Brain cells, or neurons, communicate through electrochemical signals. The electrical signals travel down a neuron’s long axon to reach neurons in other areas of the brain in which it intends to communicate. A specialized type of brain cell called an oligodendrocyte produces myelin, a fatty protein that encases and insulates neuronal axons which allows electrical signals to propagate and travel efficiently to its target. In individuals with Alzheimer’s disease, myelin and oligodendrocytes are significantly altered which may contribute to the cognitive decline seen in the disease. That is, damaged or disrupted oligodendrocytes can lead to less myelin which impairs neuronal communication and cognition. In a recent study published in the journal Neuron, researchers investigated whether enhancing myelin can help prevent cognitive decline in a mouse model of Alzheimer’s disease.
Alzheimer’s disease affects up to 24 million people world-wide and is the leading cause of progressive dementia in older adults which leads to loss of memory and other important mental functions. While there is currently no cure for Alzheimer’s disease, there are major pushes in research and pharmaceutical development to lessen the harmful effects of Alzheimer’s and halt the progression of the disease.
In the current study, the researchers first investigated whether myelin loss occurred in Alzheimer’s disease patients. To do this, they quantified myelin in the brains of deceased individuals who were diagnosed with Alzheimer’s and compared them to the brains of age-matched individuals without the disease. They found that there was a significant decrease of myelin in brain areas important for cognition.
To study this further, the researchers then utilized a well-characterized mouse model of Alzheimer’s disease. They found that in this model, there was an accelerated degeneration of myelin in the mouse brains and that myelin loss was accompanied by poor performance on memory related cognitive tasks. The researchers then questioned whether rescuing myelin by administration of a drug that promotes myeline regeneration would improve cognition and increase myelin. They found that enhancing myelin renewal was associated with improved performance on the cognitive tasks. These findings provide insight into a relatively unexplored pharmaceutical target in Alzheimer’s disease and show that increasing myelin may help prevent cognitive decline.