Researchers investigated how a 40Hz light and sound therapy helps preserve myelin in patients with Alzheimer’s disease (AD). The therapy also shows potential for treating other conditions that involve myelin loss, such as multiple sclerosis. The corresponding study was published in Nature Communications.
Previous research suggests that 40Hz light and sound therapy significantly slows myelin loss in people with AD. Myelin is an insulating layer of protein and fats that forms around nerves to protect them and facilitate the transmission of electrical impulses. If myelin is damaged, neural circuit activity slows down. In the current study, researchers investigated how sensory stimulation preserves myelination.
To do so, they investigated the effects of 40Hz sound and light therapy on a mouse model of myelin loss- mice fed with chemical cuprizone. Altogether, the researchers studied four groups of mice: mice that received gamma stimulation but no cuprizone, mice that received cuprizone and constant light and sound (but not at 40 Hz), mice that received cuprizone and gamma stimulation, and unaffected mice.
After six weeks, the researchers assessed the mice for signs of myelination in their brains. Mice that were fed cuprizone but didn’t receive 40Hz gamma stimulation showed drastic levels of memory loss. Those, however, who were fed cuprizone and received 40Hz stimulation retained significantly higher levels of myelin and scored similarly to mice never fed cuprizone on some health measures. Gamma stimulation also helped protect numbers of oligodendrocytes- cells that produce myelin sheaths.
The researchers next assessed the cellular and molecular response to cuprizone demyelination using single-cell RNA sequencing technology. They found that astrocytes and microglia became very inflammatory in mice fed cuprizone who did not receive gamma stimulation and that gamma stimulation calmed the response. Direct observations of tissue also showed that microglia became more proficient in clearing away myelin debris.
“We show that multisensory gamma stimulation mitigates demyelination, promotes oligodendrogenesis, preserves functional integrity and synaptic plasticity, attenuates oligodendrocyte ferroptosis-induced cell death, and reduces brain inflammation. Thus, the protective effects of multisensory gamma stimulation on myelin and anti-neuroinflammatory properties support its potential as a therapeutic approach for demyelinating disorders.” wrote the researchers in their paper.
Sources: Neuroscience News, Nature Communications