Neurotransmitters after brain injury and their relationship with loss of consciousness

Objective To explore the difference in neurotransmitter levels between persons who had been comatose after a brain injury and healthy counterparts, and to explore the relationship between neurotransmitters and different states of consciousness. Methods A total of 52 persons with brain injury were analyzed retrospectively and divided into a coma group of 30 with Glasgow coma scale scores ≤9 and a sober group of 22 with scores >9. γ-GABA, 5-hydroxytryptamine, noradrenaline and dopamine levels were measured using encephalofluctuography and compared between the two groups. Results The levels of all of the neurotransmitters tested were significantly lower in the coma group than in the sober group. There were, however, no significant differences between the two groups in terms of relative levels of the neurorsmters. Logistic regression showed that dopamine deficiency is an important risk factor for coma after a brain injury. Conclusions Most neurotransmitters decrease significantly among those comatose after a brain injury. Dopamine deficiency seems to be a risk factor for the incidence of coma. Therefore, drugs or rehabilitation therapies which can improve dopamine levels can be considered to help coma patients regain consciousness. Key words: Brain injury; Coma; Encephalofluctuography; Neurotransmitters; Dopamine