We have long known the connection between vitamin D and mental health, however, new research may have found that the reason vitamin D deficiency has an effect on learning and memory may be due to its effect on PNNs. Perineuronal nets (PNNs), specialized extracellular matrix structures in the brain, act like a scaffolding that wraps around certain neurons, ensuring good communication between them. According to Dr. Thomas Burne, associate professor at the University of Queensland, “These nets form a strong, supportive mesh around certain neurons, and in doing so they stabilize the contacts these cells make with other neurons.”
Dr. Burne and his team used BALB/c mice, which are laboratory-bred albino mice, to find how vitamin D affects brain function. For 10 weeks the mice were fed either a diet with adequate vitamin D (1500 IU/kg) or a diet containing no vitamin D. The mice were then tested for hippocampal-dependent spatial learning using active place avoidance in addition to coordination and muscle function tests. The vitamin D deficient group was significantly less able to remember and learn when compared to the control group. There were no differences in rotarod or grip strength, indicating that vitamin D deficiency did not have an impact on muscle or motor coordination.
When their brains were later examined, they found the hippocampi in the vitamin D deficient group smaller than those in the control group. The vitamin D deficient group had a pronounced reduction in the number and strength of the connections of the perineuronal nets. The study, according to Dr. Burne, suggests that vitamin D plays a role in keeping the perineuronal nets stable.
The hippocampus is the first area affected by vitamin D deficiency because it is so active. This activity makes it more susceptible to vitamin D deficiency than other areas of the brain. According to Dr. Burne, "It's like the canary in the coalmine—it might fail first because its high energy requirement makes it more sensitive to the depletion of essential nutrients like vitamin D.”
These finding support another study that found that vitamin D deficiency is associated with reduced hippocampal volume and disrupted structural connectivity in humans. Vitamin D deficiency is associated with neurodegeneration and other brain issues. This study may help us to better understand the connection between vitamin D deficiency and brain function.