BIOLOGICAL EXPLANATIONS AO1 + AO3

Question 1

Genetic explanation

Answer 1

• suggests individuals are predisposed and have a genetic vulnerability to SZ , due to their genes. This may explain why patients often have other family members with schizophrenia.
• In order to determine whether schizophrenia has a genetic link Gottessman conducted a very large-scale family study, and concluded that if both parents suffer from schizophrenia, then there is a 46% chance of the
  child also developing the disorder (compared to a 1% chance for the general population)- therefore
  showing there’s a genetic link for developing SZ.
• SZ is thought to be polygenic meaning development is influenced by multiple genes SZ appears to be aetiologically heterogeneous, so different combinations of factors can lead to SZ.

Question 2

Dopamine hypothesis (DH)

Answer 2

• which claims that excessive amounts of dopamine or an oversensitivity of the brain to dopamine is the cause of schizophrenia.
• It states that messages from neurons that transmit dopamine fire too easily or too often, leading to symptoms of schizophrenia.
• Schizophrenics are thought to have abnormally high numbers of D2 receptors on receiving neurons, resulting in more dopamine
  binding and therefore more neurons firing.
• Neurons are important in regulating attention. If it is disturbed then it may lead to problems with attention , perception and thoughts- these are all characteristics of schizophrenia

Question 3

Neural correlates

Answer 3

• refers to the measurements of the structure/function of the brain that can correlate with an experience. For instance, the positive and negative symptoms have neural correlates.
• Avolition (a negative symptom) involves loss of motivation. Motivation involves anticipation of a reward. (using the ventral striatum region of the brain).
• This leads to the development of avolition. Research to support this was conducted by Juckel et al (2006) measured activity levels of ventral striatum in schizophrenia and found lower levels of activity than in controls. Suggesting that part of the brain is a neural correlate of negative symptoms of schizophrenia.

Question 4

One strength of biological explanations is that there is supporting research from family studies.

Answer 4

• For example, Gottesman concluded that the greater the degree of genetic relatedness, the greater the risk of developing schizophrenia.
• This shows that genes do play an important factor in the development of schizophrenia.
• However, if genes were the only cause of schizophrenia then the concordance rate would be 100%.
• Also, the theory is biologically deterministic as the predisposition by genes doesn’t mean we will
  definitely get the disorder. And, many researchers now accept that schizophrenia concordance rate in
  families may be more to do with common rearing patterns or other environmental factors rather than heredity

Question 5

A strength of biological explanations is that there is supporting research from twin studies.

Answer 5

• For example, twin studies help researchers work out whether nature or nurture has a greater influence.
• Gottesman and Shields found that the concordance rate for schizophrenia in monozygotic (MZ) twins is 48% compared to 17% for dizygotic (DZ) twins, and found schizophrenia is inherited through genes.
• Furthermore, Joseph (2004) showed concordance rates are 40.9% for MZ twins and 7.9 for DZ twins. This suggests that there is a strong genetic component to the development of schizophrenia.
• This is an advantage as findings are further supported due to this retest, and therefore increasing reliability of the supporting research.
• However, the sample sizes of twin studies is small so it is difficult to generalise to the wider population.
• Therefore, limited usefulness

Question 6

One strength of the DH is that there is supporting research.

Answer 6

• For example, research has shown thatdrugs that increase levels of dopamine (for example, amphetamines) produce psychotic (schizophrenic symptoms).
• This shows that increased levels of dopamine activity lead to schizophrenia symptoms.
• This is an advantage as it demonstrates the key principles of the DH which increase the validity of the theory.
• However, Clozapine is the most effective drug at reducing schizophrenic symptoms. It acts on serotonin as well as dopamine which implies that serotonin is involved in schizophrenia– it is not just dopamine.
• This suggests that the dopamine hypothesis is limited and does not explain all factors that lead to SZ