Psychology- Depression

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Clinical Characteristics

Clinical Characteristics of Depression:

  • sleep disturbances 
  • change in appetite
  • weight gain or loss
  • sadness and despair
  • change in mood
  • loss of interest in usual activities
  • lethargic or hyper-active
  • difficulty concentrating
  • negative self-concept
  • recurrent thoughts of death or suicide

At least 5 of these symptoms must be present for a period longer than 2 weeks. They cannot be present due to bereavement.

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Issues of Classification

Reliability is how far the classification system produces the same diagnosis.

Validity is whether the classification system is actually measuring what it aims to measure. 

Subjective- the characteristics are subjective as they may not be the same for everyone

Implications- teach people to be wary of their symptoms e.g. seek medical advice is two or more a present. Schools can help; if the notice symptoms they can talk to the pupil

Other Behaviour- some people may have other characteristics but they may be due to environmental factors e.g. lethargic because of lack of iron

Not Scientific- depression cannot be measured and may be different for everyone

Comorbidity- if someone has another illness they may be more likely to become depressed e.g. if they have a terminal illness

Diathesis Stress- going through a stressful time in their life may cause someone to show depressed symptoms.

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Issues of Classification


Inter-Rater Reliability- different doctors should reach the same diagnosis on the same person

Test-Retest Reliability- test should produce the same results for the same person on two occasions.

Gender Bias- more common in women so diagnostic bias may be present

Cultural Differences- may be differences in symptom presentation throughout cultures

Labelling- labelling someone with depression has negative effects with employment, motivation

Bias Diagnosis- local GP bases diagnosis on previous patient knowledge so may be biased

SAD- seasonal affected disorder may affect diagnosis

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Explanations of Depression

Biological Explanations


  • first degree relative means higher chance than others (Kendler)
  • twin studies show 46% concordance MZ and 20% DZ (McGuffin)
  • adoption studies found higher incidence of depression in biological relatives in depressed group (Wendler)


  • gene starves brain of serotonin 
  • 10 times more likely to have depression than those without gene (Zhang et al)

Neurotransmitter Dysfunction:

  • deficiency of the neurotransmitter noradrenaline
  • low levels = depression (Bunny et al)
  • diet with low tryptophan (increase serotonin) had low mood (Delgado et al)
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Explanations of Depression

Biological Explanations Continued

Cortisol Hypersecretion:

  • elevated levels of stress hormone cortisol in depressed individuals 
  • overactivity in HPA system
  • levels return to normal when depression disappears
  • elevated cortisol reduces brain serotonin = depressive state
  • Dexamethasone drug that supresses cortisol secretion in normal people
  • in depressed people it does not maintain cortisol suppression for long = overactive HPA
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Explanations of Depression

Biological Explanations- Evaluation

Strickland- no evidence of increased cortisol in depressed women

All Behaviour- twins could be imitating each other. not 100% concordance rate so must be other factors. not everyone with a twin/ family member gets depression. does not account for free will. still some people who get depression but not due to biology.

Scientific- can measure serotonin, cortisol, noradrenaline levels. difficult to establish cause and effect relationship between biology and environment. 

Implications- if you know you may be biologically at risk you can try to avoid getting it. gene therapy, manipulating the genes to avoid getting depression. can educate the importance of knowing family history etc.

Other Explanations- diathesis stress, could be due to biology but brought on by other factors. parsimonious as it ignores environmental influences. cognitive and psychological explanations.

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Explanations of Depression

Psychological Explanations- Cognitive

Beck suggested depression was due to negative thinking. Negative schemas could be a result of rejection and criticisms in childhood which results in thinking the worst of situations. 

Beck's Cognitive Triad:

  • personalisation- when they feel to blame for everything
  • view of self- i don't deserve to be in college
  • view of world- my class thinks I'm stupid
  • view of future- I won't pass this class

Beck suggests 3 Common Cognitive Biases:

  • arbitrary influence (jumps to conclusions using wrong information)
  • over generalisation (make vast sweeping statements based on small events) 
  • magnification/ minimisation (mountain molehill/ under emphasis on positive event)
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Explanations of Depression

Psychological Explanations- Cognitive Behavioural

Abramson suggested learned helplessness results after a failure to control a situation. They fail to initiate coping strategies during stress.

They hold themselves responsible for unpleasant events. They think the cause is:

  • Internal- it is their fault
  • Stable- likely to continue into the future
  • Global- everything they do is wrong
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Explanations of Depression

Psychological Explanations- Behavioural

Lewisohn suggests a lack of positive reinforcement leads to social withdrawal.

He proposed depression arises from reinforcement because:

  • the individual never enters into social situations
  • the individuals behaviour in social situations does not elicit a rewarded response from other people
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