Even patients with early glaucoma may show signs of altered brain activity, such as impaired cerebrospinal fluid dynamics.
Even patients with early glaucoma may show signs of altered brain activity, such as impaired cerebrospinal fluid dynamics. Photo: Medical gallery of Blausen Medical, WikiJournal of Medicine.

Due to the neurodegenerative nature of glaucoma, the disease has the ability to affect certain aspects of brain function and activity. One part of the brain that may become altered in glaucoma is cerebrospinal fluid (CSF), which helps with clearing waste and can be facilitated by global brain activity. A recent study, presented earlier this month at the 2022 ARVO meeting in Denver, found that these effects may also not be limited to later stages of glaucoma; rather, the findings concluded that early glaucoma patients exhibited stronger CSF signals and CSF-blood oxygen level-dependent signal time coupling compared with those with advanced or no disease.

The study included 19 patients with early glaucoma, 19 with advanced glaucoma and 19 healthy controls. Most participants were in their early 60s. The researchers collected the CSF signal time profiles from the fourth ventricle and extracted global brain activity from blood oxygen level-dependent profiles in the entire gray matter. They explained that “the coupling between the CSF signals and the global brain activity was examined via cross-correlation at the four-second time lag, where more negative values indicate stronger coupling.” The correlations were also associated with the volumes of the anterior visual pathway observed in anatomical MRI.

The researchers observed a significant difference in the power of the low frequency (0.01Hz-0.03Hz) in the CSF signals and found that early glaucoma patients showed significantly greater power than those with advanced disease. Although not clinically significant, the power of the global brain activity showed similar trends.

Another parameter that differed significantly across the three groups: the CSF-blood oxygen level-dependent coupling at the four-second lag. Those with early glaucoma had stronger coupling than advanced glaucoma patients and healthy controls. The data also showed a correlation between coupling and the volume of the optic nerve and optic chiasm.

The findings confirmed the hypothesis that altered CSF dynamics and brain activity are prevalent in patients with glaucoma of any stage. It’s important to keep in mind that although a patient’s glaucoma may be mild, the threat of neurologic complications still remains.

Original abstract content © Association for Research in Vision and Ophthalmology 2022.

Bang JW, Yarsky E, Wollstein G, et al. Cerebrospinal fluid dynamics and its coupling with global brain activity are altered in early glaucoma patients. ARVO 2022 annual meeting.