Schizophrenia is a complex mental illness and from intracellular processes to the level of observable behavior it has challenged science. Until now, researchers have been busy finding the single factor that is the cause of schizophrenia but they have not succeeded. It’s a chronic condition with a recurring psychotic illness that starts generally at young age and most of the time lasts for a lifetime (Carpenter & Buchanan, 1994, p. 682).
The key features of schizophrenia include paranoia, hallucination, delusions, and cognitive dysfunction. These defining features produce abnormalities in a number of areas including emotions, thoughts, and cognitions. The psychotic symptoms of schizophrenia have an unknown onset with associated features including customary association, and failure to logic and reality. Psychosis is not the loss of these functions rather it’s malfunctioning.
Exploring this disorder shows that researchers have worked in different domains to explore the causes of schizophrenia. The major areas explored by researchers include the role of genes in causing schizophrenia, the chemical activities influencing brain chemistry and distortion in the brain of schizophrenics. So to explain the causes of schizophrenia it is important t discuss cognitive and biological explanations of schizophrenia (APA, 2007).
Cognitive Explanation of Schizophrenia
Schizophrenia is characterized by distortions in thoughts, attention, language, and perception. According to the cognitive school of thought, these are the causes of this disorder rather than the consequences of schizophrenia. This school of thought explains that different features of schizophrenia appear when the individual experiences them. When any person is confronted by any sort of delusions or hallucinations he turns to some close one, but when it is denied by them then the patient thinks that they are hiding the truth from them. Individuals started to reject all sorts of feedback and begin to think that they are being persecuted. In other words, we can say that schizophrenics follow a rational path to madness (Comer & Whitford, 1996, p. 473).
Perceptual Errors
Researchers have added the literature that schizophrenics do experience perceptual errors in the case of hallucinations and delusions. But the misinterpretation of such sensory experience produces the syndrome of schizophrenia.
Drury, Robinson, and Birchwood (1998) found that people with schizophrenia have difficulty interpreting the intentions and beliefs of others. This explanation is also supported by the theory presented by Frith who was in view that schizophrenics have difficulties in the meta representation of thoughts.
Neuropsychological Model of Schizophrenia
According to Hemsley, one of the major root causes of schizophrenia is the breakdown of already stored information in the minds of schizophrenics and upcoming new information to them from their surrounding.
According to this theory, the schemas of schizophrenics are affected due to sensory overload and inculcate in the mind of schizophrenics that all the new information is highly relevant and thus explains the delusions. Although it does not explain schizophrenia yet it provides the explanations that how the symptoms originate.
Information Processing Overload
It was thought that the reason for poor performance by people with schizophrenia is their lack of theory of mind but later Drury, Robinsons, and Birchwood found that the cause of poor performance in schizophrenics is due to overload of information processing because of the complicated nature of the task. This perspective rejected the concept of FRith’s meta representation and suggests that these people have difficulty in attending to the relevant information and filtering it that is selective attention. Hemsley’s theory related to poor perception and memory integration is also strengthened by the cognitive explanation that suggests that people with schizophrenia mistook their own voices and inner speech for that of some other person.
Cognitive Dysfunction
A cognitive explanation suggests that this disorder is not a domain-specific deficit rather it is an impairment related to the complete integration of brain function. Such impairment decreases the likelihood of individuals dealing with stress in life and also maximizes the individual vulnerability to the aversive life experiences that lead to dysfunctional behaviors of individuals. Reality testing decreases and cognitive dysfunctioning increases in people with schizophrenia that develop some dysfunctional cognitive schema that is manifested by hallucinations and delusions.
The cognitive explanation of schizophrenia is not comprehensive rather it only explains the origin of symptoms so this explanation must combine with the biological one to explain this disorder better.
Biological Explanation of Schizophrenia
The biological explanation of schizophrenia explains that schizophrenia has an organic cause although it does not deny the importance of another school of thought yet it provides an explanation for its causes. It involves genetic and brain chemistry in explaining schizophrenia. A single generalization can be drawn that explains genes are responsible for causing schizophrenia. Although it is not a single gene rather multiple genes are involved. For this purpose family, twin, and adoption studies provide strong evidence (Comer & Whitford, 1996, p. 473).
Family Studies
There are a number of researchers that provide evidence that schizophrenia runs in families which is an indicator of the fact that it is genetically inherited. Most of the available literature on families suggests that there are greater chances for an individual to be diagnosed with schizophrenia if the person already has someone diagnosed with this disorder in the family (Gottesman, 1978). According to Gottman (1978) if the prevalence of schizophrenia in the general population is 1% then there are 12% chance of schizophrenia in first-degree relatives, and if both parents are having schizophrenia then the chances will exceed 40% for the child. But still, it is debatable whether schizophrenia in families is due to nature or due to nurture as all of them is sharing the same environment.
Twin and Adoption Studies
Twins and adoption studies have also shown evidence that schizophrenia tends to run in families rather than have an influence on the environment. According to Heston (1970) if a monozygotic has developed schizophrenia then there are 90% chances that the other twin will develop some sort of mental illness. But again, recent findings have suggested that the environment strengthens the effect of genetics. So, still, there is a need to explain the biological causes of schizophrenia to better understand it.
Brain Structure
The latest Imaging technologies CAT and MRI have contributed a lot in explaining the brain structure in relevance to schizophrenia. According to Weinberger (1978), schizophrenic persons have enlarged cerebral ventricles. The size of the cerebral ventricle is non specifically responsible for cerebral dysfunction. With the advent of structural imaging technologies, volumetric differences have been observed in schizophrenics as compared to non-schizophrenics. According to some laboratory findings, decreased volume of the superior temporal gyrus has been observed during the episodes of illness. Furthermore, a reduction of size in the medial temporal cortex including the hippocampal cortex has also been observed. Although the size reduction has accounted for 5% of the population it has consistently over the research.
Brain Function
Researchers have observed brain dysfunctioning due to reduced neural activity in prefrontal regions with an impact of negative symptoms in the inferior parietal and prefrontal
cortex (Heckers, et al.,1999, p. 1118). Studies have provided evidence about the increase in the functioning of basal ganglia along with changes in delimited cerebral areas, and the decrease in the regional cerebral blood flow (rCBF) and metabolism in the middle frontal and anterior cingulate gyrus. But the conflicting findings were observed in the case of rCBF as some findings suggest no alteration in the schizophrenics when compared with normal subjects. Whereas, another study conducted on the auditory recognition task, has shown that normal populations and schizophrenics differ only in ACC/medial frontal cortex.
Dopamine Hypothesis
Evidence shows that drugs that are known to increase dopamine which is an agonist; cause an increase in schizophrenic symptoms; whereas when drugs that antagonists known to decrease the dopamine are given to patients, this decreases the symptoms of schizophrenia. Based on these observations, it has been theorized that an overactive secretion of dopamine causes schizophrenia as when antipsychotic drugs are given to patients with schizophrenia, it reduces their psychotic symptoms by blocking dopamine receptors in the brain.
Neural System
Long tract pathways were observed by DeLong (1990, p. 283) between subcortical and frontal cortex areas through which the functioning of the frontal cortex was influenced by the thalamus and basal ganglia. Basal ganglia contain a wide variety of modulators and neurotransmitters that are richly innervated by the structure of the brain, so if any alteration occurs in the basal ganglia then this could change the frontal cortical function via these long tract pathways (Nolen-Hoeksema & Rector, 2015, p. 766).
Neuro-developmental factors
Evidence has been provided that the neural networks subserving schizophrenia mature after late teens that produce symptoms of schizophrenia. Although not much work has been observed in this case scenario, still this framework is important.
Prenatal and Perinatal Influences
Evidence has suggested that the prenatal and perinatal environment is somehow involved in the development of schizophrenia. When a fetus is exposed to any infection, virus, pregnancy, or delivery complications these environmental conditions influence the child to later on developing schizophrenia. The use of Marijuana by pregnant mothers is also seemed to be a cause of later-on schizophrenia (Nolen-Hoeksema & Rector, 2015, p. 766).
Conclusion
The given report provides evidence of cognitive and biological explanations of schizophrenia. It is inferred that there is no definite cause of schizophrenia that has been diagnosed until now but there is evidence that genes interact with the environment to produce and strengthen the symptoms of schizophrenia. Furthermore, no single school of thought is enough to explain this disorder rather an integrated approach is required that explains the probable causes of schizophrenia.
References
Walker, E., Kestler, L., Bollini, A., and Hochman, K. M. 2004. “Schizophrenia: Etiology and Course. Annual Review of Psychology”, 55(1), 401–430.
Comer, R.J. and Whitford, F.W., 1996. “Fundamentals of abnormal psychology”. New York: WH Freeman.
Nolen-Hoeksema, S. and Rector, N.A., 2015. “Abnormal psychology”. Boston: McGraw-Hill.
American Psychiatric Association. 2007. What is Schizophrenia. Retreived from https://www.psychiatry.org/patients-families/schizophrenia/what-is-schizophrenia
