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Variation in retinal microvascular parameters is associated with mild cognitive impairment and Alzheimer’s disease
Author(s) -
O'Neill Rachael Ann,
Maxwell Alexander Peter,
Hogg Ruth E,
Passmore Anthony Peter,
Quinn Nicola,
Kee Frank,
Young Ian,
McKay Gareth,
McGuinness Bernadette
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.040893
Subject(s) - dementia , confounding , cognition , medicine , retinal , audiology , logistic regression , montreal cognitive assessment , cognitive decline , cardiology , gerontology , disease , psychology , ophthalmology , psychiatry
Background Alzheimer's disease (AD) is a neurodegenerative condition characterised by cognitive decline. Mild Cognitive Impairment (MCI) represents a transitional state between ageing normally and all forms of dementia, although those with MCI will not automatically convert to dementia. The retinal and cerebral microvasculature share similar embryological origins and physiological characteristics. Improved imaging technologies enable non‐invasive measurement of retinal microvascular parameters (RMPs). We investigated associations between RMPs and cognitive function in participants with AD and MCI. Method RMPs (arteriolar/venular diameter, fractal dimension, vessel tortuosity) were measured from optic disc centred fundus images and analysed using semi‐automated software. Thirty‐four MCI and thirty‐two AD participants were recruited for the study from the Belfast Health and Social Care Trust memory clinics. Nine MCI and thirteen AD participants were excluded as their retinal images were of insufficient quality for image analysis. Associations were assessed by logistic regression with comparison to an age and sex‐matched control group from the NICOLA study as the reference category. Models were adjusted for potential confounders including smoking, diabetes, hypertension, total cholesterol and Mini Mental State Exam (MMSE) score. P<0.05 was considered significant. Result Data were included for 126 participants with cognitive function measures and sufficient retinal images. Twenty‐five participants had a clinical diagnosis of MCI and nineteen AD. Eighty‐two age and gender‐matched controls with no previous history of cognitive impairment, and MMSE and Montreal Cognitive Assessment scores >26/30 were included. Decreased arteriolar fractal dimension (OR: 0.30; 95%CI: 0.10, 0.91; P=0.03) was significantly associated with AD in all models. Decreased venular fractal dimension and both arteriole and venular diameter were significantly associated with MCI in all models (P <0.05). No further associations were detected (P >0.05). Conclusion Our findings identified variation in RMPs in association with MCI and AD in an older population. Additionally, previous studies have reported associations between reduced fractal dimension with MCI and AD. We were able to replicate these associations in unadjusted analyses, and following adjustment for confounders. These non‐invasive retinal measures may help identify mechanistic pathways of microvascular complications early in the disease process in individuals at increased risk of MCI and AD.