symptoms of schizophrenia

Positive symptoms

  • Hallucinations - Hearing and seeing things that are not there, may have controlling voices telling them what to do
  • Delusions - False beliefs e.g your movements are being controlled
  • Disordered thinking - Thought insertion - Thinking that someone has put thoughts into your mind and thought broadcasting - Thinking that everyone can hear what you are thinking

Negative symptoms

  • Flatness of emotion
  • Lack of energy
  • Social withdrawal
  • Reduced energy

Features of schizophrenia -Affects 1% of population. Genetically linked. No gender differences in prevelence. Male onset 18, female onset 25 

25% of schizophrenic patients have enlarged ventricles in the brain

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Brain structure in SZ

Schizophrenics are suggested to have smaller brainds, and enlarged ventricles, which are fluid filled sacs in the brain.

The neurodevelopmental hypothesis suggests that SZ is due to abnormal brain development, which is latent in the individual and triggered by brain maturation in early adulthood

Post moterm analysis of patients with SZ have shown abnormalities, the most consistant being enlarged ventricles, which implies a loss of brain cells.

The pre-frontal cortex may also have effects, as studies have shown reduced metabolic rates in the prefrontal cortex of SZ patients

Research using CAT scans have shown approx. 25% of SZ patients have enlarged ventricles - which are normally caused by the death of brain tissue surrounding the ventricles, and fluid expanding to fill the space

This is not unique to SZ, patients with parkinsons show similiar structural damages to the brain

According to the ND hypothesis, various factors during the womb, the birth procedure or after birth can cause brain lesions and make the individual vulnerable to SZ

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Evaluation of the brain structure hypothesis

There is alot of research demonstrating that there is an association with enlarged ventricles, for example studies of post mortem analysis showing englarged ventricles in the brains of SZ patients, and also studies using CAT scans showing similar results

Much of the supporting research comes from brain scan techniques, making it highly scientific as it is an objective measure to look at specific sizes of the brain or ventricles, so that differences can be found

There are alternatvie explanations such as neurotransmitter imbalance, which looks at the effect of excess dopamine and lack of gluatamate in causing SZ, there are also non- bio explanations such as social causation

It has applicability value in the sense that causes of a disorder often lead to a relevent treatment, but this may be difficult because it is difficult to change brain structure, but drug treatments made

There are mixed results found though, the extent to which ventricles are englarged is modest in most patients and many do not display it at all

Causation cannot be inferred as data is correleational, the brain dsyfunctions may be an effect 

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The dopamine hypothesis

Dopamine is an NT, its receptors can be present in the brain in different numbers

It is thought that in SZ sufferes there is a hypersensititivity in the D2 receptors leading to over assocaition and therefore positive symptoms, this is associated with hallucinations and paranoia

Research has found this increased number in receptors may only account for around a 6% increase in that from a normal brain. 

Research has shown that dopamine may not be the only NT implicated in the development of SZ. The glutamate hypothesis expands upon the dopamine one

PCP is a drug which blocks the glutamate receptors, and increases dopamine, the use of this drug is associated with psychotic like state including changes in cognitive function

Animal research showed that the drugs led to a lack of glutamate, but not always a increase in dpoamine, but still led to psychosis like symptoms, suggesting glutmate must play some role

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Evaluation of the NT hypothesis

Figee et al found enhanced activity in the prefrontal cortex of SZ's, supporing the hypothesisi

Alot of research has also come from the fact that antipsychotic medicines work by inhibiting dopamine, suggesting it must play some effect

Alot of this research comes from brain scans, which increases the scientific value of the theory

Alothough drug treatments block dopamine receptors, not all patients repond. PET scans show that blocking dopamine receptors does not always remove the symptoms, in around 10%

There is an alternative thory from social psychology - which is social learning theory, a supporting study for this explanation is bandura 

This explanation can sucessfully explain the exsistance of positive and negative symptoms

It is hard to establish a cause and effect relationship

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social causation hypothesis

People in the lowest social class/ group have a higher incidence of SZ in the UK

People in lower social class groups are also more likely to be brought for medical help by police or social services or be compulsary admitted

Social adversity - SZ is more associated with living in cities than in rural areas, e.g freeman found higher incidences in chicago and london, these areas are more densly populated

Pressues in childhood (social adveristy) link to being lower class, features that may be important is unemployement and poverity, social isolation, and seperation from parents

Immigrant populations - census data in the UK have consistantly shown a higher incidence (4 times)  of SZ in the afro-carribean and black immigrant population

This is not thought to be caused by genetics, because it only occurs in the UK population

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Evaluation of social causation hypothesis

There is supporting research evidence from hollingshead and redlich who found that there were higher incidences of SZ in those of lower socio-economic groups

Social drift hypothesis provides an alternative explanation, the theory suggests that people who get SZ move down in social class and area due to the negative stigma surrounding it, they were not there to start with.

This explanation does not account for biological factors such as the dopamine hyptothesis, which suggests that excess levels of dopamine cause positive symptoms in SZ's

As this explanation highlights the importance of enviromental factors, it would suggest that ACT is a useful treatment as it focuses on care in the community

There problem may actually be with diagnosis, those in lower socio- economic groups, living alone and in poverty are more likely to get a diagnosis because they are flagged up as someone with higher risk

There are other risk factors too, in urban areas crowded living conditions can lead to toxins in the envirroment, lack of social support and instablility in communities can lead to social isolation

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