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 50 million people have dementia, and there are nearly 10 million new cases every year.
• Alzheimer's disease is the most common form 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 a physical, psychological, social, and economic impact, not only on people with dementia, but also on their carers, families and society at large.

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 results from 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 can be 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 society at large 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 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). The boundaries between different forms of dementia are indistinct and mixed forms often co-exist.

Rates of dementia

Worldwide, around 50 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 5-8%.

The total number of people with dementia is projected to reach 82 million in 2030 and 152 in 2050. 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.

However, 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
• 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. Studies show that people can reduce their risk of dementia by getting regular exercise, 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, low educational attainment, social isolation, and cognitive inactivity.

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