Kamila Ginyaz Kazimova

Abstract. The article provides information about depression, noting that it is a widespread, chronic, and recurrent mental disorder. It states that genetic factors play a key role in the etiology of depression, as research has shown that the risk of depression is higher in monozygotic twins compared to dizygotic twins. The concordance rate of depression in monozygotic twins ranges between 45-50%, whereas in dizygotic twins, it varies between 15-20%. Additionally, the article mentions the monoamine hypothesis, which attempts to explain the role of monoamine neurotransmitter deficiency in the biological etiology of depression. However, recent research findings indicate that neurotransmitters alone cannot fully explain the etiology of depression. Hypotheses regarding the etiology of depression have now progressed to the molecular level and are being explained through the gene expression theory. Neuroplasticity also holds a significant place among the neurobiological factors of depression. In depressive individuals, the brain’s ability to form new neural connections and modify existing ones – i.e., neuroplasticity – is weakened. The article also highlights that one of the main causes of depression is an imbalance in neurotransmitters in the brain. Moreover, modern research suggests that the inflammation theory is also crucial in the development of depression. According to this theory, inflammatory processes lead to changes in certain regions of the brain, exacerbating depressive symptoms. Structural changes in the brain, particularly in the hippocampus, amygdala, and prefrontal cortex, are associated with emotional dysfunction and memory problems. At the end of the article, it is emphasized that research into the genetic and neurobiological theories of depression is ongoing, and each of these studies opens new perspectives in terms of both psychotherapy and prevention. It is also underlined that these findings hold significant potential for the application of personalized approaches to depressive individuals in the future.

Key words: Depression, genetic factors, genes, neurotransmitter, neuroplasticity, neurobiological theories, monoamine theory, inflammation theory