The progression of Alzheimer's disease and other dementias

3. Alzheimer's disease

Alzheimer’s is the most common type of dementia and the most studied. Its progression can be summarised in three stages. Progression of the other common dementias can then be compared with Alzheimer’s disease.

Each type of dementia tends to have particular early symptoms, because different parts of the brain are affected first. Later on, as damage spreads to more areas of the brain, the symptoms of different types of dementia tend to become more similar. By the late stage, the person will need a high level of care, whatever type of dementia they have.

Early (‘mild’) stage

Alzheimer’s disease usually begins with very minor changes in the person’s abilities or behaviour. At the time, such signs can often be mistakenly attributed to stress or bereavement or, in older people, to the normal process of ageing. It is often only when looking back that it is realised that these signs were probably the beginnings of dementia.

Loss of memory of recent events is a common early symptom. The person will have difficulty recalling things that happened recently and also with learning new information. Someone with Alzheimer’s may:

  • mislay items around the house
  • forget recent conversations or events
  • struggle to find the right word in conversation or lose the thread of what is being said
  • become slower at grasping new ideas and unwilling to try out new things
  • become confused or lose track of the day or date
  • show poor judgement, or find it harder to plan or make decisions
  • have problems judging distance or seeing objects in three dimensions (eg when navigating stairs or parking the car)
  • lose interest in other people or activities.

If you are caring for someone with Alzheimer’s disease, there’s a lot you can do in the early stages to help them maintain their independence. It may be tempting to do things for them, but they are more likely to retain their sense of self-worth and independence if they are given the chance to do things for themselves, with support if necessary. Focus on what the person can do, rather than what they cannot. Explore how things can be achieved in a different way.
For more information see our page on staying involved and active.

The person may also become anxious, irritable or depressed. They may experience distress over their failure to manage tasks and may need some reassurance. If this is the case, talk to them and give them as much emotional support as you can. For more information see our page on depression and anxiety.

Middle (‘moderate’) stage

As Alzheimer’s disease progresses, the changes become more marked. The person will need more support to help them manage their day-to-day life. 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 sentence over and over. They may also fail to recognise people or confuse them with others. At this stage, the person might put themselves or others at risk through their forgetfulness, for example by not lighting the gas on the cooker or forgetting to take medication.

Some people at this stage become very easily upset, angry or aggressive – perhaps because they are feeling frustrated or because they misinterpret what is happening – or they may lose their confidence and need a lot more support or reassurance. Other symptoms may include:

  • becoming confused about where they are, or walking off and becoming lost
  • muddling up time and getting up at night because they are mixing up night and day
  • behaving in ways that may seem unusual, such as going outside in their nightclothes, becoming very agitated or unknowingly behaving in socially inappropriate ways
  • experiencing difficulty with perception and, in some cases, having delusions (strongly believing things that are not true) or, less often, hallucinations (usually, seeing things that are not really there).

Changes in behaviour tend to be most common from the middle stage of dementia onwards and are one of the most challenging aspects of dementia for carers. For more information about these symptoms and how to deal with them see our pages on symptoms.

Late (‘severe’) stage

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, surroundings or even those closest to them, although there may be sudden flashes of recognition.

The person may also become increasingly weak. They may start to shuffle or walk unsteadily, eventually spending more time in bed or a wheelchair. Other symptoms may include:

  • difficulty 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 the person 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 deliberately aggressive. It is also important to consider that the person may be experiencing pain which they cannot express verbally. Painkillers can often help.

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. However, life expectancy does vary considerably depending on how old the person is and other factors as mentioned above. For example, people whose symptoms started in their 60s or early 70s can expect to live for around seven to ten years, whereas someone whose symptoms started in their 90s will, on average, live for about three years. The length of time that someone with Alzheimer’s can expect to live for also depends on whether they were diagnosed early on or later in the course of the disease.

For more information about this stage of Alzheimer’s disease see our page on the later stages of dementia. For more detailed information about Alzheimer’s disease in general see our page on Alzheimer’s disease.