Explanations for disorders of memory:


One disorder of memory is Alzheimer’s disease (AD). This is the most common type of dementia (which is a loss of mental ability- and is the gradual death of brain cells). AD patients have a certain type of cell called the β-amyloid protein 42 which builds up and causes communication problems. Generally the link between β-amyloid deposits and cognitive problems is rather weak which does make it difficult to see how plaques can be the cause of AD.

                The second change in the brains of AD patients is tangles which occur in dead cells. They are formed from a build-up of tau protein which arise when the structure of the neurons cell body degenerates.  Down’s syndrome is a type of mental retardation cause by having an additional copy of chromosome 21. Some researchers have looked into how your life style may affect how you attract the disease but also if you inherit it, for example if it’s already in your genes. Most Down syndrome patients reach middle age and start to develop AD. This led researchers onto looking for genes associated with AD on chromosomes 1. Other genes for early-onset and later-onset AD have been looked into. The main focus and role these genes play is to produce more β-amyloid therefore explaining why some people are more prone to develop the disorder. Berntson et al (2002) found other areas that are also affected by AD like the hippocampus. AD affects the brain tissue which affects the memory and makes patients less alert.

                Cummings et al (1996) found that dogs do deposit more β-amyloid with age although they do not produce plaque and tangles like human AD patients develop. This research although helpful in some aspects, does have its drawbacks as no animal has the same symptom as an AD human patient. We know from brain changes that there is a particular pattern of damage to brain circuits and we know from animal studies (looking into rats and monkeys) that these circuits are when damaged do also result in memory loss. Although, generalising from animals to humans may not be valid as they do not have the same brain circuits/symptoms of human AD patients. Also, this is only a correlation so it is not possible to infer a cause and


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