IB Psychology HL - Abnormal - Analyse Etiologies of Depression

• scientifiƒc study of„ causes/origins of„ disorders or abnormal behaviour

• important because of the idea that treatment should be related to the cause of„ the disorder (i.e. if the disorder is caused by biological factors, a biomedical approach to treatment should be used)

• evolutionary theory (Hagen et al., 2004)

• genetic predisposition (Kendler et al., 2006)

• serotonin hypothesis (Coppen, 1967)

• cortisol hypothesis

Hagen et al. (2004):

• depression signals need/attention

• to elicit help from members of the group

• however, like all evolutionary theories this is impossible to test experimentally

Kendler et al. (2006):

• massive twin study on 42000 participants

• found that concordance rates among monozygotic twins of 44% for female and 31% for male, while dizygotic twins exhibited 16% for female and 11% for male

• if the disorder were purely genetic, we might expect the monozygotic concordance rates to be much higher

• but the difference between monozygotic and dizygotic concordance rates is enough to indicate a strong genetic component

• some evidence for genetic predisposition (Kendler et al., 2006)

• but depression is a complex disorder

• environmental factors (e.g. stress) also play an important role

Main idea: depression is caused by low serotonin levels (Coppen, 1967)
- supported by the effectiveness of the drug Prozac, which improves mood by inhibiting serotonin reuptake

• short alleles of the 5-HTT gene also inhibits serotonin reuptake like Prozac, but its carriers are more likely to suffer depression
  NOTE: Levinson (2005) argues that the 5-HTT gene simply makes individuals more sensitive to stressful life events, and doesn’t necessarily cause depression

Sarek (2006): tianeptine, a drug used in Europe and South America to treat depression, enhances serotonin reuptake…

Lacasse and Leo (2005):

• lack of evidence that low serotonin causes depression

• the effectiveness of a treatment doesn’t imply a causal effect (e.g. aspirin alleviates headaches, but headaches are not caused by a lack of aspirin)

• some evidence that serotonin may be involved in depression (effect of Prozac)

• but research doesn’t show a clear link between serotonin and depression

• see how short allele of 5-HTT gene and Prozac generally has same biological effect but opposite physiological effect

• there may be a confounding variable we are unaware of

• the stress hormone cortisol may play a role in the development of depression

• particularly high cortisol levels appears to have damaging effects on a developing brain

• Burke et al (2005): cortisol activity differs between depressed and non-depressed – non-depressed’s cortisol levels rise and fall rapidly during and after stressful situations, but depressed’s cortisol levels remain high for longer after stressful situations

• Cutuli et al. (2010): significant correlation between high levels of cortisol and a history of negative life events

• lots of evidence of physiological correlations to mental state

• but we don’t have a clear understanding of how depression might develop biologically

• still need to research more about interactions between stressful life events, genes, hormones, and neurotransmitters

Beck (1976):

• depression is caused by a cluster of negative thoughts in 3 categories: the self, the world, and the future

• these thoughts form a vicious cycle of negative automatic thoughts

• the triad is perpetuated by cognitive biases like over-generalization (about negative aspects, e.g. “I never do well in tests”), polar reasoning (i.e. does not take any ambiguities), and selective abstraction (i.e. only focusing on the negatives)

• contradicts traditional depression theories: negative thinking is typically considered to be a symptom of depression, not the cause

cognitive triad in action: self (“I’m not good at anything”) → world (“Everyone hates me because I’m worthless”) → future (“I’ll never be good at anything because everyone hates me”) → repeat

Strengths:

• descriptively very powerful

• Robins and Block (1989): depressed people have negative thinking styles

• Lewinshohn et al. (2001): negative thinking and high stress levels often preceded the onset of depression

• Boury et al. (2001): there is a significant correlation between amount o„f negative automatic thoughts and the severity of„ depression (BUT they also note that correlation =! causation)

• treatment: Beck’s cognitive triad resulted in the creation of CBT (cognitive-behavioural therapy)

Weaknesses:

• Boury et al. (2001): correlation =! causation

• no explanations: unclear whether this model reflects cause of depression or simply disordered thinking

• Taylor and Brown (1988): depressed people interpret events more realistically

• unemployment/poverty (Brown and Harris, 1978)

• social inequality

• individualist vs collectivist

Brown and Harris (1978):

• interviewed 450 London women

• unemployed single mothers who lacked social support were most likely to undergo depression

• thus Brown and Harris identified 3 vulnerability factors: unemployment/poverty, lack of social support, and social responsibilities (e.g. children to take care of)

• received much support on vulnerability factors

• but it can be argued that the factors are unlikely to be responsible for creating feelings of sadness, only propagating it

• Cohen (2002): historically, rates of depression are higher when social inequalities are deeper

• possibly due to feelings of powerlessness and worthlessness that are exacerbated by physical conditions (e.g. stress, malnourishment)

• may also be a product of socialization within individualist, materialist cultures; comparing to higher socioeconomic groups leads to perceptions of inequality, unfairness and inability to participate in ‘ideal’ society

• Wu and Anthony (2000): lower prevalence of depression in Hispanic communities, possibly because levels of social support are higher

• Gabilondo et al. (2010): depression occurs less frequently in Spain than in other European countries, possibly because of strong traditional roles of family and religiousness

• Chiao and Blizinsky (2010): depression was associated with individualism, but strangely the short 5-HTT allele was more common in collectivist countries – perhaps collectivist cultural norms (e.g. increased social support) was developed to protect more biologically vulnerable groups