Schizophrenia: Biological explanations: Genes Implications in the real world: Applications - Schizophrenia

What will I need to know? Be able to describe two biological explanations of schizophrenia (AO1) Be able to evaluate both of these explanations (AO3) Be able to apply these explanations to a novel scenario (AO2)

Basic Neuroanatomy We are going to have a brief tour of the brain. Before we start, what parts of the brain can you remember? www.finr.net/files/brain/index.htm You absolutely need to spend some time on this site exploring the brain.

Neuroanatomy Cerebellum: “Little brain” Responsible for motor control Brain stem: regulates automatic processes, and connects brain to body Cerebrum (cerebral cortex) main part of brain

Neuroanatomy Cortex: thick top layer of brain. Made up of a thin layer of neurons 2-4mm thick folded many times to give a huge surface area. Separated into two hemispheres, and each of these into four lobes. Can you name the four lobes from memory?

Neuroanatomy Using this picture colour in the four lobes on your handout

Neuroanatomy Each lobe has a number of functions E.g occipital lobe responsible for vision Temporal lobe responsible for language Have a look at Anatomy and functional areas of the brain for more detail.

Neuroanatomy Under the cortex are many subcortical regions E.g: Limbic system (including hypothalamus, amygdala hippocampus) vital for emotion and memory Corpus callosum which connects the two hemispheres

Neuroanatomy Ventricles Filled with cerebrospinal fluid Provide brain with nutrients and remove waste Maintain brain pressure

Neuroanatomy Before we learn about what research has found about the brains of schizophrenics, what parts of the brain might you expect to be implicated in schizophrenia and why? Refer back to the handout on the characteristics of the illness to help you. The sheet Anatomy and functional areas of the brain may also be useful.

Structural abnormalities in the brain and schizophrenia Early psychology saw schizophrenia as a psychological illness However, once drugs were used to treat it, it became clear that the illness was at least partly biological Studies have suggested that schizophrenics have structural differences in their brains.

Structural abnormalities in the brain and schizophrenia Cause and effect: Do structural differences cause schizophrenia? Does schizophrenia cause structural differences? Maybe it is a combination? Before examining the evidence, which of these do you think is the most likely? Why?

Neurodegenerative or Neurodevelopmental? Is schizophrenia neurodevelopmental? Parts of the brain do not develop properly Could be genes, events in childhood etc. Changes in brain cause schizophrenia Is schizophrenia neurodegenerative? Few brain changes at start of illness Progressive worsening over time Schizophrenia causes changes in brain.

Brain ventricles Schizophrenics often have larger brain ventricles than non schizophrenics. Weinberger et al (1979) used CAT scans to compare schizophrenics with controls. Summarise his findings.

Brain ventricles An additional finding was that it did not matter how long they had suffered schizophrenia for, nor was it related to the type of medication they were taking. Look back to the information about ventricles on the first page. What might enlarged ventricles suggest? Brain ventricles enlarge when brain damage occurs. When neurons are destroyed, the ventricles enlarge to maintain the pressure in the brain Maybe in schizophrenics, brain damage has occurred.

Cortical Atrophy What differences can you see between these two images? Non-Schizophrenic Schizophrenic

Cortical atrophy What does the term cortical atrophy mean? What are the two ways that it can occur? What did Vita et al (1988) do and find?

Cortical atrophy Schizophrenic brains suffer from a loss of volume. Might mean that there are fewer neurons (brain cells). However, could be a reduction in the connections between these neurons (as argued by Feinberg ,1982). As well as neurons, the brain also contains support cells called glial cells. Reduction in brain volume may be due to the reduction of these glial cells rather than neurons.

Cortical atrophy How might cortical atrophy explain the increased ventricle size? If the brains of schizophrenics have lost volume (either fewer cells, or fewer connections between those cells) the ventricles would have to enlarge to maintain brain pressure.

Reversed Cerebral Asymmetry Our brains are not symmetrical The temporal, parietal and occipital lobes are usually larger on the left side of the brain The frontal lobe is usually larger on the right Many parts of the left hemisphere have more folds than the right. More folds mean more surface are, so the left hemisphere seems to have more cortical space than the right hemisphere.

Reversed Cerebral Asymmetry

Reversed Cerebral Asymmetry In schizophrenics, the right hemisphere is often larger than the left As language function is located on the left, this reversed asymmetry may account for some of the symptoms of schizophrenia such as alogia. What did Luchins et al (1979) do and find?

Brain changes and schizophrenia How do these brain changes cause the symptoms of schizophrenia? Structural differences do not just affect one area of the brain; the differences tend to be global and multiple areas of the brain seem to be affected. Schizophrenia is clearly a complex and variable disorder

Brain changes and schizophrenia Three groups. Take one each of the studies at the top of page 5 (Jibiki, Andeasen and Goghari) Summarise this study and it’s findings using a stick man diagram. No more than 10 words (not including the name of the study) Include a diagram to show the specific part of the brain

Neurodegenerative or neurodevelopmental? To answer this question we need to look at the results of longitudinal studies What are these studies? Oblai et al (2011) conducted a meta-analysis of longitudinal studies of schizophrenics. They found that the illness showed a clear progression with brain volume decreasing over time. Suggesting?

Neurodegenerative or neurodevelopmental? We could compare chronic schizophrenics with people at high risk. Chan et al (2011) found that those at high risk for schizophrenia had smaller brain volume and enlarged ventricles, even before showing any symptoms of psychosis. Those with chronic schizophrenia also showed this, but also had further damage to parts of the brain, for example, a smaller hippocampus. Suggesting?

Neurodegenerative or neurodevelopmental? Do the studies above suggest that schizophrenia is neurodegenerative or neurodevelopmental? Explain why. Oblai seems to suggest neurodegenerative (as brain volume decreases over time) Chan suggests neurodevelopmental (as changes are present before the illness starts) but also neurodegenerative (as chronic schizophrenics show additional changes)

Evaluation of theory Findings are reliable and replicable But not present in all schizophrenics Other factors can affect the changes Structural changes also present in many other disorders, not just schizophrenia Structural abnormalities may be due to the antipsychotic medication that many schizophrenics take

Evaluation of theory Cause and effect still unclear If the structural abnormalities caused the schizophrenia, what caused these abnormalities in the first place? If the structural abnormalities were caused by the schizophrenia, then where did the schizophrenia come from? Also, how exactly does the schizophrenia cause these changes to occur? This theory alone can not explain why the illness seems to run in families

Evaluation of theory As technology advances, we are able to examine the brains of schizophrenics more easily. One day we might be able to use brain scans to diagnose Brain scans also highly scientific.

Eval of biological theories Lots of evidence that schizophrenia is biological, particularly as it runs in families. Also responds well to biological treatments . But be careful of the treatment-aetiology fallacy!

Eval of biological theories But they are reductionist! Ignore social and cultural factors

Eval of biological theories Useful for developing treatments But highly nomothetic. Sees a person as a list of symptoms.

Eval of biological theories Highly deterministic: no room for free will However, this may be the case. Schizophrenics will often have no control over their behaviour and symptoms. Insisting that a schizophrenic has free will may actually be detrimental to their recovery.

Exam practice Answer the two exam style questions Make sure that you read the guidance first!