Description

Dementia disproportionately impacts women, who account for 65% of deaths and around 60% more Disability-Adjusted Life Years (DALYs) due to dementia compared with men. Dementia is the seventh most common cause of death globally and a leading cause of disability among older adults. An estimated 55.2 million people globally were living with dementia in 2019; as the world's population ages, it has been estimated that prevalence could rise to 78 million people with dementia by 2030 and 139 million by 2050. The burden of dementia is also higher in low-income and middle-income countries, which are home to more than 60% of people living with dementia and are expected to see the sharpest rises in dementia prevalence over the coming decades due to their rapidly ageing populations.

Potential for Disease Management

Without considerable coordinated action, the world faces both a growing burden of dementia and widening inequalities between and within countries. Dementia carries substantial social and economic costs. Caring for those with the disease was estimated to cost US$1.3 trillion in 2019 globally, which could rise to $1.7 trillion by 2030. In high-income countries, more than a quarter of the societal costs of dementia come from providing long-term care to patients a provision that will become less sustainable as populations age. Importantly, the potential for prevention and for disease management to reduce its severity and impact on patients’ lives are high.

Spiraling costs could also see diagnosis and treatment become unattainable to a growing proportion of the world's population. Almost 50% of the global care costs of dementia are from informal care, provided by family members and friends; however, the share of costs from informal care grows inversely with national income, accounting for as much as 85% of costs in low-income countries. Informal carers bear an enormous proportion of the care work providing an estimated 133 billion hours of care in 2019. Women provide around 70% of all informal dementia care, highlighting another way in which the disease disproportionately impacts the lives of women. Without action to reduce the prevalence and severity of dementia, the treatment and care needs over the coming decades could overwhelm health-care systems, overburden informal carers, and threaten progress on gender equity.

While the need to address dementia remains urgent, tackling the disease appears to have slipped from national priorities. Just a quarter of countries have a national plan for dementia, and many of these plans have expired or are due to expire soon. Even fewer countries have committed definite funding or legal mechanisms to implement dementia strategies. The potential health, societal, and economic costs of dementia are enormous, but they are also substantially avoidable if governments implement national plans to prevent, mitigate, and fairly manage dementia. Acting now will meaningfully improve later life for future generations and their families, and benefit society at large. The 2020 Lancet Commission on Dementia estimated that around 40% of the global burden of dementia could be attributable to 12 modifiable risk factors: low education, traumatic brain injury, physical inactivity, obesity, diabetes, excessive alcohol consumption, hypertension, smoking, depression, hearing loss, social isolation, and air pollution. Knowing the importance of these risk factors provides opportunities for intervention throughout life, and at both the population and individual levels. Addressing these health risks could also reduce inequalities in the burden of dementia over the coming decades particularly in settings in which exposure to these modifiable risk factors is greater or growing.

Reducing these common risk factors would produce extensive co-benefits, including a reduction in non-communicable diseases more broadly. Acting on the climate crisis is a clear, yet still neglected, priority for public health. There is now a large body of work making a clear link between climate change and health. The impacts of climate change on health can be direct relating primarily to changes in the frequency of extreme weather (such as heat waves, drought, fires, floods, or storms) and indirect, through changes on ecosystems (for example, water-borne diseases, and air pollution) and through effects mediated by human systems (such as occupational impacts, under nutrition, mental health, but also migration and conflict).

Health Co-Benefits of Mitigation

The health co-benefits of mitigation have been comprehensively set out in reports such as the 2015 Lancet Commission on Health and Climate Change. Reductions in emissions reduce air pollution and respiratory diseases; safe active transport decreases road traffic injuries and can reduce the incidence of obesity, diabetes, and heart disease. Crucially, the response to climate change can bring immense benefits for human health, with cleaner air, healthier diets, more liveable cities, and can reduce the risk factors of future infectious diseases. Taking public health co-benefits into account could make important contributions to offsetting the costs of mitigation strategies.

Mitigating climate change is also a question of justice. Climate change disproportionately affects the most vulnerable in society’s older people, children, disadvantaged socioeconomic groups, and those living in the most fragile countries. According to the Lancet Countdown report, heat-related deaths in the elderly have increased by more than 50% in the past two decades. Heat effects on labour capacity could result in losses in earnings equivalent to 4–6% of GDP in some low-middle-income countries. Climate change threatens to undermine the past 50 years of development gains in public health. The public health community has a crucial part to play in accelerating progress to tackle climate change.

While most world leaders might recognise climate threats to health, their current actions are deeply insufficient. Governments have signed the Paris Agreement and accepted the conclusions of the latest IPCC report (the so-called Summary for Policymakers). However, within G20 countries collectively responsible for 80% of emissions 12 countries (China, India, Brazil, Russia, South Africa, Saudi Arabia, Mexico, Australia, Turkey, South Korea, Indonesia, and Japan) have failed to strengthen their emissions targets as requested by the Paris Agreement, according to The Times. This lack of leadership commitment augurs badly for the COP26 UN Climate Summit, to be held in November, 2021.

Ahead of the Summit, and alongside the publication of the annual Lancet Countdown on Climate and Health, The Lancet Public Health will be publishing the second report of the Lancet Countdown Climate and Health for China (the world's largest carbon emitter and home of a fifth of the world's population). The journal will also publish an introduction to the climate change and health project in Europe to support policy makers in their decisions.