy and cognitive impairment, with a near threefold increased risk of cognitive impairment in patients with diabetic retinopathy compared to those without. (20) In our study population, out of the 140 patients, 30% had MMSE scores <24, thus demented at baseline. The highest score was 29 and the lowest was 13.…”