The progression of Alzheimer's disease and other dementias
Each person experiences dementia in their own way, but it can be helpful to think of the way the condition progresses as a series of stages. This factsheet outlines the characteristics of early-, middle- and late-stage Alzheimer's disease and briefly looks at how other forms of dementia progress.
Alzheimer's disease is a progressive illness. This means that the structure and chemistry of the brain become increasingly damaged over time. The person's ability to remember, understand, communicate and reason will gradually decline. Looking at Alzheimer's disease as a series of three stages can be a useful way of understanding the changes that occur over time. But it is important to realise that this view of Alzheimer's can only provide a rough guide to the course of the disease. This is because:
- some symptoms may appear earlier or later than indicated here, or not at all
- the stages may overlap - the person may need help with one task, but may be able to manage another activity on their own
- some symptoms, such as walking about, may appear at one stage and then vanish, while others such as memory loss will worsen over time.
The way that a person experiences Alzheimer's disease will depend on many factors, including their physical make-up, their emotional resilience, the medication they take and the support they can rely on.
Alzheimer's disease usually begins gradually with very minor changes in the person's abilities or behaviour. At the time, such signs are often mistakenly attributed to stress or bereavement or, in older people, to the normal process of ageing. It is often only when looking back that we realise that these signs were probably the beginnings of dementia.
Loss of memory for recent events is a common early sign. Someone with Alzheimer's may:
- forget about recent conversations or events
- repeat themselves
- become slower at grasping new ideas
- lose the thread of what is being said
- sometimes become confused
- show poor judgement, or find it harder to make decisions
- lose interest in other people or activities
- develop a readiness to blame others for taking mislaid items
- become unwilling to try out new things or adapt to change.
If you are caring for someone with Alzheimer's disease, there's a lot you can do in the early stages to help the person you are caring for maintain their independence. It may be tempting to do things for them, but they are more likely to retain their sense of self-worth if they are given the chance to do things for themselves, with support if necessary. (See our factsheet Staying involved and active (521) for more information.)
The person may also become anxious and agitated. They may experience distress over their failure to manage tasks and may need some reassurance. If this is the case, try to talk to them, and give them as much emotional support as you can.
As Alzheimer's disease progresses, the changes become more marked. The person will need more support to help them manage their day-to-day living. They may need frequent reminders or help to eat, wash, dress and use the toilet. They are likely to become increasingly forgetful - particularly of names - and may sometimes repeat the same question or phrase over and over because of the decline in their memory for recent events. They may also fail to recognise people or confuse them with others.
Some people at this stage become very easily upset, angry or aggressive - perhaps because they are feeling frustrated - or they may lose their confidence and become very clingy. Other symptoms may include:
- becoming confused about where they are, or walking off and becoming lost
- becoming muddled about time and getting up at night because they are mixing up night and day
- putting themselves or others at risk through their forgetfulness - for example, by not lighting the gas on the cooker
- behaving in ways that may seem unusual, such as going outside in their nightclothes
- experiencing difficulty with perception, and in some cases having hallucinations.
For more information about these symptoms and how to deal with them, see our factsheets on Unusual behaviour (525), Moving and walking about (501), and Sight, perception and hallucinations in dementia (527).
At this stage, the person with Alzheimer's will need even more help and will gradually become totally dependent on others for nursing care. Loss of memory may become very pronounced, with the person unable to recognise familiar objects or surroundings or even those closest to them, although there may be sudden flashes of recognition.
The person may also become increasingly frail. They may start to shuffle or walk unsteadily, eventually becoming confined to bed or a wheelchair. Other symptoms may include:
- difficulty in eating and, sometimes, swallowing
- considerable weight loss - although some people eat too much and put on weight
- incontinence - losing control of their bladder and sometimes their bowels as well
- gradual loss of speech, though they may repeat a few words or cry out from time to time.
The person may become restless, sometimes seeming to be searching for someone or something. They may become distressed or aggressive - especially if they feel threatened in some way. Angry outbursts may occur during close personal care, usually because the person does not understand what is happening. Those caring for the person should try not to take this personally, the person is not being aggressive deliberately.
Although the person may seem to have little understanding of speech, and may not recognise those around them, they may still respond to affection and to being talked to in a calm soothing voice. They may also enjoy scents, music, or stroking a pet.
On average, people with Alzheimer's disease live for eight to ten years after their symptoms begin. Life expectancy does, however, vary considerably depending on how old the person is. For example, people diagnosed in their 60s and early 70s can expect to live for around seven to ten years, whereas someone diagnosed in their 90s will, on average, live for about three years. The length of time that someone with dementia can expect to live for also depends on whether they were diagnosed early on or later in the disease.
For more information about this stage of Alzheimer's disease, see our factsheet on The later stages of dementia (417). For more detailed information about Alzheimer's disease in general, see What is Alzheimer's disease? (401).
In vascular dementia, which is commonly caused by a stroke or a series of small strokes, brain cells are deprived of oxygen and die. This can occur in distinct parts of the brain, leaving other areas relatively unaffected. It is sometimes difficult to tell whether people have Alzheimer's or vascular dementia. It is also not unusual to have a mixed form.
Unlike Alzheimer's disease, vascular dementia may progress in a 'stepped' manner. Symptoms may suddenly worsen due to stroke and then remain the same for some time. Months or years later, if another stroke occurs, symptoms may worsen again. However, when vascular dementia has been caused by several smaller strokes, a more gradual progression of symptoms is likely to be experienced. Importantly, if the person does not experience any additional strokes their symptoms may not worsen over time.
People with vascular dementia tend to maintain their personality and more normal levels of emotional responsiveness until the later stages of the disease. This sometimes means that people with vascular dementia are more aware of their condition and more prone to depression than people with Alzheimer's disease.
Each person will experience dementia differently. On average, people with vascular dementia live for around five years after symptoms begin. In many cases, the person's death will be caused by a stroke or heart attack.
For more information, see our factsheet What is vascular dementia? (402).
Fronto-temporal dementia (including Pick's disease)
This type of dementia is caused by damage to the frontal and/or temporal lobes of the brain. These are the areas responsible for our behaviour, our emotional responses and our language skills.
During the early stages of fronto-temporal dementia, memory for recent events may be unaffected. However, there may be other changes. For example, the disease may cause some people to appear uncharacteristically selfish and unfeeling. They may behave rudely, or may seem more easily distracted. Other symptoms may include loss of inhibition, ritualised behaviour or compulsions and a liking for sweet foods. In a small number of cases, a person's first problems may be with recalling the names of objects and comprehending words (semantic dementia) or with producing fluent speech (progressive non-fluent aphasia).
In later stages the symptoms are more similar to those seen in Alzheimer's disease. Each person's experience of fronto-temporal dementia will be different but on average people live for six to eight years after symptoms begin.
For more information, see our factsheet What is frontotemporal dementia? (404).
Dementia with Lewy bodies
Dementia with Lewy bodies gets its name from microscopic deposits that are found in the brains of people with the condition. These deposits cause the degeneration and eventual death of nerve cells in the brain.
Half or more of those affected by dementia with Lewy bodies also develop signs and symptoms of Parkinson's disease, such as slowness of movement, stiffness and tremor. They may also have difficulty in judging distances and are more prone to falls and fainting. People with this type of dementia also commonly experience visual hallucinations, paranoia and delusions.
Unlike Alzheimer's disease, in the early stages of Lewy body dementia the abilities of the affected person often fluctuate drastically from day to day, or even during the course of a single day. This can often be puzzling for those around them.
In the later stages, the symptoms are often very similar to those experienced in Alzheimer's disease. After the symptoms of dementia with Lewy bodies begin, people live on average for six to twelve years. However, each person will experience dementia with Lewy bodies differently.
For more information, see our factsheet What is dementia with Lewy bodies? (403).
Last reviewed: December 2011
Next review due: December 2013
Reviewed by: Dr Sebastian Crutch, Neuropsychologist, Dementia Research Centre, Institute of Neurology, UCL, London and Dr Greta Rait, Senior Clinical Lecturer, Department of Primary Care and Population Health, UCL, London.
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