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Schizophrenia: Key explanations

Get to know the key theories by reading our summaries and selection of essays

Clinical Characteristics and Diagnosis

In order to be diagnosed with schizophrenia a psychiatrist will use a diagnostic manual to assess the number of criteria met by the person. According to the DSM-IV, two or more of these key symptoms must be experienced fairly consistently over a 1 month period by the individual. The most important defining symptom that must be present for diagnosis is the experience of hallucinations.

o Hallucinations

o Delusions

o Disorganised speech

o Very disorganised behaviour (inappropriate emotional responses/bizarre purposeless actions) or catatonic behaviour (inflexibility in body movements or over flexibility)

o Negative symptoms (lack of emotions, speech or motivation)

Sufferers are also likely to experience a decline in one or more social or occupational areas of functioning e.g. work, relationships or inability to care for oneself. This must be a factor that has deteriorated since the onset of the disorder and not have existed beforehand. A diagnosis also requires these disruptions in behaviour to have existed for a period of at least 6 months, including the month of consistent symptoms discussed previously.

Genetic Explanation

This approach to explaining the cause of schizophrenia focuses on the hereditary nature of the disorder, with a large amount of research to support this claim. The disorder has been shown to have a strong genetic basis and individuals with a parent who has suffered from schizophrenia are more at risk of developing schizophrenia themselves, compared to those who do not have close relatives with the disorder. This risk is higher than the naturally occurring rate of 1% in the general population. However, it is very difficult to determine the strength of genetics and the role of the environment in the development of the disorder because a child whose parent has schizophrenia will share their genetic make-up but will also share the same environment as their parent. Thus, for this explanation to be supported psychologists must investigate using twin studies and adoption studies, that aim to separate the effects of genetics from other contributory factors.

Neurochemical Explanation

This explanation of schizophrenia focuses on the levels of important neurotransmitters in the brain, specifically dopamine, and thus is referred to as the dopamine hypothesis. For example, when dopamine levels are increased by taking recreational drugs such as LSD (lysergic acid diethalymide) or amphetamines, it can result in symptoms relatable to schizophrenia e.g. hallucinations, delusions and disruptions of motor activity.

The over-production of this neurotransmitter impacts on certain areas of the brain where there are large numbers of dopamine-containing neurons. These areas of the brain (the basal ganglia and the frontal cortex) are involved in the regulation of motor activity. In people who suffer from Parkinson’s disease a degeneration of dopamine neurons in these brain areas can lead to significant loss of control over their movements. When these individuals are treated with a drug that increases dopamine (L-Dopa), often they will experience symptoms similar to schizophrenia. Therefore, offering further support for the role of dopamine in schizophrenia.

Cognitive Explanation

There are two key cognitive theories that explain schizophrenia. The first is referred to as the Attention Deficit Theory and was proposed by Frith (1979). He argues that the attention system in people with schizophrenia is not working effectively and this causes individuals to experience an overload of information from their senses. They are unable to filter out information from their preconscious (thoughts we are unaware of) and thus become overwhelmed with the amount of information that is entering their conscious awareness. A non-sufferer would ordinarily be able to filter out thoughts or information that are irrelevant and only attend to the necessary information in conscious awareness. When this defective system is coupled with an inability to focus, people with schizophrenia will exhibit signs of disordered thinking. Frith argues this is the cause of positive symptoms such as delusions and hallucinations.

The second explanation focuses on how people with schizophrenia process information. It appears that they give subconscious priority to stimuli in their surroundings that could be regarded as threatening. This information is attended to and processed more vigorously than other less emotional or threatening events. This is referred to as attentional bias and could again offer an explanation for the positive symptoms seen in people suffering from schizophrenia. For example, paranoid delusions may be the result of increased attentional bias towards an object e.g. a knife and misinterpretation of the event as a possible threat to the person.

Psychodynamic Explanation

According to this approach the cause of schizophrenia lies in the overuse of defence mechanisms, particularly regression. Regression is used as a form of protection for the Ego, the part of the personality concerned with understanding the rules and expectations of society. It is characterised by reverting back to an earlier stage in childhood, usually the “oral stage”. This can be seen in some adult’s behaviour when they revert to using childish methods of comforting themselves when under great stress (e.g. thumb sucking). When a child experiences a home life that is not nurturing their ego development is weak and they begin to overuse defence mechanisms to cope with this hostile environment. Overuse of regression in turn causes the Ego to break down and leaves the Id as the dominant personality component. The Id is the part of the personality we have as a newborn baby and could be described as the selfish part, seeking immediate gratification for our basic, instinctual wants and needs. When the Id is in charge it can lead to primary narcissism (extreme self-focus).

This process can relate directly to the development of schizophrenia as the individual becomes so self-absorbed, that they cannot comprehend the feelings or needs of others, and could be the cause of symptoms such as withdrawal from society. This persistent focus on themselves leads them to lose touch with reality. Hallucinations might be the result of these individuals trying to engage with real life again but being unable to separate their unconscious desires from what is actually real.