stats and studies schizophrenia

Andreason

3 signs of avolition:

• poor hygiene and grooming

• Lack of persistence in work/education

• lack of energy

Cheniaux et al

2 psychologists independently diagnose 100 patients using ICD and DSM

Using DSM- 39 diagnosed

Using ICD- 68

(Lack concurrent validity- can lead to inaccurate diagnosis)

Psychiatrist one- DSM:26 ICD:44

Psychiatrist two- DSM:13 ICD:24

Low inter-rater reliability- no consistency

Cheniaux- ICD diagnosis

68

Cheniaux DSM diagnosis

39

Cheniaux psychiatrist one

26 DSM, 44 ICD

Cheniaux psychiatrist 2

13 DSM 24 ICD

Jakobson et al

• tested the reliability of the ICD-10 classification system for the diagnosis of schizophrenia

• Found high inter rater reliability of 98% when 100 Danish patients were diagnosed by different clinicians

• Suggests high inter rater reliability of clinical diagnosis of schizophrenia using up-to-date classifications

Read

People diagnosed with schizophrenia have sufficient symptoms of other disorders that they could receive at least one other diagnosis

Buckley et al

• Around 50% of people with a diagnosis of schizophrenia also have a diagnosis of depression

• 47% substance abuse

Cochrane

• Incidence of schizophrenia in the West Indies and the UK is similar, around 1%, but in the UK people with African or Caribbean heritage are 7x more likely to be diagnosed with schizophrenia

• Suggests higher diagnosis rates are not due to genetic vulnerability but cultural bias

Gara et al

African American men with severe depression tend to be misdiagnosed with schizophrenia in comparison to other racial groups

Suggests that clinicians put more emphasis on psychotic rather than depressive symptoms in African American men which shifts the diagnosis towards schizophrenia even when these patients show similar depressive and manic symptoms as white patients

Broverman et al

Clinicians in the UK equated mentally healthy adult behaviour with mentally healthy male behaviour, illustrating a form of androcentrism

As a result there was a tendency for women to be perceived as less mentally healthy when they do not show male behaviour

Loring and Powell

• Randomly selected 290 males and females

• Psychiatrists to read case studies of ‘patient’ behaviour and make a judgement using standardised diagnostic criteria

• Patients were either described as being male/ gender was not stated or female

• Male psychiatrist:

  • Male/no gender- 56% given Sz diagnosis

  • Female- 20%

• Female psychiatrist-no gender bias found

• Diagnosis is influenced by gender of patient and of clinician

Gottesmann

• large scale family study- found a link between degree of genetic similarity and shared risk of schizophrenia

• Dz twins- 17%

• Mz twins- 48%

• General population- 1%

• Suggests genes play a crucial role and provide good evidence for understanding the influence that genes play BUT not 100% - other factors

Joseph

• Mz Twins treated more similarly than Dz twins

• encounter more similar environments,

• Experience more identity confusion (eg. Treated as the twins)

Ripke et al

• Study combining all previous data from genome wide studies

• Up to 108 different genetic variations are associated with an increased risk of schizophrenia

• Genes associated with increased risk: those in the brain and tissues with a role in immunity, those coding for the functioning of several neurotransmitters, including dopamine

• Supports biological causation

Kety and Ingraham

• Prevalence rates of schizophrenia were 10x higher among genetic relatives than adoptive relatives- suggesting genetics play a greater role than environment

• Role of environment eliminated by looking at individuals who grew up away from their biological parents

Curren et al

When amphetamines (which activate dopamine production-agonists) are given to non-sufferers it can produce schizophrenia-like symptoms and make symptoms worse in those already suffering from schizophrenia

As amphetamines increase the dopamine activity this suggests that excess dopamine activity may lead to schizophrenia

Kessler et al

Used PET and MRI scans to compare people with schizophrenia with non-sufferers

finding that schizophrenics have elevated dopamine receptor levels in certain brain areas (such as the mesolimbic pathway, which is linked to positive symptoms) and differences in the levels of dopamine in the cortexes can be found

Supports dopamine hypothesis

Lloyd

If dopamine is a causative factor in schizophrenia, it may be an indirect factor mediated through environmental factors, because abnormal family circumstances can lead to high levels of dopamine, which in turn trigger schizophrenic symptoms

Torrey

• ventricles of a person with schizophrenia are about 15% bigger than normal

• Enlarged ventricles lead to negative symptoms

Tomoyuki

• 10year longitudinal study

• 15 experimental and 12 controls (matched pair design- age, gender, education duration)

• Used brain scanning techniques

• Progressive ventricle enlargements in experimental group but not control

• Enlarging linked to worsening of negative symptoms, such as speech poverty= correlational evidence

Allen et al

• Scanned the brains of patients experiencing auditory hallucinations and compared them to a control group whilst they identified pre-recorded speech as their own or others

• Lower activation levels in the superior temporal gyrus and anterior cingulate gyrus found in the hallucination group who also made more errors

• Reduced activity in those 2 areas of the brain is a neural correlate of auditory hallucinations and issues with speech comprehension

Tilo et al

Used MRI scans to investigate the level of activity in the Wernicke’s brain area (an area associated with coherent speech) when schizophrenic and non-schizophrenic patients were asked to talk about a Rorschach ink-blot

In schizophrenic patients the severity of their thought disorder was negatively correlated with the level of activity in the Wernicke’s area

(I.e. low activity in Wernicke’s area related to severe speech disorganisation/incoherence)

Ho et al

• Performed 3 MRI scans on resent-onset-schizophrenics and recanted them 3 years later

• Found evidence of brain damage in the recent-onset patients which worsened over time, especially in the frontal lobes, which correlated with an increase in the severity of symptoms

• Suggest brain damage does increase in schizophrenics over time and may not be the initial cause of the disorder

Vaughn and Leff

• relapse rates higher among patients who had been discharged into home environments with higher expressed emotion

• High EE- 51% and Low EE-13%

• In high EE families likelihood of relapse correlates with amount of time spent with families

Tienari et al

• children taken from schizophrenic mothers and adopted into healthy or dysfunctional families

• Adopted into healthy families- 5.8% prevalence

• Adopted into dysfunctional families- 36.8%

• Supports family dysfunction theory and also interactionism

Stirling

• Compared 30 patients with schizophrenia and 18 non-patients on the Stroop Test, participants had to name the ink colours of colour words, which involves suppressing the impulse to say the word

• Sufferers took over twice as long to name the ink colours

• They found it harder to suppress their automatic response (saying the word) while performing deliberate actions (saying the ink colour)

• Supports central control dysfunction

Tarrier et al

• CBTp has a significant effect in reducing positive and negative symptoms of schizophrenia

• Reviewed 20 trials of CBT using 739 patients.

• Consistent evident that it reduces persistent positive symptoms in chronic patients and may have modest effects in increasing recovery speed in acutely ill patients

Thornley

Reviewed studies that compared the effects of chlorpromazine (typical antipsychotic) with a control group where patients received a placebo.

Data from 13 trials and 1121 patients

Chlorpromazine associated with with better overall functioning, reduced symptom serving, lower relapse rates

Melzer

Clozapine (atypical antipsychotic) is more effective than typical antipsychotics as well as other atypical antipsychotics

Effective in 30-50% of treatment resistant cases where other treatments have failed

Pharoah et al

Moderate evidence to suggest that family therapy significantly reduces hospital readmission over the course of a year and improves quality of life for patients and their families

NICE review of family therapy

Demonstrated that when family therapy was used in combination with other treatments such as drug therapy it was associated with significant cost savings

Because the extra cost of family therapy is offset by a reduction in cost through preventing the need for further and long lasting treatments (drug therapy reduces symptoms + family therapy creates a more supportive family environment = reduces relapse rates)

Tarrier et al combination treatments

CBT and antipsychotics = effective treatment for schizophrenia and more effective than drugs or CBT alone

Drug therapy can reduce the symptoms of schizophrenia and CBTp can help the patient to challenge their irrational beliefs and understand their hallucinations and delusions as well as reduce their symptoms

McMonagle and Sultana

Small study found token economy improved negative symptoms over 3 months when used in psychiatric hospitals

Partially supports token economies as a way of reducing symptoms and managing schizophrenia