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Dementia

Fact sheet
Updated September 2017


Key facts

  • Dementia is a syndrome in which there is deterioration in memory, thinking, behaviour and the ability to perform everyday activities.
  • Although dementia mainly affects older people, it is not a normal part of ageing.
  • Worldwide, around 47 million people have dementia, and there are nearly 10 million new cases every year.
  • Alzheimer's disease is the most common cause of dementia and may contribute to 60–70% of cases.
  • Dementia is one of the major causes of disability and dependency among older people worldwide.
  • Dementia has physical, psychological, social, and economical impact on carers, families and society.

Dementia is a syndrome – usually of a chronic or progressive nature – in which there is deterioration in cognitive function (i.e. the ability to process thought) beyond what might be expected from normal 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 deterioration in emotional control, social behaviour, or motivation.

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

Dementia is one of the major causes of disability and dependency among older people worldwide. It is overwhelming not only for the people who have it, but also for their carers and families. There is often a lack of awareness and understanding of dementia, resulting in stigmatization and barriers to diagnosis and care. The impact of dementia on carers, family and societies can be physical, psychological, social and economic.

Signs and symptoms

Dementia affects each person in a different way, depending upon the impact of the disease and the person’s personality 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 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 more restricting. These include:

  • becoming forgetful of recent events and people's names
  • becoming lost 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. Symptoms 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

There are many different forms, or causes, of dementia. Alzheimer's disease is the most common form of dementia 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). The boundaries between different forms of dementia are indistinct and mixed forms often co-exist.

Rates of dementia

Worldwide, around 47 million people have dementia, with nearly 60% living in low- and middle-income countries. Every year, there are nearly 10 million new cases.

The estimated proportion of the general population aged 60 and over with dementia at a given time is between 5 to 8 per 100 people.

The total number of people with dementia is projected to near 75 million in 2030 and almost triple by 2050 to 132 million. Much of this increase is attributable to the rising numbers of people with dementia living in low- and middle-income countries.

Treatment and care

There is no treatment currently available to cure dementia or to alter its progressive course. Numerous new treatments are being investigated in various stages of clinical trials.

Much can be, however, 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
  • detecting and treating challenging behavioural and psychological symptoms
  • 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 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. Some research has shown a relationship between the development of cognitive impairment and life-style related risk factors that are shared with other noncommunicable diseases. These risk factors include physical inactivity, obesity, unbalanced diets, tobacco use and harmful use of alcohol, diabetes, and midlife hypertension. Additional modifiable risk factors include depression, low educational attainment, social isolation, and cognitive inactivity.

Social and economic impacts

Dementia has significant social and economic implications in terms of direct medical costs, direct social costs, and the costs of informal care. In 2015, the total global societal cost of dementia was estimated to be US$ 818 billion, equivalent to 1.1% of global gross domestic product (GDP). The total cost as a proportion of GDP varied from 0.2% in low- and middle-income countries to 1. 4% in high-income countries.

Impact on families and carers

Dementia is overwhelming for the families of affected people and for their carers. Physical, emotional and economic pressures can cause great stress to families and carers, and support is required from the health, social, financial and legal systems.

Human rights

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 facilities for elderly 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 service provision to 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 – in areas such as: increasing awareness of dementia and establishing dementia-friendly initiatives; reducing the risk of dementia; diagnosis, treatment and care; research and innovation; and support for dementia carers.

An international surveillance platform, the Global Dementia Observatory, is being set up for policy-makers and researchers to facilitate monitoring and sharing of information on dementia policies, service delivery, epidemiology and research.

WHO has developed iSupport, an e-health solution that provides information and skills training for carers of people living with dementia. The first study of the usability and effectiveness of iSupport is taking place in India.

Dementia is also one of the priority conditions in the WHO Mental Health Gap Action Programme (mhGAP), which aims to scale-up care for mental, neurological and substance use disorders, particularly in low- and middle-income countries.