Safeguarding cognitive health in an ageing population

Abstract

Of the 6·5 billion or so people alive in 2006, an unprecedented proportion of us—around one in ten—are over 60 years of age. By 2050, when the global population will likely have increased to over 9 billion, this proportion will have risen to about one in five. The rapid increase in the number of people living to old age and increasing longevity in many parts of the world are testimony to improved nutrition and health. But the burgeoning of the upper age ranges poses many new economic, social, and health challenges for the coming century and beyond.The growing burden of age-related chronic diseases is one of the most pressing health issues of the present day. Because many neurological disorders are diseases of old age, the ageing global population will create an ever-growing burden of neurological disease, not least dementia. In late 2005, the authors of a study published in The Lancet estimated that the global prevalence of dementia would more than triple from 24·3 million people today to 81·1 million in 2040. Moreover, the incidence of cognitive decline that does not meet the threshold of dementia will also increase.Researchers in the USA—including collaborators from the National Institutes of Aging, Mental Health, and Neurological Disorders and Stroke—have written The NIH Cognitive and Emotional Health Project: report of the Critical Evaluation Study Committee recently published by the US Alzheimer's Association. This review of cognitive and emotional health tries to identify the major contributing factors to successful ageing in large longitudinal cohort studies of cognitive or emotional decline. Among the factors identified in the 36 studies summarised, five recurring themes emerged: cardiovascular factors, psychosocial factors, genetic factors, physical activity, and chronic illness. The report also highlights a bidirectional relation between emotional symptoms, such as depression, and adverse cognitive changes. In addition, socioeconomic status and education history also seem to influence late-life cognitive health.This report is a sign of the rising trend of research to investigate general outcomes, such as “good cognitive health” or “successful ageing”, rather than disease-specific outcomes, and the authors recommend that future research should “pursue the avenue of brain health maintenance with as much vigour as is brought to the quest to understand the pathophysiology of disease”. But whether such concepts are really useful for clinical research is debatable. Cognitive and emotional health are, after all, difficult to define, especially among elderly people in which some changes in these domains are to be expected. Many researchers prefer more easily quantifiable and definable measures of pathological changes, such as clinical scales or MRI measures of disease progression. Several other programmes have also begun to investigate health in terms of positive cognitive health outcomes including the ACTIVE trial of cognitive intervention in elderly people and the UK Medical Research Council Cognitive Function Ageing Study. These investigations into “brain health” might identify effects not noted in studies that use disease-specific outcomes.Many of the new report's findings seem to be old news: hardly a month goes by without a study reporting the benefits of social, leisure, or physical activity on cognition or risk of Alzheimer's disease in elderly people. However, the authors make several recommendations for furthering investigations into the risk factors identified: the first and foremost of these should be hypothesis-based sytematic reviews to test the associations. Should the putative risk factors be confirmed, the next stage will be to devise public-health campaigns to implement prevention measures. Rather than waiting for the results of further studies, the US Alzheimer's Association and Centers for Disease Control and Prevention have launched a pilot programme to develop public information strategies.Although the report does not generate testable hypotheses or investigate specific disease outcomes, it does highlight potentially valuable avenues for future investigation into the prevention of cognitive decline. We have an increasingly thorough knowledge of factors that contribute to certain aspects of health in elderly people—for example, a healthy diet and some exercise protect cardiovascular health. We now need to consider strategies to avert a pending crisis of neurological disease burden. Just as advice now recommends five portions of fruit and vegetables a day and regular exercise to maintain cardiovascular health, perhaps, in addition to these general health measures, the 2 billion people over the age of 65 in 2050 will be advised to complete five crosswords a week and engage in regular social activity to stave off the ravages of age-related cognitive decline. Of the 6·5 billion or so people alive in 2006, an unprecedented proportion of us—around one in ten—are over 60 years of age. By 2050, when the global population will likely have increased to over 9 billion, this proportion will have risen to about one in five. The rapid increase in the number of people living to old age and increasing longevity in many parts of the world are testimony to improved nutrition and health. But the burgeoning of the upper age ranges poses many new economic, social, and health challenges for the coming century and beyond. The growing burden of age-related chronic diseases is one of the most pressing health issues of the present day. Because many neurological disorders are diseases of old age, the ageing global population will create an ever-growing burden of neurological disease, not least dementia. In late 2005, the authors of a study published in The Lancet estimated that the global prevalence of dementia would more than triple from 24·3 million people today to 81·1 million in 2040. Moreover, the incidence of cognitive decline that does not meet the threshold of dementia will also increase. Researchers in the USA—including collaborators from the National Institutes of Aging, Mental Health, and Neurological Disorders and Stroke—have written The NIH Cognitive and Emotional Health Project: report of the Critical Evaluation Study Committee recently published by the US Alzheimer's Association. This review of cognitive and emotional health tries to identify the major contributing factors to successful ageing in large longitudinal cohort studies of cognitive or emotional decline. Among the factors identified in the 36 studies summarised, five recurring themes emerged: cardiovascular factors, psychosocial factors, genetic factors, physical activity, and chronic illness. The report also highlights a bidirectional relation between emotional symptoms, such as depression, and adverse cognitive changes. In addition, socioeconomic status and education history also seem to influence late-life cognitive health. This report is a sign of the rising trend of research to investigate general outcomes, such as “good cognitive health” or “successful ageing”, rather than disease-specific outcomes, and the authors recommend that future research should “pursue the avenue of brain health maintenance with as much vigour as is brought to the quest to understand the pathophysiology of disease”. But whether such concepts are really useful for clinical research is debatable. Cognitive and emotional health are, after all, difficult to define, especially among elderly people in which some changes in these domains are to be expected. Many researchers prefer more easily quantifiable and definable measures of pathological changes, such as clinical scales or MRI measures of disease progression. Several other programmes have also begun to investigate health in terms of positive cognitive health outcomes including the ACTIVE trial of cognitive intervention in elderly people and the UK Medical Research Council Cognitive Function Ageing Study. These investigations into “brain health” might identify effects not noted in studies that use disease-specific outcomes. Many of the new report's findings seem to be old news: hardly a month goes by without a study reporting the benefits of social, leisure, or physical activity on cognition or risk of Alzheimer's disease in elderly people. However, the authors make several recommendations for furthering investigations into the risk factors identified: the first and foremost of these should be hypothesis-based sytematic reviews to test the associations. Should the putative risk factors be confirmed, the next stage will be to devise public-health campaigns to implement prevention measures. Rather than waiting for the results of further studies, the US Alzheimer's Association and Centers for Disease Control and Prevention have launched a pilot programme to develop public information strategies. Although the report does not generate testable hypotheses or investigate specific disease outcomes, it does highlight potentially valuable avenues for future investigation into the prevention of cognitive decline. We have an increasingly thorough knowledge of factors that contribute to certain aspects of health in elderly people—for example, a healthy diet and some exercise protect cardiovascular health. We now need to consider strategies to avert a pending crisis of neurological disease burden. Just as advice now recommends five portions of fruit and vegetables a day and regular exercise to maintain cardiovascular health, perhaps, in addition to these general health measures, the 2 billion people over the age of 65 in 2050 will be advised to complete five crosswords a week and engage in regular social activity to stave off the ravages of age-related cognitive decline. Global prevalence of dementia: a Delphi consensus studyWe believe that the detailed estimates in this paper constitute the best currently available basis for policymaking, planning, and allocation of health and welfare resources. Full-Text PDF