Intro: Alzheimers disease (AD)
- Most common type of dementia (loss of mental ability - gradual death of brain cells).
- AD patients have certain type of cell - β-amyloid protein 42 which builds up.
- Generally the link between β-amyloid protein 42 deposits & cognitive problems is rather weak which does make it difficult to see how plaques can be the cause of AD.
- The 2nd change in the brains of AD patients is "tangles" which occur in dead cells - formed from a build up of tau protein which arise when the structure of the neuron cell body degenerates.
- Down syndrome is a type of mental retardation caused by having an additional copy of chromosone 21, most patients reach middle age & develop AD.
- Researchers have looked into how your life style may affect how you attract the disease, but found that you inherit it.
- Led researchers onto looking for genes associated with AD on chromonsomes 21 - other genes have been looked into.
- The main focus & role these genes play is to produce more β-amyloid protein 42 therefore explaining why some people are more prone to develop the disorder.
- Berntson et al found other areas that are also affected by AD like the hippocampi - AD affects the brain tissue which affects the memory & makes patients less alert.
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- Cummings et al - found that dogs do deposit more β-amyloid protein 42 with age , although dont produce plaque & tangles like human AD patients - research is helpful but does have drawbacks as no animal has the same symptom.
- We know from brain changes, that there's a pattern of damage to brain circuits in humans & we know from animal studies i.e rats and monkeys that these circuits are then damaged - result in memory loss.
- Although, generalising from animals to humans may not be vlaid - don't have the same brain circuits/symptoms. Only a correlation so it's not possible to infer a cause & effect relationship as cannot state that β-amyloid protein 42 is causing the cognitive dysfunctions.
- Problem is with all thse explanations - seem to suggest that AD is determined by our biology (biologically determinist) & we're unable to make free choices, as it's written in our DNA.
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Post-traumatic stress disorder (PTSD) Intro:
- May develop after a person's exposed to 1 or more traumatic event i.e. sexual assault, warfare, etc for longer than 1 month, if not known as an acute stress disorder.
- Although, if symptoms (e.g. disturbing & reoccuring flashbacks, avoidance) continue for longer than 1 month, the diagnosis of PTSD will be given.
- Although can't explain how after a traumatic event, everyone reacts differently e.g. one person witnessing a fire may develop PTSD, whereas somebody else may not.
- Women are more likely to experience higher impact events & develop PTSD than men - children are less likely to experience PTSD - especially if under 10 - war veterans are more commonly at risk.
- Neurological explanation - a traumatic event causes long term alterations & abnormalities in specific brain systems - suggested that these events triggered the release of adrenaline & serotonin in order to prepare for the fight or flight response.
- Van der Kolk suggested that there's an absence of resilience in those suffering from PTSD if the arousal isn't to be prepared - reached this conclusion from lab studies on war veterans exposed to etreme stress - they demonstrated higher physiological activity (e.g. in heart rate) - concluded that trauma damages the noradrenergic system, raising levels of noradrenaline making the person more startles.
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Behavioural explanation of PTSD:
- Based on Pavlov's theory of classical conditioning - PTSD can be explained in terms of "state or situation" - anything that elicits a fearful emotional response or anything that resembles the original traumatic event can trigger stress levels.
- More recent application of the psychodynamic explanation is that the approach proposes that someone who has experiences more emotional trauma in their childhood - more vulnerble to trauma in later life.
- Kaminer & Lavie found that holocaust survivors who were demmed better adjusted to their experiences were less able to recall their dreams in REM sleep than those who were less adjusted.
- Supports the role of repression in reducing anxiety in people who suffer from PTSD - inability to recall dreams due to the fact they have a strong ego defence machanimsm - lacks internal validity & this is a consequence of demand characteristics.
- Kosten suggested that the levels of noradregeneric energy affects how susceptibe the patient is to PTSD - higher the levels, the more startled/alert the patient it.
- Found higher noradrenaline levels in PTSD hopsital patients, although doens't explain the mechanism through which noradrenaline levels are affecting memory which ignores differences between patients
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- Psychological & sociocultural factors play a very important role in the persons vulnerability to develop the disorder. However, Scott & Stradling suggested that PTSD can occur without a trauma but also through prolonged exposure to stressors.
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