Memory Loss in Alzheimer's Disease
Alzheimer's disease (AD) is a progressive neurodegenerative disease marked by a constellation of cognitive disturbances, the earliest and most prominent being impaired episodic memory. Episodic memory refers to the memory system that allows an individual to consciously retrieve a previously experienced item or episode of life. Many recent studies have focused on characterizing how AD pathology impacts particular aspects of episodic memory and underlying mental and neural processes. This review summarizes the findings of those studies and discusses the effects of current and promising treatments for AD on episodic memory. The goal of this review is to raise awareness of the strides that cognitive neuroscientists have made in understanding intact and dysfunctional memory. Knowledge of the specific memorial processes that are impaired in AD may be of great value to basic scientists developing novel therapies and to clinical researchers assessing the efficacy of those therapies.
Alzheimer's disease (AD) is a progressive neurodegenerative disease that accounts for more than two-thirds of all cases of dementia. The most important risk factor for AD is age, followed by an APOE4 genotype. A 2007 report released by the Alzheimer's Association estimated that more than 5 million Americans are currently diagnosed with AD, while a Delphi consensus study projected that the global prevalence of AD will quadruple by the year 2040 to over 80 million cases in total. Just as this disease is often devastating at the individual and family levels, the high prevalence of AD means that it is also economically and societally burdensome. Indeed, AD represented the third most costly health condition in the USA in 2000, and is of growing financial relevance for health policy planning in other industrialized and developing nations. Perhaps due to mounting evidence regarding the gravity of the situation, there has been a crescendo of research interest in AD over the past decade, with 50% more papers published on the topic in the year 2007 than 1997 (Pubmed keyword search, MeSH term: Alzheimer disease). Throughout this period, one major area of research in AD has focused on the cognitive impairments exhibited by patients.
Clinicians and researchers have identified six cognitive domains that are commonly disturbed in patients suffering from AD: memory, executive functioning, language, visuospatial functioning, attention and affect. Of these disturbances, memory impairment is the central problem. Memory problems are among the most frequent reasons for admission to residential nursing facilities. A recent prospective, longitudinal study reported that delaying the onset of nursing home care for elderly adults with dementing illnesses by 1 month would result in annual savings of US$4 billion for the USA. Moreover, it has been suggested that community-dwelling individuals diagnosed with AD score higher on scales of quality of life than institutionalized patients at every stage of the disease. It has also been suggested that caregivers are more likely to avoid depression and to receive support from family and friends when patients exhibit fewer functional limitations. While preventive, disease-modifying and curative therapies for AD must be aggressively pursued as the over-riding goals of pharmaceutical research, in the interim drugs that effectively treat the memory impairments associated with AD may benefit patients, their families and society at large.
Abstract and Introduction
Abstract
Alzheimer's disease (AD) is a progressive neurodegenerative disease marked by a constellation of cognitive disturbances, the earliest and most prominent being impaired episodic memory. Episodic memory refers to the memory system that allows an individual to consciously retrieve a previously experienced item or episode of life. Many recent studies have focused on characterizing how AD pathology impacts particular aspects of episodic memory and underlying mental and neural processes. This review summarizes the findings of those studies and discusses the effects of current and promising treatments for AD on episodic memory. The goal of this review is to raise awareness of the strides that cognitive neuroscientists have made in understanding intact and dysfunctional memory. Knowledge of the specific memorial processes that are impaired in AD may be of great value to basic scientists developing novel therapies and to clinical researchers assessing the efficacy of those therapies.
Introduction
Alzheimer's disease (AD) is a progressive neurodegenerative disease that accounts for more than two-thirds of all cases of dementia. The most important risk factor for AD is age, followed by an APOE4 genotype. A 2007 report released by the Alzheimer's Association estimated that more than 5 million Americans are currently diagnosed with AD, while a Delphi consensus study projected that the global prevalence of AD will quadruple by the year 2040 to over 80 million cases in total. Just as this disease is often devastating at the individual and family levels, the high prevalence of AD means that it is also economically and societally burdensome. Indeed, AD represented the third most costly health condition in the USA in 2000, and is of growing financial relevance for health policy planning in other industrialized and developing nations. Perhaps due to mounting evidence regarding the gravity of the situation, there has been a crescendo of research interest in AD over the past decade, with 50% more papers published on the topic in the year 2007 than 1997 (Pubmed keyword search, MeSH term: Alzheimer disease). Throughout this period, one major area of research in AD has focused on the cognitive impairments exhibited by patients.
Clinicians and researchers have identified six cognitive domains that are commonly disturbed in patients suffering from AD: memory, executive functioning, language, visuospatial functioning, attention and affect. Of these disturbances, memory impairment is the central problem. Memory problems are among the most frequent reasons for admission to residential nursing facilities. A recent prospective, longitudinal study reported that delaying the onset of nursing home care for elderly adults with dementing illnesses by 1 month would result in annual savings of US$4 billion for the USA. Moreover, it has been suggested that community-dwelling individuals diagnosed with AD score higher on scales of quality of life than institutionalized patients at every stage of the disease. It has also been suggested that caregivers are more likely to avoid depression and to receive support from family and friends when patients exhibit fewer functional limitations. While preventive, disease-modifying and curative therapies for AD must be aggressively pursued as the over-riding goals of pharmaceutical research, in the interim drugs that effectively treat the memory impairments associated with AD may benefit patients, their families and society at large.
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