Schizophrenia and Diagnosis of Mental Disorders

Diagnosis

Diagnosis

The process of matching a person’s behaviour, cognitions, feelings, and desires to the signs and symptoms of a recognized mental disorder to provide information about prognosis and treatment.

Prognosis - a prediction of the course, duration, severity, and outcome of a condition, disease, or disorder.

Deviance

Behaviors, cognitions, feelings and desires which are extreme, unusual or bizarre and which differ from social and statistical norms.

Dysfunction

An inability to conduct everyday activities.

Distress

The subjective experience of feeling upset and anxious.

Danger

An individual at risk of causing physical or psychological harm to themselves or others.

Issues & Debates

Koryagin (1981) described how the Russian KGB pressurised psychiatrists in the 1960s to diagnose and incarcerate political dissidents.

Moncrieff (2010) - demonstrates how the misuse of psychiatric diagnosis can legitimise punitive punishments and social exclusion.

Reliability of the DSM-3

Spitzer (2012) and his colleagues felt that 0.7 on Cohen’s kappa would indicate ‘good agreement’.

Johnstone and Miners (2014)

Suggests psychologists are turning to ‘formulation’ as an alternative to diagnosis. This involves building up a personal story that allows the clinician to understand how past traumatic experiences have caused current distress.

Regier and colleagues (2013)

3 disorders including PTSD had kappa values ranging from 0.60-0.79 (very good) while seven more diagnoses including schizophrenia had kappa values of 0.40-0.59 (good).

Major depressive disorder (MDD) had one of the least reliable diagnoses (0.28)

Cooper (2014)

DSM-5 task force classified kappa values 0.2-0.4 as ‘acceptable’, so the fall in standards suggests DSM is less reliable than previous versions because of the risk of error during diagnoses.

Fazel et al. (2009)

Weaknesses of using the 4D’s for diagnosis:

• 4D’s create labels - media distortion can cause schizophrenic people to seem more dangerous than normal people.

Poniozovsky et al. (2006)

Strengths - Reliability of ICD:

• Compared reliability of ICD-9 and ICD-10 using PPV (positive, predictive value) which is the proportion of people getting the same diagnosis when reassessed.

Galeazzi et al. (2004)

Strengths - Reliability of ICD:

• Compared reliability of ICD-9 and ICD-10 using PPV (positive, predictive value) which is the proportion of people getting the same diagnosis when reassessed.

Mason et al. (1997)

Strengths - Validity of ICD:

• Good predictive Validity for Schizophrenia

• ICD-9 & ICD-10 were reasonably good at predicting disability in 99 people with schizophrenia 13 years later.

Luhrmann et al. (2015)

Cultural Differences in Hearing Voices:

• Interviewed 60 American, Indian & Ghanaian people with schizophrenia

• 70% of Americans - harmful, destructive voices.

• 50% of Ghanaians - mainly positive voices.

• 20% of Ghanaians - voices told them to kill or fight.

• Indian people tended to hear family members compared to only 10% of Americans.

Strengths - DSM-5 and ICD-10 are reliable because of consistent schizophrenia diagnosis

• Regier et al. (2013) - Kappa value was 0.46 in field trials of DSM-5.

• Sartorius et al. (1995) - high kappa value of 0.86.

Desbonnet (2016)

• Found overactive dopamine D2 receptors in areas like the limbic system linked to positive symptoms of schizophrenia.

• Negative & Cognitive schizophrenia symptoms can link to low functioning of dopamine D1 receptors in the PFC.

Davis et al. (1991)

Dopamine Deficiency - Hypodopaminergia

Suggests:

Excess Dopamine in the mesolimbic pathway - positive symptoms of schizophrenia

Limited Dopamine in the mesocortical pathway - negative symptoms of schizophrenia

Insel (2010)

• Suggests schizophrenia stems from abnormalities in early brain development, starting in the first few weeks of gestation.

• People who exhibit schizophrenic symptoms in their late teens & early 20s exhibit similar prodromal (pre-diagnostic symptoms).

Howes & Kapur (2009)

Dopamine Dysregulation & schizophrenic symptoms:

• Describes dopamine dysregulation in the striatum as a common pathway to psychosis.

Tenn et al. (2003)

Strengths of Neurotransmitters (biological explanation of schizophrenia):

• Research Support - Found rats given 9 amphetamine injections over 3 weeks showed various schizophrenic symptoms, which can be seen as social withdrawal.

Snyder (1985)

Strengths of Neurotransmitters (biological explanation of schizophrenia):

• Support for D2 receptors - Chlorpromazine acts as an antagonist at many D1 & D2 dopamine receptors, has an antipsychotic effect.

Dépatie & Lal (2001)

Weaknesses of Neurotransmitters (biological explanation of schizophrenia):

• Showed that apomorphine, a dopamine agonist that stimulates D2 receptors, does not include psychotic symptoms.

• This challenges how hypodominergia is responsible for positive symptoms of schizophrenia.

Veling et al. (2008)

Weaknesses of Neurotransmitters (biological explanation of schizophrenia):

Second Generation Immigrants:

• Showed Moroccan immigrants in the Netherlands were more likely to be diagnosed than Turkish Immigrants & correlated with the amount of actual & perceived discrimination faced by each group.

Hilker et al. (2018)

Schizophrenia: Genetic Influence (One other biological explanation)

• A recent estimate for the heritability of schizophrenia is 79%.

Wright (2014)

Schizophrenia: Genetic Influence (One other biological explanation)

• As many as 700 genes have been linked to schizophrenia.

Houston et al. (2008)

Schizophrenia: Genetic Influence (One other biological explanation)

Diathesis-Stress Model: Schizophrenia genes are only triggered by biological and environmental factors.

• ‘Stress’ was often seen as psychological, created by harsh parenting.

• Stress is now seen as anything that risks triggering schizophrenia.

Susser & Lin (1992)

Schizophrenia: Genetic Influence (One other biological explanation)

Epigenetics: How genes are turned on and off by environmental stressors.

• Reported that women who became pregnant during the famine had low birth weight babies who were twice as likely to develop schizophrenia.

Mil et al. (2006)

Schizophrenia: Genetic Influence (One other biological explanation)

Epigenetics:

• Found MZ twins had up to 20% greater ‘methylation’ of two genes linked with schizophrenia.

Gottesman (1991)

Strengths for Schizophrenia: Genetic Influence (One other biological explanation)

Research Support:

• Found a clear relationship between genetic similarity and an increase in two related individuals having schizophrenia.

Gottesman & Shields (1966)

Strengths for Schizophrenia: Genetic Influence (One other biological explanation)

Research Support:

• Found a concordance rate of 42% for MZ twins and 9% for DZ twins.

Dahown et al. (2017)

Strengths for Schizophrenia: Genetic Influence (One other biological explanation)

Research Evidence on DISC1 and COMT genes:

• Reviewed 14 studies and concluded that DISC1 is associated with presynaptic dopamine dysregulation, a key factor in schizophrenia.

Egan et al. (2001)

Strengths for Schizophrenia: Genetic Influence (One other biological explanation)

Research Evidence on DISC1 and COMT genes:

• Proposed a link between decreased dopamine activity in the PFC and 1 form of the COMT gene.

Tienari et al. (1994)

Issues & Debates:

Strengths for Schizophrenia: Genetic Influence (One other biological explanation)

• A 21-year longitudinal study supports the diathesis-stress model.

• Adopted children whose biological mothers were diagnosed with schizophrenia were more sensitive to family dysfunction in adoptive homes than those from low-risk backgrounds.

Pederson & Mortensen (2006)

Weaknesses for Schizophrenia: Genetic Influence (One other biological explanation)

• Research demonstrates the longer a person is exposed to urban life (dense population), the greater the risk of developing schizophrenia.