Baycrest

8 • BrainMatters • Fall/Winter 2024 "Through neuromodulation of the anterior cingulate cortex, we expect to increase the brain's resilience against cognitive decline, which may delay or prevent onset of future dementia." Another modality is photobiomodulation (PBM), also known as low-level laser therapy. Only recently did scientists demonstrate the successful delivery of near-infrared light through the skull into the brain, and there are currently a few clinical PBM trials around the world, including at Harvard Medical School and by the U.S. Department of Veterans Affairs. PBM is harmless and easy to administer, and there are already commercial devices that can emit near-infrared light onto the skull. It has long been known that this type of light can reduce inflammation and accelerate tissue healing. Dr. Jean Chen, Canada Research Chair in Neuroimaging of Aging, believes she can demonstrate how PBM does this inside the brain. She says the evidence supporting PBM for Alzheimer's disease in humans is mounting, but the patient outcomes are mixed, much like for other non-invasive treatments. However, her research at Baycrest aims to change that. "To get more consistent results, one key question we must answer first is how different dosage factors such as light energy, light pulsation rate, wavelength, as well as skin tone can affect the efficacy of PBM." says Dr. Chen. "Without this knowledge, PBM cannot be tailored to each individual's needs, resulting in it being effective for some but not for others. This is the driver of our research." Mapping the effects includes determining whether cellular function and blood circulation improve. Eventually, when more is known, family doctors could potentially prescribe light therapy as a treatment for early dementia where patients can use the devices at home. Meanwhile, Dr Howard Chertkow, Director, Anne & Allan Bank Centre for Clinical Research Trials, and associate Dr. Tyler Roncero are running studies using transcranial direct current stimulation (tDCS), which circulates a very low-intensity current through the skull. Their tDCS studies have already been published in major journals and garnered enthusiastic support from the U.S. National Institute of Health to carry on a larger therapy study. In collaboration with U.S. labs, the team is conducting a Phase 2 clinical trial exploring the benefits of neuromodulation for primary progressive aphasia, a condition resulting from damage to parts of the brain that control speech and language. Another study is trying to improve walking ability for patients with progressive supranuclear palsy, a rare disease that affects walking, balance, eye movements and swallowing. Dr. Roncero, a scientific associate, has developed novel methods that direct the electricity deep into the brain where it can address these problems. Two other studies aim to improve cognitive function and language ability for patients with young onset Alzheimer's disease. "I like reminding people that tDCS isn't new and is already being used for some conditions, like depression and stroke. What we are investigating is whether these same benefits can be observed in people with different forms of dementia," says Dr. Roncero. "Of course, one benefit of using a technology already approved for clinical use is that participants who do experience a benefit have the option of purchasing their own machine for continued stimulation therapy at home." The Bresver Neuromodulation & Therapeutics Program is being coordinated by Dr. Roncero so that the labs can increasingly share results and work together. David Bresver, Bunni Bresver, Dr. Jed Meltzer

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