Prevalence of vitamin A deficiency. Vitamin A deficiency (VAD) is a lack of vitamin A in humans. It is common in poorer countries but rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of VAD.revalence of vitamin A deficiency. Vitamin A deficiency (VAD) is a lack of vitamin A in humans. It is common in poorer countries but rarely seen in more developed countries. Nyctalopia (night blindness) is one of the first signs of VAD.
Both lithium and valproate have been reported to increase rat CSF GABA levels. Regarding valproate, animal studies reported that it enhances GABA levels, GABA synaptic release, GAD activity, neuronal GABA responsiveness, and inhibits GABA-T in several brain regions.
It is essential for brain metabolism. 1  GABA functions as a neurotransmitter naturally produced in the brain that functions as part of the nervous system. 2  GABA works to support cellular function, especially in the brain. 3  GABA is an amino acid found in brewer's yeast.ABA is formed by the enzyme glutamic acid decarboxylase with a little help from Vitamin B6. GABA is an inhibitory neurotransmitter in the central nervous system capable of blocking cell-to-cell transmissions.