Many neurobiological theories of the onset of depression rely on the lack of various neurotransmitters – chemicals through which arousal is transmitted from one nerve cell in the brain to another.
Between the processes of neurons – nerve cells in the brain – there is a narrow gap, a gap called a synapse, through which a signal is transmitted to another cell. The passage of a nerve impulse through the synapse from one cell to another is carried out with the help of one or another mediator. Before the transmitter is active, the message must change its shape – from an electrical impulse to a chemical signal.
Mediators accumulate in the transmitting process of the nerve cell, called the axon, are released from it, and through the cleft of the synapse they enter the processes (dendrites) of another nerve cell. Each neurotransmitter has a specific chemical structure, similar to a “connector” for specific, receiving contacts. After the message is transmitted from one cell to another, the “connector” is detached from the contact-receptor, and the mediator returns to the cleft of the synapse, where it is either destroyed under the influence of special substances, or is captured back by the transmitting cell.
In recent years, scientists believed that a special role in the development of depression mechanisms plays a decrease in the density and sensitivity of host receptors, with allied norepinephrine molecules and serotonin in the process of transmission of impulses.
In general , among the biological theories of the origin of depression today, the dominant theory is that depression occurs due to an insufficient amount of one of the neurotransmitters . If this theory is to be believed, the action of a number of antidepressants – modern drugs proposed for the treatment of depression – alleviates this deficiency, which in turn treats depression.
Development of psychopharmacology, the effectiveness of antidepressants of the new generation in many respects confirm the validity of this theory. The practice of monotherapy is partly based on its provisions – the careful selection and effective use of one drug. This practice allows, on the one hand, to significantly reduce the manifestation of undesirable side effects of the drug, and on the other hand , it provides the doctor with the possibility of fine, strictly individual selection of the dosage of the drug and the safe scheme of its use.