Relation between vitamins of the b complex, GABA and glutamate, and their role in neurocognitive disorders -Brief review

Abstract

Vitamins, especially the water-soluble complex of vitamins B, are highlighted in the daily clinical practice. Numerous studies emphasize the need for supplementation, mainly in groups with deficiency of these vitamins, such as the elderly, pregnant women, children and patients with diseases associates with cognitive disorder. Thiamine (B1), a vitamin of the diet, is an important cofactor for the three key enzymes involved in the citric acid cycle and the pentose phosphate cycle. Pyridoxine (B6) and cobalamin (B12) act in the CNS as a cofactor in the metabolism reactions of homocysteine. Deficiency of some neurotransmitter precursors can also cause symptoms of attention deficit hyperactivity disorder in children, especially amino acid and vitamin B deficiency. Inhibitory and excitatory neurotransmitters regulate diverse behavioral processes, including sleep, learning, memory and sensation of pain. They are also implicated in many pathological processes, such as epilepsy and neurotoxicity. Studies suggest that the excitatory amino acids may play a role in learning and memory. The binding of glutamate to its receptor triggers molecular and cellular events associated with numerous physiological and pathophysiological pathways, including the development of an increased sensation of pain (hyperalgesia), brain neurotoxicity or synaptic alterations involved in certain types of memory formation. Between the two major classes of neuroactive amino acids, γ-aminobutyric acid (GABA) is the major inhibitory amino acid. It is known that GABA plays a fundamental role in encoding information and behavioral control, in the regulation of motor function and in motor learning. The inter-relationships between diet, the brain and behavior are complex. However, micronutrients are known to have a direct influence on cognitive function through their involvement in the energy metabolism of neurons and glia cells, the synthesis of neurotransmitters, receptor binding and the maintenance of membrane ion pumps.