Vitamin D, found in foods such as mushrooms, eggs, and fatty fish (salmon, herring, sardines, etc), are essential for brain and immune system health. Researchers at the University of Queensland have shed light on how deficiencies lead to disorders such as depression and schizophrenia. Associate Professor Thomas Burne at the University of Queensland’s Brain Institute led the studies and his team published in Brain Structure and Function and Trends in Neuroscience.
"Over a billion people worldwide are affected by vitamin D deficiency, and there is a well-established link between vitamin D deficiency and impaired cognition," according to Dr Burne.
Burne continued, "Unfortunately, exactly how vitamin D influences brain structure and function is not well understood, so it has remained unclear why deficiency causes problems."
The researchers team found that vitamin D levels affect a type of 'scaffolding' in the brain, called perineuronal nets. Burne describes the nets, “These nets form a strong, supportive mesh around certain neurons, and in doing so they stabilize the contacts these cells make with other neurons".
Researchers removed vitamin D from the diet of a group of healthy adult mice, and after 20 weeks observed a significant decline memory and cognition compared to a control group. The vitamin D deficient group had a pronounced reduction in perineuronal nets in the hippocampus, the brain region crucial to memory formation, noting a reduction in number and strength of connections between neurons. Dr Burne's team suggest that vitamin D plays an important role in keeping perineuronal nets stable, and that reduction in vitamin D enables this scaffolding to be more suspectable to enzyme degradation.
Burne concludes, “As neurons in the hippocampus lose their supportive perineuronal nets, they have trouble maintaining connections, and this ultimately leads to a loss of cognitive function."