In the case of schizophrenia, the evidence suggests that such patients usually tend to have low levels of norepinephrine and high levels of serotonin (Schimelpfening, 2021). There is also a hypothesis in regards to dopamine’s role in the development and progression of the disease, which is induced by the proper functioning of the system (Schimelpfening, 2021). Dopamine plays a central role in memory formation, which was introduced later in the evolutionary stage of humans, where the persistent hunting style led to central nervous system changes.
The coverage of large geographical areas forced humans to develop stronger mapping capabilities by memorizing key features of the corresponding territory, which required stronger utilization of dopamine. In other words, the memory issues of schizophrenia can be the result of improper functioning of dopamine and dopaminergic system within the brain.
Bipolar I disorder is also implicated by neurotransmitter imbalance, where there is no clear indication of whether dopamine or serotonin have a direct causal relationship with the disease. However, it is evident that high levels of noradrenaline are strongly associated with mania, which is the key distinguishing factor of Bipolar I and Bipolar II, where the former has a full manic episode, and the latter has only hypomanic episodes. In other words, the implication of neurotransmitters can be manifested in either a certain imbalance between all of three elements or over expression or high concentration of norepinephrine, which induces a more prominent fight-or-flight response, which, in turn, leads to a manic episode.
In the case of a major depressive disorder or depression, all three neurotransmitters play a critical role in the development of the disease. Major depression is a common mental disorder that is one of the most common causes of disability (Schimelpfening, 2021). This disease occurs in all age groups and affects people of both sexes in any region of the world. The experience of recent decades has shown that the prospects for studying depression are associated with its neurobiology.
The molecular hypothesis is widely used to explain the pathogenetic mechanisms of depression. According to the latter, adverse environmental factors, such as stress, affect genetic vulnerability, which causes maladaptive changes in the chain of neurotransmitters, among which monoamines play the main role. Most of the available advances in the treatment of the disease have also implemented the effects on the deciphered mediator mechanisms of pathogenesis. Dopamine affects depression because it is responsible for inducing a sense of motivation, which drives the majority of behavioral tendencies (Schimelpfening, 2021). The reduction in dopamine levels can lead to a reduced desire for normal behaviors.
Similarly, norepinephrine, which both hormone and neurotransmitter, take part in the fight-or-flight response, where its low concentration makes a person less active and dynamic. However, the serotonin system is one of the most important systems of cerebral neuromodulation involved in the pathogenesis of depression. This neurotransmitter system has a long evolutionary history and is involved in a variety of behavioral acts and emotional manifestations (Schimelpfening, 2021).
In order to better understand the integration of the serotonin system into the brain processes of mood regulation, one should, first of all, consider the available data on the influence of different cerebral regions on affective manifestations. Thus, executive functions, including the modulation of emotional behavior, which may be related to the formation of cognitive symptoms of depression, are associated with hypoactivation of the left frontal cortex.
Reference
Schimelpfening, N. (2021). The chemistry of depression: What is the biochemical basis of depression? Verywellmind. Web.