2. Biochemical explanation of mental illness

Question 1

Biochemical: Dopamine hypothesis

1. What does biochemical refer to?
2. What does the biochemical explanation examine?
3. What are neurotransmitters?
4. How do neurotransmitters communicate?
5. General Link to mental illness

Answer 1

1. Biochemical refers to chemical processes within the human body that affects behaviour, emotions and thinking.
2. Biochemical explanation; Examines the role of neurotransmitters as a cause of the symptoms of some mental health disorders.
3. Neurotransmitters are chemicals that are produced in the brain and allow neurons to pass electrical messages to one another eg. dopamine
4. Neurotransmitters are released from one neuron across the synaptic cleft and bind to the synapse receptor.
   Receptors only bind to the specific chemical released from the first neuron. For example, dopamine will only bind to dopamine receptors.
5. Mental illness can result from too many or too few neurotransmitters binding to receptors.

Question 2

Dopamine hypothesis of Schizophrenia. (5 points)

Answer 2

• SZ caused by high levels of dopamine.
• Dopamine – excitatory neurotransmitter; enhances feelings of arousal, reward and motivation.
• Decreased levels of D1 receptors in the prefrontal cortex causes a lack of energy and motivation which links to NEGATIVE symptoms of SZ.
• Increased levels of D2 receptors in the Ventral Striatum and these Link to POSITIVE SYMPTOMS of SZ for example hallucinations and delusions.

Question 3

Evidence for the Dopamine Hypothesis (2)

Answer 3

• Drugs such as amphetamine and cocaine increase levels of dopamine in the brain and can cause symptoms which resemble those present in psychosis.
• antipsychotics such as fluphenazine, have been found to block D2 dopamine binding receptors and reduce positive psychotic symptoms.

Question 4

Scientific (2)

Answer 4

• The methods take a scientific approach as they use objective scientific equipment to measure dopamine such as PET scans, postmortems (counting the D2 receptors in the brain).
• Use of experiments shows cause and effect e.g. injecting Schizophrenics with dopamine enhancing drugs causes more positive symptoms.

Question 5

Deterministic(1)

Answer 5

The explanation is deterministic as it suggests that high levels of dopamine activity cause positive symptoms. Dopamine levels are out of control of the person soyou cannot havefree will over dopamine levels

Question 6

Reductionist- S&W (2)

Answer 6

This is a reductionist explanation as it is a very simplistic explanation of schizophrenia as it only looks at one factor. Dopamine.

+ Focusing on one cause led to the development of anti-psychotic treatments

• Focusing on onefactor only means that other causes arebeingignorede.g.Other neurotransmitters such as serotonin, environmental factors etc

Question 7

Usefulness - S (2)

Answer 7

• There are practical applications to the dopamine hypothesis; if positive symptoms are due to increased activity in the D2 receptors in the striatum this can be used to develop treatments.
• Drugs such as clozapine have decreased symptoms by reducing dopamine activity in the D2 receptors.

Question 8

Nature/Nurture(2)

Answer 8

• Recent research suggests that schizophrenics have genetic abnormalities relating to the dopamine system supporting the nature argument. Over production of dopamine in the striatum or oversensitivity to dopamine.
• The dopamine hypothesis supports the role of nurture as recent research suggests that schizophrenia can be affected by events that happen in our environment after birth

Question 9

Outline how the biochemical explanation can be used to explain mental illness [5] A01 (model answer)

Answer 9

The biochemical model can be used to explain mental illness and in particular Sz. Sz is a psychotic disorder characterised in the DSM 5 as a severe disruption in psychological functioning with a loss of contact with reality.

One way it can explain this is through the chemical imbalance of neurotransmitters. Neurotransmitters are chemicals that are produced in the brain and allow neurons to pass electrical messages to one another, people with mental illnesses (SZ) appear to have an imbalance of these when compared to non-sz’s.

In particular when explaining sz there seems to be an imbalance of a neurotransmitter called dopamine. Dopamine is an excitatory neurotransmitter that is associated with arousal, rewards and motivation. Dopamine is passed from one neuron to the other by receptors found in the post-synapse of neurons. There are 5 types of dopamine receptors in the brain and research has suggested that for those who experience positive symptoms such as hallucinations and delusions have higher levels of D2 receptors in their ventral striatum. On the other hand there has been a link between low levels of D1 receptors in the pre-frontal cortex and negative symptoms such as lack of energy or movement (avolition).

The role of drugs has also added to the strength of this argument. When given amphetamines people increase their chances of experiencing sz symptoms such as delusions and hallucinations. Furthermore Parkinson’s suffers have been found to have low levels of dopamine in their brains. When given L-Dopa (drug that increases dopamine) it has been found to create sz symptoms in some patients if not controlled.
Drugs such as fluphenazine have been found to reduce the symptoms of sz in many suffers. Fluphenazine works by binding to the receptors on the post-synaptic neuron to prevent them from allowing excessive dopamine from entering the system