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Biological Approach - Coggle Diagram

- - - - Aim: Investigate the genetic and environmental factors within major depression disorder and gender
      - 15,493 of twin pairs participated in the experiment
      - Conducted a trained telephone interview and assessed their lifetime MDD by the DSM - IV citeria
      - 8056 individuals were diagnosed with MDD whilst 322 twins discussed anti-depressant treatment
      - MZ twins are more susceptible to depression if one of them gets . No correlation of number of years that the twins lived together and depression - provides evidence that depression is inherited
  - - - Selective placement could affect the results as babies tend to be adopted by families with similar backgrounds to the biological parents.
      - The adoptive children are not representative of all children --> low generalisability.
      - The act of bing given up for adoption may affect the child's behaviour
- - - - Metapotrobic neurotransmitter:
      - Excitatory neurotransmitter: Increases the likelihood that neurons firing an action potential
      - Agonist: Dugs that binds to the receptor
      - Inhibitory neurotransmitter: Decreases the likelihood that neurons firing an action potential
      - Antagonist: Drugs that block the receptor site and don't allow the neurotransmitter to do its job.
      - Examples
        
        Acetylcholine: Consolidates memory in hippocampus
        
        Dopamine: Controls the brain's rewards & pleasure centres.
        
        Norepinephrine: Arousal & alertness
        
        Serotonin: Sleep, arousal & emotions
  - - - Sample: 20 healthy males, with an average age of 28 years old
      - The participants were put into 2 groups: Group 1: injected with scopolamine 70 - 90 minutes before the experiment.
        Group 2: placebo (controlled group)
      - Participants took an fMRI brain scan while playing the “Arena task” - virtual reality game in which the researchers are observing how well the participants are able to create spatial memories. The goal is for the participants to navigate around an “arena” to reach a pole. After learning where the pole is located, the screen would go blank for 30 seconds. During this time, the participants were told to actively rehearse how to get to the pole. When the screen reappears, they are in a new arena and have to work their way back to the pole.
      - The brain activities of the participants were measured for six trials. The participants redid the test after 3 or 4 weeks. *receiving the opposite treatment to the original study. → a repeated measures design
- - - - used a transgenic mouse where the gene that regulates the production of monoamine oxidase A (MAOA), an enzyme that breaks down serotonin and norepinephrine, was ‘knocked out” or deleted.
      - Between days 11 and 16, the transgenic mice showed several signs of low MAOA, including frantic running, violent shaking during sleep and a tendency to bite the experimenter. In adult males, they observed signs of offensive aggressive behaviour - including bite wounds.
      - a mouse was introduced into the cage of another mouse. With control mice, when the "intruder" was introduced, the mice would "check out" the other mouse, sniffing and engaging with the mouse. In the transgenic mice, the mice adopted a threatening hunched position and would engage in aggressive behaviour. This was also true in the case where the intruder was a female mouse.
      - Autopsies of the brains of the mice showed an increase in serotonin, dopamine, and norepinephrine. Although dopamine was not highly elevated, serotonin levels were six to nine times higher than the control mice.
      - MAOA deficient mice exhibited strong aggressive behaviour. The researchers concluded that when human males lack MAOA and demonstrate aggressive behaviour, the behaviour cannot be attributed to social factors. Instead, the MAOA deficiency is a predisposition toward aggressive behaviour which may be expressed through interaction with social and environmental factors.
- - - - Estrogen: Produced in the ovaries - sexual and reproductive development in women
      - Testosterone: Produced in testes & correlates with aggression
        
        Zak et al (2009) carried out a study to test the role of testosterone on aggression.
        
        The sample was made up of 25 male students.
        
        First, the researchers drew blood from the participants to establish baseline levels of testosterone. They then had the participants rub a gel on their shoulders. The participants were randomly allocated to one of two conditions: a prescription testosterone gel or a placebo. The men returned the next morning another blood test was done to record the actual increase in levels of testosterone in the participants. The treatment had doubled the amount of testosterone in the experimental condition.
        
        Then the participants were asked to play the Ultimatum Game. Each participant in the game was told that he could be generous to another player with money he controlled - or he could be stingy. Stingy offers could be rejected by the other person. Rejected offers caused both men to lose all the money on the virtual table.
        
        The study was a double-blind counter-balanced repeated measures design. The men returned four weeks later and repeated the procedure but this time got the other substance to rub on their shoulders.
        
        The participants were 27% stingier when they had received the testosterone gel than when the received the placebo.
      - Adrenaline: Activates the Sympathetic Nervous System (SNS)
      - Insulin: Produced in beta cells and allows the cells in the muscles, fat and liver to absorb glucose that is in the blood.
      - Cortisol: Produced in the adrenal glands & increases the amount of glucose in the blood - provides energy for "fight or flight" response