Distinct and Overlapping Metabolites Associated with Visual Impairment and Cognitive Impairment.

Background: Previous studies found that visual impairment (VI) is associated with higher risk of cognitive impairment, but the molecular basis of these conditions is unknown.

Objective: We aim to compare the metabolite associations of VI and cognitive impairment.

Methods: The study population with comprehensive measurements was derived from the UK Biobank study. Visual acuity worse than 0.3 logMAR units were defined as VI. Failure in one or more of the four cognitive tests was defined as cognitive impairment. A panel of 249 metabolites was measured using a nuclear magnetic resonance metabolites profiling platform. Logistic regression models were applied to compare metabolite associations with VI and cognitive impairment.

Results: 23,775 participants with complete data on visual acuity, cognitive tests and metabolomics, and without a history of neurological disorders at baseline were included. After adjusting for confounding factors, VI was significantly associated with cognitive impairment (odds ratio[OR] = 1.49, 95% confidence interval [CI]: 1.27-1.74, p < 0.001). After multiple testing correction (p < 9×10^-4), five metabolites including the ratio of omega-6 to omega-3 fatty acids (FAs) (OR = 1.18[1.10-1.27]), ratio of omega-3 to total FAs (OR = 0.84[0.77-0.91]), ratio of docosahexaenoic acid (DHA) to total FAs (OR = 0.86[0.80-0.94]), DHA (OR = 0.85[0.78-0.92]), and omega-3 FAs (OR = 0.84[0.77-0.91]) were uniquely associated with VI. Glycoprotein acetyls (OR = 1.06[1.03-1.10]) and alanine (OR = 0.95[0.92-0.98]) were exclusively associated with cognitive impairment. Albumin was identified as the common metabolite shared by the two phenotypes (OR = 0.90[0.85-0.95] for VI, and 0.95[0.92-0.98]) for cognitive impairment).

Conclusions: We identified distinct and overlapping metabolites associated with VI and cognitive impairment, unveiling their distinct metabolic profiles and potential common pathophysiology.