This paper reviewed genetic, neurodevelopmental, and neurobiological perspectives to understand the etiology and relevant treatment approaches of schizophrenia. Although genetic and neurodevelopmental theories provide a substantial contribution to the etiology of schizophrenia, neurobiological one has its dominant stance in which it can explain causative mechanisms of schizophrenia, identify targets for treatment, and predict outcomes well. According to the neurobiology, onset and course of schizophrenia are well supported by the alterations in neurotransmitters such as dopamine or serotonin. Based on this mechanism, antipsychotics have been widely used as one of the treatment approaches for schizophrenia. By following up the degree of patients’ responses to antipsychotics, treatment outcomes could be evaluated or predicted. Although neurobiology seldom provides information about identification or prevention of risk factors about schizophrenia compared to genetic and neurodevelopmental approaches, it has well-established scientific foundations, ability to guide treatment, applicability across age and culture, and usefulness as a research framework.
Schizophrenia is a severe chronic mental disorder. It is diagnosed with delusions, hallucinations, disorganized speech and behavior, and negative symptoms [
Up until now, genetic, neurodevelopmental, and neurobiological theories have been regarded as major theories explaining the etiology of schizophrenia. It is important to note that these theories should not be envisioned as being separate from each other because they emphasize relatively different focuses on the development of schizophrenia. Therefore, this paper 1) briefly described these three major theories regarding etiology of schizophrenia; 2) described how the predominant theory, neurobiological theory, helped to explain or predict the onset and course of schizophrenia; 3) described relevant treatment methods and approaches to care based on the neurobiological theory; and 4) critiqued the neurobiological theory, as to several categories.
Through epidemiological studies (including those with twins, in adoption settings, and with siblings), the heritability of schizophrenia has been reported as being approximately 80% to 85% [
Along with the growing evidence of genetic contributions in schizophrenia, it has also been suggested that neurodevelopmental theory plays a pivotal role in understanding schizophrenia. This theory concerns about linkage of genetics, environmental exposures, and pathogenic occurrences [
With the development of neuroimaging, another possible explanation of the etiology of schizophrenia has been addressed. As per neurobiological theory, schizophrenia is regarded as the result of structural and functional abnormalities of the brain. Several domains such as the structure of the brain, physiology, chemistry, and neuropathology, are involved in this theory to explain schizophrenia. Etiological finding are as follows: 1) reductions in white matter structures, 2) functional alterations and impaired functional connectivity in prefrontal cortex, 3) reductions in neuronal and membrane integrity, and 4) neurotransmitter abnormalities [
Studies that use the neurobiological theory have identified alterations in neurotransmitters which occur at the onset of schizophrenia, helping to explain and predict some inconsistencies in the data. Alterations in neurotransmitter such as dysregulation of dopamine, glutamate, and serotonin, help to explain the onset of schizophrenia [
A review of the studies concluded that the identification of abnormalities in the prefrontal cortex in subjects at high risk for schizophrenia was well supported through functional brain imaging studies. The study also found evidence to suggest a number of brain structural abnormalities could be identified as potential markers of schizophrenia. However, there were not strong evidences to support structural abnormalities as illness-related markers in pre-schizophrenic individuals at high risk [
Neurobiological theory also helps to predict the course that schizophrenia might take. Every person with schizophrenia may experience different disease progress. However, there are common disease progress patterns. At first, typical psychotic symptoms such as hallucinations or delusions develop as neurotransmitters may not be regulated appropriately. After this acute stage is managed or treated by antipsychotics well, persons with schizophrenia will go through the next stage called as a chronic stage, characterized by lesser typical psychotic symptoms. However, during this chronic stage, a relapse may occur. Performing structural or functional brain imaging is a method to assess or evaluate the conditions of one’s brain. Therefore, through a series of functional brain imaging, prefrontal structural and neurochemical alterations can explain disease progress [
Treatment with antipsychotics can be relevant treatment methods according to neurobiological perspective. This drug treatment is currently the most popular way in managing schizophrenia in both clinical and community settings. According to neurobiological theory, schizophrenia is the result of neurotransmitter dysregulation such as: 1) an excess of dopamine, 2) reduced glutamate in the cerebrospinal fluid, 3) levels of gamma aminobutyric acid (GABA) expression in prefrontal cortex, or 4) reduced levels of serotonin [
Approaches to care that are guided by neurological theory include performing diagnostic procedures, predicting outcomes, identifying objective targets for treatments, and implementing antipsychotics medications. These approaches are performed according to the needs of individuals and their family members. Pre- and post-care for diagnostic procedures should be conducted, and evaluation and prediction of the outcomes should also be conducted. After closely evaluating the condition of a patient, selecting the most appropriate antipsychotic is very important. Therefore, likely course of a patient’s recovery should be explained to the patient, as well as the likely side-effects of the prescribed antipsychotics. Psychoeducation regarding etiology and medication management for patients and their family members should also be performed.
Through recent studies using the neurobiological theory to identify the etiology of schizophrenia, there have been many key findings which have advanced the scientific basis of the disease. A number of studies have focused on structural brain neuroimaging, identifying the alterations in the prefrontal lobe involved in schizophrenia. The fact that functional connectivity between prefrontal regions may be impaired has been suggested, and reductions in neuronal and membrane integrity have also been shown. Dysregulation of neurotransmitters have also been identified [
Neurobiological theory seldom leads to the identification of risk factor. However, neurobiological studies have indicated that pre-psychotic individuals experience alterations in brain structure and function, and then such individuals may move on psychosis [
Neurobiological theory has a high utility in guiding treatment. This theory employs antipsychotics treatment, the most widely used method to manage schizophrenia. Psychopharmacology based on the understanding of the neurophysiology and neurochemistry, especially focusing on neurotransmitters, can guide effective treatment methods for patients who have schizophrenia [
Neurobiological theory pays little attention to the customer/patient’s perspective and needs because this theory views the etiology of the schizophrenia as structural, functional, and neurochemical alterations in the brain. This theory only focuses on the brain, itself, and is based on the biological mechanisms and findings. Moreover, the health care provider’s perspective is more prevalent in this theory because it is guided antipsychotics treatments and assesses and evaluates outcomes in patients. However, this theory describes well the etiology of schizophrenia related to patient’s symptoms and treatment needs.
This theory has facility across cultures. Whereas, genetic theory is not entirely generalizable (because the role of several genes has not been established in all ethnic groups), several studies identified that structural and functional alterations in the brain are identified, regardless of one’s culture or ethnic group, or gender. However, as current studies focus on the issues of gender difference, there have been some inconsistent findings in the brain features in male versus females with schizophrenia [
This theory is applicable to all people, regardless of their age. The age of onset of schizophrenia is adolescent or early-adult periods [
This theory has little shortcomings in terms of ethical considerations. Genetic theory focuses on hereditability of the schizophrenia and certain gene identification. Treatment methods are gene replacement therapy or genetic consultation. Moreover, neurodevelopmental theory focuses on adverse environmentally exposures during perinatal periods. Thus, a patient’s family members may have sort of guilt feelings about the fact that certain genes are predominant to cause schizophrenia and a patient’s disease might be preventable only if avoiding perinatal or environmental risks. However, this neurobiological theory may not have ethical conflicts because this explanation is rooted on the abnormalities of the brain, itself.
Overall, the neurobiological theory is useful as a framework for research because it has strong scientific evidence and applies across age and cultures. Moreover, the ability to guide treatment methods is predominant. Therefore, it has a strong power in studying antipsychotic medication intervention research studies. For example, diverse racial/ ethnic groups and diverse age groups can be included to examine the effectiveness of medication. Most nursing-related research studies focus on psychosocial aspects, not only neurobiological aspects of the etiology of schizophrenia to study the phenomenon of the disease. Therefore, this theory has limitations because it focuses on the brain, itself, and is based on the biological mechanisms and findings.
Of the three theories (genetic, neurodevelopmental, and neurobiological theories), which theory is the right answer regarding the etiology of schizophrenia may be difficult, because each theory may emphasize a different aspect of the disease. However, of these, the neurobiological theory is the predominant theory in explaining the etiology of schizophrenia. The neurobiological theory defines schizophrenia as a result of abnormal dysfunctions, or abnormal structures of the brain. This theory: 1) has a strong scientific foundation, 2) has high utility in guiding treatment, and 3) is appropriate regardless of a patient’s age or culture. Moreover, there are few ethical considerations regarding its use when compared with other theories; therefore, it’s more useful than all others.
Kim, M. (2016) Understanding the Etiology and Treatment Approaches of Schizophrenia: Theoretical Perspectives and Their Critique. Open Jour- nal of Psychiatry, 6, 253-261. http://dx.doi.org/10.4236/ojpsych.2016.64030
GWAS: Genome-wide association studies.
COMT: Catechol-O-methyl transferase.
DISC1: Disrupted in schizophrenia 1.
NRG1: Neuregulin 1.
GABA: Gamma aminobutyric acid.
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