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.

Signs and symptoms

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.

Common forms of dementia

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.

Risk factors and prevention

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.

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.

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 response

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, 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