Pyridoxine (Vitamin B6) is a co-factor for glutamic acid decarboxylase, an enzyme that converts glutamate to GABA. Therefore, the concurrent increase in the excitatory neurotransmitter glutamate, and decrease in inhibitory neurotransmitter, GABA, resultant from B6 deficiency, may manifest itself in the form of seizures.
Causes
Lack of pyridoxine in the diet
Another cause of vitamin B6 deficiency is the use of the tuberculostatic medication isoniazid, and for this reason, it is recommended to supplement with vitamin B6 when using this drug.
Grumpiness and irritability are also often symptomatic of a deficiency according to "Body, Mind, and the B Vitamins" by Ruth Adams and Frank Murray.