Schizophrenia is a severe mental illness affecting thoughts, feelings and behaviour through its positive and negative symptoms. Schizophrenia has been found to affect around 24 million people, approximately 0.32% of the entire population (WHO, 2022). However, this is one of the less common mental illnesses affecting the population. It is a seriously debilitating illness for some, and many people who have the illness experience discrimination and prejudice in addition to their symptoms.
The cause of schizophrenia is still unknown, but we will cover some of the theories of schizophrenia that have been proposed to explain the illness.
Schizophrenia is a severe psychological illness that may cause the individual to suffer from delusions and hallucinations, often making them develop a sense of paranoia, freepik.com/storyset.
- We will start by looking at some of the biological theories of schizophrenia, including family theories of schizophrenia and the dopamine theory of schizophrenia.
- Moving on, we will then learn about the psychological/environmental theories of schizophrenia, such as the double-bind theory of schizophrenia.
- You may notice that we will also cover the etiological theory of schizophrenia, which explains the cause of the illness as an interaction between biological and environmental components.
Biological theories of schizophrenia
The biological theories of schizophrenia propose that the illness should be explained by biological factors such as genetics, neurotransmitters disruption to specific regions of the brain, and brain abnormalities.
Family theories of schizophrenia
Family studies, such as twin studies, support the role genes play in the onset of schizophrenia. Gottesman (1991) found a 48% concordance rate of schizophrenia in monozygotic (Mz) twins and 17% in dizygotic (Dz) twins.
Mz twins share 100% of the same DNA, whereas Dz twins share 50% of the same DNA.
Gottesman's research suggests that genetics make up a significant component of schizophrenia. However, it cannot solely explain its onset. If this were the case, we would expect to find a 100% concordance rate between Mz twins.
Concordance rate is the likelihood that two people will share a characteristic, in this case, the gene for schizophrenia.
The dopamine theory of schizophrenia
Schizophrenia is characterised by two types of symptoms: positive and negative. The dopamine theory of schizophrenia proposes two different reasonings for the cause of both types of symptoms.
Dopamine is an example of a neurotransmitter responsible for transmitting chemical messages from neuron to neuron. Neurotransmitters can have excitatory effects, in which they increase activity in the brain, or inhibitory effects, which decrease activity in the brain.
Excessive dopamine may be the cause or related to the symptoms of schizophrenia. The dopamine hypothesis was proposed after observing that amphetamine, a drug that increases dopamine levels, increased psychotic symptoms and reserpine, a drug that decreases dopamine levels, reduced psychotic symptoms.
Antipsychotic drugs were created to treat other mental illnesses.
Since its origins, the dopamine hypothesis has developed to include further dopamine systems within the body, not just the neurotransmitter itself. The symptoms of schizophrenia are now believed to be linked to irregular dopamine receptors in specific brain regions. There are four dopamine pathways in the brain; two of which have been associated with the symptoms of schizophrenia:
- The mesolimbic pathway is also known as the rewards system. Hyperactivity of dopamine in this pathway is associated with positive schizophrenia symptoms.
- The mesocortical pathway is responsible for affective emotions. Dysregulation of dopamine in this pathway is associated with negative schizophrenia symptoms.
The mesocortical and mesolimbic pathways are the two dopamine pathways that have been linked with schizophrenia, freepik.com/hilch.
Brain structures related to schizophrenia
The brain structures that have been associated with schizophrenia are:
- The frontal lobe is responsible for working memory, voluntary movement, speech, language and executive functions such as coordination.
- The temporal lobe is involved in language, visual perception and affective emotions. The hippocampus, a structure within the temporal lobe, has also been associated with schizophrenia. The hippocampus is responsible for memory consolidation and learning.
Turetsky et al. (1995) used an MRI and identified that patients with schizophrenia had significantly lower brain volume in the left temporal and right frontal lobes. The results indicate that the structural differences may explain the symptoms of schizophrenia. Research has also noted a significantly lower hippocampal volume in patients with the illness.
Heckers et al. (1998) identified that patients with schizophrenia had decreased activity in the hippocampus and increased activity in prefrontal regions of the brain when carrying out memory retrieval tasks. Other research has also shown hyperfrontal activity; this can explain why schizophrenia patients have difficulties with memory and attention (Soyka et al., 2005).
The findings suggest that patients with schizophrenia have increased activity in the frontal lobe and decreased activity in the temporal lobe, which may explain the symptoms of schizophrenia.
We have just discussed the cortical damages related to schizophrenia. However, there is also evidence of a link between neurological damage and the illness, too.
Inflammation in the brain and dopamine/serotonin neurotransmitter and receptor dysfunction has been linked with the onset of schizophrenia.
Evaluation of the biological theories of schizophrenia
A common and effective treatment for schizophrenia used is typical and atypical antipsychotic medications. These drugs target dopamine receptors and affect how much of the neurotransmitter is released into the synapse. Typical antipsychotic medication reduces the presence of the positive symptoms of schizophrenia.
The effectiveness of the treatment suggests that an abundance of dopamine is related to schizophrenia.
However, the biological theories of schizophrenia take the side of nature in the nature-nurture debate. The theory ignores the importance of nurture, such as our environment or social pressures; thus, the theory can be considered reductionist. The biological approach is reductionist as it over-simplifies a complex illness to biological components and ignores other important components of the nurture stance of the debate.
Psychological theories of schizophrenia
Now that we have learned about the biological factors that contribute to schizophrenia let's move on to look at theories of schizophrenia that propose psychological factors cause the illness.
The double bind theory of schizophrenia
Bateson et al. (1956) proposed the double bind theory. The theory suggests that children whose parents give contradictory messages are more likely to develop schizophrenia. According to Bateson, the double-bind theory proposes situations wherein children "cannot win" no matter what they do.
Critical and over-bearing parents may tell their children that they are this way because they care for them and wish to protect them; this is a contradictory message.
The conflicting messages and pressure from parents cause internal conflict in children which Bateson proposed leads to the onset of schizophrenia.
According to the psychological theories of schizophrenia, the illness is caused by environmental factors, freepik.com/studio4rt.
The social drift theory of schizophrenia
The social drift theory of schizophrenia proposes that the symptoms of schizophrenia cause people with the illness to maintain or shift to a lower social class. It focuses on the maintenance rather than the onset of schizophrenia.
According to the theory, society rejects people with schizophrenia because they assume the individual to be "crazy or unstable". The individual is marginalised, and people may try to avoid the individual. The avoidance behaviour can lead to the disengagement of the individual. The person with schizophrenia may give up on themself because they believe and accept the opinions of society.
Accepting the view leads the individual to acknowledge the label and act accordingly, leading to the maintenance of a lower social class. People of lower socioeconomic status have less financial stability and fewer opportunities to receive support for their mental health issues.
The social drift theory of schizophrenia explains the maintenance and not the onset of schizophrenia.
Evaluation of the psychological theories of schizophrenia
Family therapy is another common intervention provided to schizophrenia patients. The intervention aims to improve communication and relations between the patient and their family. In essence, this is similar to trying to counterattack what the double-bind theory proposes as the cause of schizophrenia.
The double-bind theory is widely criticised and is no longer a common explanation for the illness as it appears to blame parents for a serious mental illness.
The social drift theory is useful because, unlike other theories, it attempts to understand the long-term effects and potential causes for the maintenance of schizophrenia by addressing society. However, it is difficult to establish the cause and effect of the variables proposed by the theory.
Did schizophrenia cause the low social class, or did the low social class cause schizophrenia. Stress has been linked to schizophrenia, and people of lower socioeconomic status may have more stress.
Etiological theory of schizophrenia
The etiological theory of schizophrenia considers all potential causes of schizophrenia and the development of the disorder. Both the biological and psychological theories of schizophrenia can be considered reductionist. The etiological theory considers how genetics and environmental factors interact and lead to the onset of schizophrenia, and is a diathesis-stress model.
According to the theory, schizophrenia is caused by a genetic vulnerability triggered when an individual can no longer handle pressure from the environment.
An example of the etiological theory of schizophrenia is the biopsychosocial model of schizophrenia.
Theories of Schizophrenia - Key takeaways
- Schizophrenia is a severely debilitating illness affecting less than 1% of the population (WHO, 2022).
- Biological theories of schizophrenia, such as genetics, the dopamine theory of schizophrenia and structural and functional differences, have been proposed to explain the onset of schizophrenia.
- The double bind theory of schizophrenia is a psychological theory that has been put forward to explain the onset, whereas the social drift theory explains the maintenance of schizophrenia.
- Both psychological and biological theories of schizophrenia can be considered reductionists, so the diathesis-stress model may be the most inclusive explanation for the disorder.
References
- WHO. (2022). Schizophrenia.
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