Literature Review on Schizophrenia

Running head: LITERATURE REVIEW ON SCHIZOPHRENIA
LITERATURE REVIEW ON SCHIZOPHRENIA
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1LITERATURE REVIEW ON SCHIZOPHRENIA
Introduction
Schizophrenia is chronic and a cognitive disorder that is characterised by hallucinations,
delusions , thought disorders, avolition, poor expression of the emotions, social withdrawal,
suicidal tendency and other cognitive difficulties that significantly affects the way a person
behaves and believes. It usually appears in the early adulthood or the late adolescent period.
There are generally five types of schizophrenia- paranoid schizophrenia, disorganized, or
hebephrenic schizophrenia, catatonic schizophrenia, childhood schizophrenia and schizoaffective
disorder. In Australia, Schizophrenia affects about 1.5 % of the population. The prevalence of the
disease is more in the migrants than the native born people (Australian government, Department
of health, 2018). 15 % of the people suffering from schizophrenia have had suicidal ideation
frequently (Australian government, Department of health, 2018). Furthermore, there is also a
strong public perception about schizophrenia, that all the schizophrenic patients are violent and
can pose harm to the society.
The most effective available treatment for the schizophrenia involves both medication
and psychological therapy yet there had been recurrent symptoms of schizophrenic episodes. In
order to incorporate appropriate treatment strategies, it is necessary to have an in depth
understanding of the biological, psychological and the social factors responsible for the
symptoms. This literature review aims to explore the above mentioned factors behind the
etiology of the disease.

2LITERATURE REVIEW ON SCHIZOPHRENIA
Biological factors
Brain structure discoveries in case of Schizophreniua have been noticed with the help of
magnetic resonance imaging (MRI). Volumetric differences in the brain of the schizophrenic
patients have been observed. The volume of the superior temporal gyrus has been noticed in
Schizophrenia and a correlation can be found between the changes in the volume and the
characteristics of the illness (Rees et al., 2016). The medial temporal cortex, including the
entorhinal, hippocampal cortex, parahippocampal and the hippocampal cortex have also shown
reduction in size and the results has been consistent across different laboratories. Karlsgodt et al.,
(2010), have noted that there is a reduced blood flow in the prefrontal cortex in the brain in
schizophrenia and this information served a great deal to develop the future ideas. Recently, the
laboratories have focused on the abnormalities on the anterior cingulated cortex and the
hippocampus of a schizophrenic brain. It is known that a normal brain involves a complexly
interacting neuronal system. There is a long tract pathway between the sub cortical are and the
frontal cortex, through which the basal ganglia affects the functioning of the frontal cortex (Rees
et al., 2016). Since basal ganglia involve a diversity of modulators and neurotransmitters, any
abnormality in the neurotransmitter functioning in the basal ganglia might lead to schizoaffective
disorder. Furthermore, a study examined brain surface contraction in the schizophrenic patients
(Sun et al., 2009). Surface contraction in the prefrontal and a reduction in the grey matter have
been found to be higher in patients than the control group. Apart from the neurological factor,
there are several genetic variants that make substantial contributions to thee this disorder.
A direct observation of the environmental and the genetic factors was demonstrated when
it was observed that fetal hypoxia can be associated with the reduction in the grey matter and
increased cerebrospinal fluid in patients suffering from Schizophrenia. Other free-natal factors

3LITERATURE REVIEW ON SCHIZOPHRENIA
associated with schizophrenic disorders are low folate, which can lead to the an increased plasma
homocysteine (Rees et al., 2016) . An increased homocystiene imparts a modulatory effect on N-
methyl- D-aspartate (NMDA) receptor, the key component of the gluitamatergic theory of
schizophrenia.
Psychological factors
Certain environmental triggers and discrete events can trigger schizophrenia. Stresses like
loss of parents, partners, disrupted family patterns, rejection, criticism, over involvement, high
anxiety and conflicts at home or with partners might lead to extreme stresses.
Factors like social isolation and high expressed emotions are one of the main cause of
Schizophrenia. Expressed emotions have been found to be a significant predictor of the relapse
of schizophrenia. However, there are very few papers in precipitating the first break in the
psychosis. Jiang et al., (2013), had studied the impact of the environment of the family in the in
the development of schizophrenia and found that lower levels of caregivers emotional
attachment, warmth and remarks is associated with disruptive behavioral pattern in children. A
study conducted by Li et al., (2017), have proved that social isolation leads to a series of
schizophrenic deficit problems such as social withdrawal, cognitive impairment, anxiety
disorder, sensorimotor gating disturbances, Surprisingly, Social isolation has also been linked
with the potential interactions between histidine triad nucleotide binding protein 1 (HINT1), the
NRI subunit of N-methyl-d-aspartate acid receptor, and D2R (dopamine type 2 receptor)
(Mumtaz, Khan, Zubair & Dehpour, 2018). Similarly, a study by Jiang et al., (2013), has
reported that deletion of the N-methyl-D-aspartate receptor (NMDAR) from a subset of
corticolimbic interneurons present in the mouse brain at the time of early postnatal development