Vitamin D deficiency related to loss of brain plasticity

Research from the University of Queensland could explain why vitamin D is vital for brain health and how deficiency causes disorders such as depression and schizophrenia.

Associate Professor Thomas Burne of the Queensland Brain Institute of UQ led the studies, which lay the groundwork for research on improving prevention and treatments.

"More than a billion people in the world suffer from vitamin D deficiency and there is a well-established link between vitamin D deficiency and cognitive impairment," said Dr. Burne.

"Unfortunately, it is unclear how vitamin D influences the structure and function of the brain, so why is deficiency a problem?"

Dr. Burne's team discovered that vitamin D levels affect a type of "scaffolding" in the brain called the perineuronal network.

"These networks constitute a strong and favorable mesh around certain neurons and, in doing so, they stabilize the contacts that these cells establish with other neurons," he said.

The researchers removed vitamin D from the diet of a group of healthy adult mice and, after 20 weeks, found a significant decrease in their ability to memorize and learn compared to a control group.

Dr. Burne explained that the vitamin D deficient group exhibited a pronounced reduction in perineuron networks in the hippocampus, the crucial brain region for memory formation.

"There was also a clear reduction in the number and strength of connections between neurons in this region."

UQ researchers suggest that as vitamin D levels decline, some enzymes are no longer controlled and begin to break down into perineuronal networks. (Nick Valmas, UQ) Dr. Burne's team proposes that vitamin D plays an important role in the stabilization of perineuronal nets and that, as vitamin D levels decline, this "scaffold" is more easily degraded by enzymes.

"When the neurons of the hippocampus lose their perineuronal networks, they have trouble maintaining the connections, which ultimately results in a loss of cognitive function."

Associate Professor Burne said that the hippocampus could be the most strongly affected by vitamin D deficiency because it is much more active than other brain regions.

"It's a bit like the canary in the coal mine: it may fail first because its high energy requirements make it more sensitive to the depletion of essential nutrients like vitamin D.

"Curiously, the right side of the hippocampus was more affected by vitamin D deficiency than the left side."

Associate Professor Burne said that loss of function in this area could be an important factor in schizophrenia, including severe memory deficits and a distorted perception of reality.

"The next step is to test this new hypothesis on the link between vitamin D deficiency, perineuronal nets and cognition," he said.

"We are also particularly pleased to have discovered that these nets can change in adult mice.

"I hope that because they are dynamic, there is a chance that we can rebuild them, which could pave the way for new treatments."

This article has been republished from documents provided by the University of Queensland. Note: Content may have changed for length and content. For more information, please contact the cited source.

Reference: Mayne, P.E., and Burne, T.H.J. (2019). Vitamin D in synaptic plasticity, cognitive function and neuropsychiatric disease. Trends in Neurosciences, 0 (0). https://doi.org/10.1016/j.tins.2019.01.003