Normal-Tension Glaucoma Linked to Alzheimer’s Risk

Richard Mark Kirkner

October 06, 2022

CHICAGO — A large national study out of Taiwan has found that people with normal-tension glaucoma (NTG) are about 50% more likely to develop Alzheimer's disease (AD) than people without this form of the disease.

In a study presented here at the American Academy of Ophthalmology (AAO) 2022 Annual Meeting, Yu-Yen Chen, MD, PhD, of the Taichung Veterans General Hospital in Taichung City, reported on a population-based, retrospective cohort study using the Taiwan National Health Insurance Database. The study included 76,585 patients, 15,317 of whom had NTG; outcomes were evaluated over a 13-year period.

"From a public health perspective, policymakers are encouraged to enforce Alzheimer's screening for at-risk patients with NTG and to provide more substantial and integrated care," Chen said in presenting the results.

Chen noted that previous population-based cohort studies had inconsistent results and said that the cohort in this study was well matched in terms of age and gender.

Among the NTG group, rates of diabetes, hypertension, hyperlipidemia, and coronary artery disease were considerably higher than among the comparator group, Chen said, although rates of stroke were similar, between 10% and 11% in both groups.

The incidence of AD was also significantly higher among the NTG group, at 6.7% vs 4.2% (P < .0001), Chen said. This resulted in an adjusted hazard ratio of 1.52 (95% CI, 1.41 – 1.63; P < .0001), or a 52% greater risk of developing AD.

The study identified three risk factors among patients with NTG that were significant for the development of AD: age, female sex, and having had a stroke, Chen said. The type of glaucoma medication the patients were taking didn't factor into risk, she added.

"This is encouraging," Preeti Subramanian, PhD, said of the study in an interview. "We've been talking about there being common mechanisms for Alzheimer's and glaucoma, and this just moves us further in that direction. We can explore that further to better understand what the most common pathologies are." Subramanian is director of scientific programs in vision science at BrightFocus Foundation, an organization that sponsors research in AD, macular degeneration, and glaucoma.

While the sample size is substantial, Subramanian said the study lacked granular information about vision loss in the NGT patients. "We do not have enough information about to what extent glaucoma has progressed in these NGT patients and how that correlates with Alzheimer's disease, so that needs to be studied further," she said.

Dr Diane Bovenkamp

The findings also put ophthalmologists, primary care physicians, and neurologists on notice to use NTG as a biomarker for AD screening and to improve communications among themselves, added Diane Bovenkamp, PhD, BrightFocus vice president of scientific affairs. "This could involve giving more guidelines to doctors to pay attention to people who have normal-tension glaucoma to try and reduce or get the secondary diseases under control," she said.

Future studies into the relationship between NTG and AD should account for those comorbidities, Bovenkamp said.

Chen, Subramanian, and Bovenkamp have disclosed no relevant financial relationships.

American Academy of Ophthalmology (AAO) 2022 Annual Meeting: Poster 133. Presented September 29, 2022.

Richard Mark Kirkner is a medical journalist based in the Philadelphia area.

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