Semantic memory distortions in dementia of the Alzheimer's type

The cognitive distortion seen in dementia must reflect a decline from a higher premorbid level of functioning and be severe enough to interfere with social or occupational responsibilities.Prevalence estimate for dementia increase significantly with age and approximately 6% of individuals over age 65 and 20% over age 80 suffer from a medically or socially disabling degree of dementia. As the investigation of cognitive processes associated with memory functioning continues to move forward, so will our ability to measure and characterize memory distortion at both the structural and functional level. Recognition of the existence of two dissociable memory system has led to an explosion of interest in the neurology of memory and the search for brain structures that mediate non declarative memory systems.Unfortunately, most of the researches so far have examined the nature and extent of only one or the other component of memory impairment. No attempt has been made to study the interactions among various components. DAT, by its nature is diffused and bilateral and therefore neuropsychological functioning is simultaneously affected by many types of cognitive impairment.