Learning and Memory Affected
In the new research, published in the Journal of Nutrition, researchers conducted a six-month dietary intervention to compare the cognitive performance of mice that were fed a low-vitamin K diet and those receiving a standard diet.
The research team focused on menaquinone-4, a form of vitamin K prevalent in brain tissue, and found significantly lower levels of this nutrient in the brains of the vitamin K-deficient mice. This deficiency is associated with noticeable cognitive decline as measured in a series of behavioral tests designed to assess their learning and memory.
In one such test, the novel object recognition test, the vitamin K-deficient mice showed a diminished ability to distinguish between familiar and new objects, a clear indication of impaired memory. In a second test, to measure spatial learning, the mice were tasked with learning the location of a hidden platform in a pool of water. The vitamin K-deficient mice took considerably longer to learn the task compared to their counterparts with adequate vitamin K levels.
When the researchers then examined the mice brain tissue, they found significant changes within the hippocampus, a brain region crucial for learning and memory. Specifically, they observed a reduced number of proliferating cells in the dentate gyrus of the hippocampus in the vitamin K-deficient mice. This decrease translated to fewer newly generated immature neurons, a process known as neurogenesis. “Neurogenesis is thought to play a critical role in learning and memory, and its impairment could directly contribute to the cognitive decline observed in the study,” Zheng says.
Adding another layer of complexity, the researchers also found evidence of increased neuroinflammation in the brains of the vitamin K-deficient mice.
“We found a higher number of activated microglia, which are the major immune cells in the brain,” says Zheng. While microglia play a vital role in maintaining brain health, their overactivation can lead to chronic inflammation, which is increasingly recognized as a key factor in age-related cognitive decline and neurodegenerative diseases.
