An animal study has led to greater understanding of the complex causes of cognitive decline in the aging brain. Cognitive decline is a factor in aging, but can this decline be prevented?  A study measured l-tyrosine nitration to investigate the role of Vitamin D in the aging brain.

The world population is aging. We can all expect to live longer, particularly if we live in developed countries. The percentage of people 80 and older is projected to increase fourfold over the next 50 years. And the proportion of people who live beyond the age of 100 is growing rapidly.

However, aging brains often suffer cognitive decline. Forgetfulness, inability to maintain focus, and a reduced capability to solve problems are common to all aging brains. Mild cognitive decline is an expected part of aging. But cognitive decline doesn’t affect all brains equally.

Cognitive decline can be caused by a variety of factors. Oxidative stress, which leads to free radicals damaging healthy cells, is one factor. Nitrosative stress is also a factor in cognitive decline. This occurs when nitrogen species act with reactive oxygen species to damage the healthy brain cells. But where does l-tyrosine fit into this picture?

A study from the Sanders Brown Center on Aging, University of Kentucky, examined the links between vitamin D deficiency and nitrosative stress. Can measuring l-tyrosine levels in the vitamin D-deficient brains help predict cognitive decline? Researchers J Keeney, S Forster, et al, developed an animal study to investigate.

Can measuring l-tyrosine combat cognitive decline?

Middle aged male rats were divided into three groups and fed either low vitamin D food, or high vitamin D food.  The diet continued for 5 months, then their brains were examined for evidence of oxidative and nitrosative stress.

One indication of nitrosative stress is the production of nitrol-tyrosine, which is caused by l-tyrosine nitration, which is a chemical process. L-tyrosine is an amino acid, produced in the body from phenylalanine. It is vital to general metabolism.

In this rat study, the low vitamin D group had much higher levels of nitrol-tyrosine. The study proved that vitamin D deficiency resulted in significant nitrosative stress in the brain, and that this nitrosative stress may cause cognitive decline.

The researchers concluded that proper nutrition, with adequate levels of vitamin D that help prevent l-tyrosine nitration, are necessary to prevent cognitive decline.