Dementia is an umbrella term for a collection of symptoms that are caused by disorders affecting the brain and impact on memory, thinking, behaviour and emotion. The most common is Alzheimer’s disease, which affects 50-60% of people with dementia.  Other types of dementia include vascular dementia, Lewy body dementia and fronto-temporal dementia. Dementia can also sometimes affect people who are under the age of 65. This is known as young onset dementia. Our brains are made up of over 86 billion nerve cells – more than the stars in the Milky Way. Dementia damages nerve cells so they are no longer able to communicate effectively and this impacts on how our body functions.

The specific symptoms a person living with dementia experiences will depend upon what parts of the brain are affected and/or the specific disease that is causing their dementia. Symptoms may include:

• loss of memory
• difficulty in finding the right words or understanding what people are saying
• difficulty in performing previously routine tasks
• personality and mood changes

Although each person will experience dementia in their own way, eventually those affected will be unable to care for themselves and need help with all aspects of daily life. Dementia is the leading cause of disability and dependency among the elderly.

Dementia affects more than 50 million people worldwide, with a new case of dementia occurring somewhere in the world every 3 seconds. Dementia can also affect individuals under the age of 65 (young onset dementia). Greater awareness and understanding of dementia is important to challenge the myths and misconceptions that surround the condition.

There is currently no cure for most types of dementia, but treatment and support are available.

• Dementia is a syndrome in which there is deterioration in cognitive function beyond what might be expected from the usual consequences of biological ageing.
• Although dementia mainly affects older people, it is not an inevitable consequence of ageing.
• Currently more than 55 million people live with dementia worldwide, and there are nearly 10 million new cases every year.
• Dementia results from a variety of diseases and injuries that primarily or secondarily affect the brain. Alzheimer's disease is the most common form of dementia and may contribute to 60-70% of cases.
• Dementia is currently the seventh leading cause of death among all diseases and one of the major causes of disability and dependency among older people globally.
• Dementia has physical, psychological, social and economic impacts, not only for people living with dementia, but also for their carers, families and society at large.

Dementia is a syndrome – usually of a chronic or progressive nature – that leads to deterioration in cognitive function (i.e. the ability to process thought) beyond what might be expected from the usual consequences of biological ageing. It affects memory, thinking, orientation, comprehension, calculation, learning capacity, language, and judgement. Consciousness is not affected. The impairment in cognitive function is commonly accompanied, and occasionally preceded, by changes in mood, emotional control, behaviour, or motivation.

Dementia results from a variety of diseases and injuries that primarily or secondarily affect the brain, such as Alzheimer's disease or stroke.

Dementia is currently the seventh leading cause of death among all diseases and one of the major causes of disability and dependency among older people worldwide. Dementia has physical, psychological, social and economic impacts, not only for people living with dementia, but also for their carers, families and society at large. There is often a lack of awareness and understanding of dementia, resulting in stigmatization and barriers to diagnosis and care.

Dementia affects each person in a different way, depending upon the underlying causes, other health conditions and the person’s cognitive functioning before becoming ill. The signs and symptoms linked to dementia can be understood in three stages.

Early stage: the early stage of dementia is often overlooked because the onset is gradual. Common symptoms may include:

• forgetfulness
• losing track of the time
• becoming lost in familiar places.

Middle stage: as dementia progresses to the middle stage, the signs and symptoms become clearer and may include:

• becoming forgetful of recent events and people's names
• becoming confused while at home
• having increasing difficulty with communication
• needing help with personal care
• experiencing behaviour changes, including wandering and repeated questioning

Late stage: the late stage of dementia is one of near total dependence and inactivity. Memory disturbances are serious and the physical signs and symptoms become more obvious and may include:

• becoming unaware of the time and place
• having difficulty recognizing relatives and friends
• having an increasing need for assisted self-care
• having difficulty walking
• experiencing behaviour changes that may escalate and include aggression.

There are many different forms of dementia. Alzheimer's disease is the most common form and may contribute to 60-70% of cases. Other major forms include vascular dementia, dementia with Lewy bodies (abnormal aggregates of protein that develop inside nerve cells), and a group of diseases that contribute to frontotemporal dementia (degeneration of the frontal lobe of the brain). Dementia may also develop after a stroke or in the context of certain infections such as HIV, harmful use of alcohol, repetitive physical injuries to the brain (known as chronic traumatic encephalopathy) or nutritional deficiencies. The boundaries between different forms of dementia are indistinct and mixed forms often co-exist.

Rates of dementia

Worldwide, around 55 million people have dementia, with over 60% living in low- and middle-income countries. As the proportion of older people in the population is increasing in nearly every country, this number is expected to rise to 78 million in 2030 and 139 million in 2050.

Treatment and care

There is currently no treatment available to cure dementia. Anti-dementia medicines and disease-modifying therapies developed to date have limited efficacy and are primarily labeled for Alzheimer’s disease, though numerous new treatments are being investigated in various stages of clinical trials.

Additionally, much can be offered to support and improve the lives of people with dementia and their carers and families. The principal goals for dementia care are:

• early diagnosis in order to promote early and optimal management
• optimizing physical health, cognition, activity and well-being
• identifying and treating accompanying physical illness
• understanding and managing behaviour changes
• providing information and long-term support to carers.

Although age is the strongest known risk factor for dementia, it is not an inevitable consequence of biological ageing. Further, dementia does not exclusively affect older people – young onset dementia (defined as the onset of symptoms before the age of 65 years) accounts for up to 9% of cases. Studies show that people can reduce their risk of cognitive decline and dementia by being physically active, not smoking, avoiding harmful use of alcohol, controlling their weight, eating a healthy diet, and maintaining healthy blood pressure, cholesterol and blood sugar levels. Additional risk factors include depression, social isolation, low educational attainment, cognitive inactivity and air pollution.

Social and economic impact

Dementia has significant social and economic implications in terms of direct medical and social care costs, and the costs of informal care. In 2019, the estimated total global societal cost of dementia was US$ 1.3 trillion, and these costs are expected to surpass US$ 2.8 trillion by 2030 as both the number of people living with dementia and care costs increase. 

Impact on families and carers

In 2019, informal carers (i.e. most commonly family members and friends) spent on average 5 hours per day providing care for people living with dementia. This can be overwhelming . Physical, emotional and financial pressures can cause great stress to families and carers, and support is required from the health, social, financial and legal systems. Fifty percent of the global cost of dementia is attributed to informal care.

Fronto-temporal dementias are a rare cause of dementia. They are sometimes 

Fronto-temporal dementias are a relatively rare cause of dementia which typically develop at an earlier age than Alzheimer’s disease. The frontal lobe of the brain is particularly affected in early stages.

Frontal lobe dementia is caused in a similar way to Alzheimer’s disease in that it involves a progressive decline in a person’s mental abilities over a number of years. Damage to brain cells is more localised than in Alzheimer’s disease and usually begins in the frontal lobe of the brain.

 Symptoms

• The frontal lobe governs people’s mood and behaviour. The person’s mood and behaviour may become fixed and difficult to change, making them appear selfish and unfeeling
• The person does not usually have sudden lapses of memory which are characteristic of Alzheimer’s disease.

Key facts

• Around 3 billion people cook using polluting open fires or simple stoves fuelled by kerosene, biomass (wood, animal dung and crop waste) and coal.
• Each year, close to 4 million people die prematurely from illness attributable to household air pollution from inefficient cooking practices using polluting stoves paired with solid fuels and kerosene.
• Household air pollution causes noncommunicable diseases including stroke, ischaemic heart disease, chronic obstructive pulmonary disease (COPD) and lung cancer.
• Close to half of deaths due to pneumonia among children under 5 years of age are caused by particulate matter (soot) inhaled from household air pollution.

Indoor air pollution and household energy: the forgotten 3 billion

Around 3 billion people still cook using solid fuels (such as wood, crop wastes, charcoal, coal and dung) and kerosene in open fires and inefficient stoves. Most of these people are poor, and live in low- and middle-income countries.

These cooking practices are inefficient, and use fuels and technologies that produce high levels of household air pollution with a range of health-damaging pollutants, including small soot particles that penetrate deep into the lungs. In poorly ventilated dwellings, indoor smoke can be 100 times higher than acceptable levels for fine particles. Exposure is particularly high among women and young children, who spend the most time near the domestic hearth.

Impacts on health

3.8 million people a year die prematurely from illness attributable to the household air pollution caused by the inefficient use of solid fuels and kerosene for cooking. Among these 3.8 million deaths:

• 27% are due to pneumonia
• 18% from stroke
• 27% from ischaemic heart disease
• 20% from chronic obstructive pulmonary disease (COPD)
• 8% from lung cancer.

Pneumonia

Exposure to household air pollution almost doubles the risk for childhood pneumonia and is responsible for 45% of all pneumonia deaths in children less than 5 years old. Household air pollution is also risk for acute lower respiratory infections (pneumonia) in adults, and contributes to 28% of all adult deaths to pneumonia.

Chronic obstructive pulmonary disease

One in four or 25% of deaths from chronic obstructive pulmonary disease (COPD) in adults in low- and middle-income countries are due to exposure to household air pollution. Women exposed to high levels of indoor smoke are more than twice as likely to suffer from COPD than women who use cleaner fuels and technologies. Among men (who already have a heightened risk of COPD due to their higher rates of smoking), exposure to household air pollution nearly doubles that risk.

Stroke

12% of all deaths due to stroke can be attributed to the daily exposure to household air pollution arising from cooking with solid fuels and kerosene.

Ischaemic heart disease

Approximately 11% of all deaths due to ischaemic heart disease, accounting for over a million premature deaths annually, can be attributed to exposure to household air pollution.

Lung cancer

Approximately 17% of lung cancer deaths in adults are attributable to exposure to carcinogens from household air pollution caused by cooking with kerosene or solid fuels like wood, charcoal or coal. The risk for women is higher, due to their role in food preparation.

Other health impacts and risks

More generally, small particulate matter and other pollutants in indoor smoke inflame the airways and lungs, impairing immune response and reducing the oxygen-carrying capacity of the blood.

There is also evidence of links between household air pollution and low birth weight, tuberculosis, cataract, nasopharyngeal and laryngeal cancers.

Disproportionate impact on women

Globally, dementia has a disproportionate impact on women. Sixty-five percent of total deaths due to dementia are women, and disability-adjusted life years (DALYs) due to dementia are roughly 60% higher in women than in men. Additionally, women provide the majority of informal care for people living with dementia, accounting for 70% of carer hours.

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The alarm bells started going off for neuroscientist Roberta Diaz Brinton, Ph.D., three decades ago, when she saw just how hard women in particular were being hit by Alzheimer’s disease. Consider these current stats: Nearly two-thirds of patients diagnosed with the brain disorder are women—a staggering one in five of us will be diagnosed by the time we’re 65—and by 2050, as many as 9 million women may end up with the disease. It’s even worse for African Americans, who are two to three times as likely as non-Hispanic whites to develop Alzheimer’s.

But when Brinton, the director of the Center for Innovation in Brain Science at the University of Arizona (and whose work has been supported for years by the Women’s Alzheimer’s Movement), went looking for answers, she found the status quo response to these stats unsatisfying at best and maddening at worst.

“I kept hearing over and over that it was because women live longer than men,” she says. “But we only live about four and a half years longer. That does not explain our twofold greater lifetime risk.”

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It also doesn’t explain why a number of other brain-health issues affect women far more than men: Women are twice as likely as men to develop certain types of brain tumors, nearly twice as likely to deal with depression, and three times as likely to get headaches. We’re also much more likely to have a stroke and to develop an autoimmune disorder that affects the brain like multiple sclerosis.

Join the conversation about brain health: Top experts shared their insights and advice in You & Your Brain, a web series hosted by Prevention, HealthyWomen, and the Women’s Alzheimer’s Movement.

So Brinton and a number of her colleagues around the world started focusing on what might be going on specifically in women’s brains—beyond aging and unlucky genes—to lead to such higher rates of brain disease.

Human rights

Unfortunately, people with dementia are frequently denied the basic rights and freedoms available to others. In many countries, physical and chemical restraints are used extensively in care homes for older people and in acute-care settings, even when regulations are in place to uphold the rights of people to freedom and choice.

An appropriate and supportive legislative environment based on internationally-accepted human rights standards is required to ensure the highest quality of care for people with dementia and their carers.

WHO recognizes dementia as a public health priority

WHO recognizes dementia as a public health priority. In May 2017, the World Health Assembly endorsed the Global action plan on the public health response to dementia 2017-2025. The Plan provides a comprehensive blueprint for action – for policy-makers, international, regional and national partners, and WHO as in the following areas: addressing dementia as a public health priority; increasing awareness of dementia and creating a dementia-inclusive society; reducing the risk of dementia; diagnosis, treatment and care; information systems for dementia; support for dementia carers; and, research and innovation

An international surveillance platform, the Global Dementia Observatory (GDO), has been established for policy-makers and researchers to facilitate monitoring and sharing of information on dementia policies, service delivery, epidemiology and research. As a complement to the GDO, WHO launched the GDO Knowledge Exchange Platform, which is a repository of “good practices” in the area of dementia with the goal of fostering multi-directional exchange between regions, countries and individuals to facilitate action globally.

WHO has developed Towards a dementia plan: a WHO guide plan: a WHO guide, which provides guidance to Member States in creating and operationalizing a dementia plan. The guide is closely linked to WHO’s GDO and includes associated tools such as a checklist to guide the preparation, development and implementation of a dementia plan. It can also be used for stakeholder mapping and priority setting.

WHO’s Guidelines on risk reduction of cognitive decline and dementia provide evidence- based recommendations on interventions for reducing modifiable risk factors for dementia, such as physical inactivity and unhealthy diets, as well as controlling medical conditions linked to dementia, including hypertension and diabetes. The recently released mDementia handbook provides guidance on implementing mHealth programmes such as two-way messaging using mobile phone technology, which also contains a module and message libraries on dementia risk reduction.

Dementia is also one of the priority conditions in the WHO Mental Health Gap Action Programme (mhGAP), which is a resource for generalists, particularly in low- and middle-income countries, to help them provide first-line care for mental, neurological and substance use disorders.

WHO’s iSupport, a knowledge and skills training programme for carers of people living with dementia is available as an online course and a hardcopy manual. iSupport Lite includes easy-to-read posters and a brief video  that can act as a quick reference or a refresher, reinforcing previously-acquired caregiving skills and knowledge.

In July 2021, WHO released “Towards a dementia-inclusive society: WHO toolkit for dementia-friendly initiatives”, which to support countries in establishing, scaling and evaluating dementia-friendly initiatives to foster societies where people with dementia and their carers can meaningfully participate.

WHO is also developing a Dementia Research Blueprint, together with researchers and academics around the world, to synergize efforts and harmonize the global dementia research and innovation agenda.