Etiology of Schizophrenia

Schizophrenia: EtiologyE. KENT ROGERS

Physiological

Almost all mental health workers now agree that the cause of schizophrenia has a strong biological element. There is a robust and growing body of evidence that supports this. In the next few slides, we’ll be looking at these:

1. Stem cell research

2. Specific gene abnormalities Brain structure abnormalities

3. Protein abnormalities found in the blood of schizophrenia.

4. Family patterns, including identical twin studies

5. Successful treatment with medication

6. Neurotransmitter abnormalities

7. Brain anatomy abnormalities

8. Brain wiring abnormalities

9. In utero Virus

Stem Cell Research

Stem cells taken from schizophrenics and trained to become neurons produce more dopamine than that of controls (Vivian Hook, 2014)Argument for Biological Cause: Since stem cells

have not had any social or other experiences, the problem must be based in genes.

Counter-argument: EpigeneticsCounter-Counter-Argument: Regardless of how

genes came to be as they are, they are still the cause

Abnormal Genes Identified

Gene ZNF804a implicated schizophrenia Girgenti, et al. (2012)

Hovatta et al. located likely genes associated with schizophrenita (1999)

(Just write: “Girgenti et al. and Hovatta et al. and others have found genetic abnormalityes associated with schizophrenia”

Counter-argument: Can’t be genes alone since identical twins (monozygotic twins) only have a fifty percent chance of both having schizophrenia

Protein Blood Screenings

These blood tests check protein levels and types. Schizophrenics have differences from normal population. These screenings are over 80% accurate in diagnosing schizophrenia. (Bahn et al.)

Argument: A biological abnormality suggests biological cause.

Counter-argument: Experience and behavior is known to alter how biology functions

Family Patterns

The closer the relationship, the more likely both members are to have schizophrenia. (See textbook for specifics).

Argument: This suggests genetic causes.

Counter-argument: If genes were alone responsible, monozygotic twins of schizophrenics would have a 100% chance of developing schizophrenia, not 50%, the actual rate. Also, being married to a schizophrenic slightly increases the chance of a partner having it. This points to social influence, which also occurs in families.

Medications In 1951, phenothiazines were developed by Lobrorit. They reduced

psychotic symptoms.

These same drugs caused muscle tremors as seen in Parkinson’s disease.

It was known that Parkinson’s is caused by low levels of dopamine in some areas of the brain. Therefore, perhaps the antipsychotics were lowering dopamine which would mean high levels of dopamine might cause the symptoms of schizophrenia.

And too much L-dopa, the medicine that treats Parkinson’s, causes schizophrenia-like psychosis.

Also, amphetamines greatly amplify dopamine and too much of these also cause schizophrenia-like psychosis.

Medications continued.

Therefore, it is clear that too much dopamine in certain areas of the brain cause symptoms of schizophrenia. This supports a biological etiology.

Counter-argument…same as above.

*NOTE: it should be noted that new “atypical” antipsychotics often work better than the phenothiazines. These new drugs work on other neurotransmitters, so dopamine doesn’t seem to be the ONLY factor in schizophrenic psychosis.

Neurotransmitter Abnormalities

Supporting the stem cell research and the deductions based on effective medicate, certain areas of schizophrenic brains have shown to have elevated levels of dopamine.

Brain Anatomy

Schizophrenics also have smaller brains Schizophrenics also have less grey matter Schizophrenic brains have enlarged ventricles, the spaces of fluid

in the brain. This means there is less brain mass surrounding the ventricles.

In other words, there is actual brain damage. Finally, schizophrenic brains have higher density of dopamine

receptors.

Brain Wiring/Functioning

fMRI scans have shown schizophrenic brains to function in different ways.

In Utero Viral Infections

It has been shown that children of mothers who had influenza during the second trimester have elevated risk of having schizophrenia

Evidence for Environmental Causes

As stated above, the fact that identical twins only have a 50% chance of having schizophrenia if their twin has it shows that there must be something more than genetics alone. There must be an environmental factor.

It is generally believed to be stress.

Cognitive View continued: FRITH (1992)

FRITH (1992) argued that a number of schizophrenic symptoms can be explained by deficits in Theory of Mind, a two step processes involved in empathy:

1. Inference: Recognizing how someone is feeling by non-verbal cues

2. Attribution: Understanding why someone is feeling the way they do.

Cognitive: FRITH

Firth did a test involving a story and cartoons, similar to Nelson. Each story involved a person being deceptive.

Patients and controls were then asked questions that required an understanding of what the characters were thinking and feeling.

Those with negative symptoms and paranoid delusions did worse than controls with Theory of Mind questions.

FRITH CONTINUED

Frith argued that lack of Theory of Mind accounts for the following schizophrenic symptoms:

Delusions: They can’t understand that their own ideas are not necessarily true.

Paranoia: They can’t interpret other’s intentions and when others don’t agree with their own experiences (hallucinations) they become paranoid that others are plotting.

Break down of social relationships: without theory of mind, communicating become confusing and so they withdraw.

Uniting the Biological and Environmental TheoriesThe Diathesis-Stress Hypothesis Most mental health theorists, scientists and

practitioners believe in the diathesis-stress hypothesis.

Genetic factors load the gun with the bullet. Stress pulls the trigger. If there is not enough stress, the bullet is not released (i.e., schizophrenia does not occur)

So we might think of it this way (though this is not for sure)…

Genetic abnormality PLUS STRESS leads to…

Altered protein synthesis and altered neurotransmitter, especially dopamine, levels. This leads to…

Deterioration of brain functioning and this probably leads to…

Hallucinations and break down in theory of mind which leads to…

Delusions, paranoia and social withdrawal. Which leads to

Furthers psychosis and dysfunction of the brain. This in turn leads to…

Diminished brain size, grey matter etc.