Biological explaintions of phobias

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  • Biological Approach to phobias
    • Presumptions
      • 1. That our ancestors would feared certain stimuli (e.g. snakes) which promoted survival passed there genes on to us, thus making us more prone to fear similar stimuli
        • 2. Some of us are born with a innate tendency to be more physiological aroused, which makes us very sensitive to our environment and thus more prone to develop a phobia
          • 3. That anxiety is caused by a disruption in biochemistry and abnormal brain activity.
    • Family Studies
      • The aim of these studies are to atempt to establish a link between phobic disorder and genes. This is done by looking a concordance rates of phobic disorder in first degree and second degree relatives, and comparing with a control.
        • Solyom - studied 47 phobic disorders and found that 45% of patients had a family history of psychiatric disorder and 30% of their mothers had a phobia. In the non phobic control group it was only 19%.
        • Noyes - found a higher then normal rate of agoraphobia (11.6%) and panic disorder (17%) between first degree relative. This data was acquired using the family interview method, which was used to report the symptoms of these phobias.
        • Fyer - found that 31% of patients with a  phobia had a relative which also diagnosed with a phobia, but only 2 out of the 49 patients had a relative with the same phobia.
    • Twin studies
      • These studies also aim to establish a genetic link. psychologist look a pairs Mz (100% shared DNA) and Dz (50%) and look at concordance rate of phobias.
        • Torgersen - found a condance rate of 31% in Mz twins for panic disorder and agoraphobia. He found a 0% concordance with Dz twins. (note none of the Mz twins shared the same phobia)
        • Kindler - interview 722 female twin pairs with a history of phobic disorder. He found lower concordance rates in Mz twins then Dz twins. Kindler suggests the close protective bond Mz twins share can explain the lower rates. He also found environment was a more sensible explanation for the development of specific phobias
        • Kindler - studied over 2000 female twin pairs, he found that if one had a social phobia in 24% of the cases the other did to for Mz. for Dz twins it was 15%.
    • Role of GABA
      • GABA is a neurotransmitter that is released when brain activity is abnormally high (under stress). It has a calming effect on the brain. The gene DR D2 has an inhibiting effect on the release of GABA and thus and contribute to someone developing a phobia.
        • Evidence can be found from studies of people treated with Bzs. These drugs work like GABA by binding to receptors and decreasing arousal. It has been shown in these studies that Bz reduce arousal.

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