How long does Alzheimer’s Disease last?

Every person affected by dementia will experience it in their own unique way. Although each individual will have problems with thought, memory and communication, the pattern and speed of progression of the disease will vary from one person to another.

Alzheimers disease

In Alzheimer’s disease there is increasing damage to the cells in the brain, so the symptoms get worse over time. The brain isn’t just in charge of our minds; it also controls our bodily systems. This means that Alzheimer’s is eventually terminal, because the heart and lungs will gradually fail. On average, someone with Alzheimer's disease will live for between four and eight years after their diagnosis. However, this can vary enormously depending on age and general health, some people can live as long as 20 years and other frail or elderly people may be vulnerable to infections and illnesses that could lead to an earlier death.

Preclinical Alzheimer’s disease

The brain changes of Alzheimer’s start many years before any signs of the disease become apparent. This stage can last up to a decade, with gradually increasing brain damage occurring before symptoms are noticeable.

Mild Alzheimer’s disease

In the early stages, people with dementia can usually function independently and continue to live a full life. However, memory lapses, forgetting words and names and planning complex tasks can be increasingly problematic. Eventually, family members may notice that there are issues and doctors can diagnose the disease. Although there is still no cure for Alzheimer’s, an early diagnosis can help someone develop strategies to live with the condition, slow the progress and plan for the future so they can live well with the disease. Mild Alzheimer’s can last between two and four years and the symptoms include:

  • Forgetfulness, especially for recent events.
  • Difficulties with complex tasks like planning events and balancing family finances.
  • Lapses in judgement which can make them vulnerable to scams and opportunists.
  • Getting lost.
  • Misplacing things.
  • Personality changes including becoming withdrawn, irritable or inappropriate.
  • Struggling to find the word and express ideas.
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      Moderate Alzheimer's disease

      In the middle stages of Alzheimer’s, the increasing brain damage leads to a gradual deterioration in function. Individuals may have greater difficulty paying bills and there can be an escalation in memory loss and confusion. Moderate Alzheimer's is often the longest stage. It typically lasts between four and ten years, with greater care and support needed as the disease progresses. Symptoms include:

      • Deepening confusion leading to individuals becoming disorientated in time and place.
      • Wandering can become a problem, with people trying to seek out places that feel safe and familiar.
      • Greater memory loss. As well as recent events, they may forget experiences from their own history and significant things like their address or phone number.
      • Communication can be more challenging as it becomes difficult to find the right words, process their thoughts and express themselves coherently.
      • Some support may be needed with daily activities, like dressing appropriately for the weather, bathing and grooming. They may have an occasional accident, but incontinence is not usually a significant problem at this stage.
      • Personality changes can become more evident. Individuals may become paranoid and think that people are stealing from them, that their partner is plotting against them or having an affair. Some people may suffer distressing hallucinations, seeing or hearing things that aren’t really there.
      • Agitation and restlessness can be an increasing problem, particularly later in the day when it’s known as ‘sun-downing’.
        • Severe Alzheimer's disease

          In the final stage of Alzheimer’s, the disease affects an individual’s ability to communicate, care for themselves and respond to their environment. Eventually, the brain damage can make it difficult to move, swallow and control their bowels and bladder. At this stage, people are vulnerable to infections like pneumonia and eventually the body systems will fail, leading to death. Severe Alzheimer’s can last between one and three years with individuals needing care around the clock. At this difficult and distressing time, professional home carers can help to ease the family burden and ensure your loved one spends their final days in comfort and dignity.

Dr Jane Gilbert
Experienced health writer and TV presenter
Jane has over 20 years’ experience as a health writer and TV presenter. Jane writes on a wide variety of clinical and care topics – from explaining the latest studies and research to unpacking conditions and discussing treatment options. Jane holds a MBBS degree from Imperial College, London and spent seven years working in the NHS.