Normal tension glaucoma is associated with cognitive impairment

Abstract

Purpose : Normal-tension glaucoma (NTG) and Alzheimer’s dementia (AD) are incurable age-associated neurodegenerative diseases with a significant global disease burden. Recent research has suggested an association between NTG and AD, although previous studies are significantly limited by small sample sizes or retrospective design. We performed a cross-sectional cognitive screening study to investigate whether dementia is more strongly associated with NTG than high-tension glaucoma (HTG) in glaucoma patients randomly sampled from a large, multi-national glaucoma registry.

Methods : 597 age- and sex-matched NTG and HTG participants of ≥65 years of age were randomly sampled from the Australian and New Zealand Registry of Advanced Glaucoma. For the purpose of this study, NTG was defined as pre-treatment intraocular pressure (IOP) of ≤21 mmHg, and HTG was defined by any single IOP measurement of ≥25mmHg. All participants were contacted by telephone requesting participation in this study. Reasons for exclusion from this study included: participant deceased, poor hearing, poor English, declined participation, inability to contact, and severe dementia. Following exclusion, cognitive screening was performed on a total of 290 participants using the Telephone Version of the Montreal Cognitive Assessment (T-MoCA). Cognitive screening scores were compared between NTG and HTG cohorts. Cognitive impairment was defined as a T-MoCA score of <11/22. Using age as a covariate, T-MoCA scores were compared between NTG and HTG samples using logistic and linear regression. Subgroup analysis was subsequently performed with re-inclusion of participants initially excluded due to inability to perform cognitive screening as a result of severe dementia.

Results : A total of 290 participants completed cognitive assessment. Baseline demographics and clinical parameters were similar between NTG and HTG cohorts. Cognitive impairment was more prevalent in the NTG cohort than the HTG cohort (p=0.022; OR=2.8 [95% CI=1.2-6.7]). This association was strengthened following re-inclusion of participants with severe dementia (p=0.013; OR=2.9 [95% CI=1.2-6.6]) who were designated as cognitively impaired for this analysis.

Conclusions : This study demonstrated an association between NTG status and poorer cognition, supporting the hypothesis that at least some cases of NTG may share patho-aetiological features with dementia syndromes such as AD.

This is a 2020 ARVO Annual Meeting abstract.