Stages of Alzheimer's Disease

Alzheimer's disease is the most common cause of dementia. It is caused by abnormal proteins, amyloid and tau, building up in the brain and gradually damaging brain cells. It usually progresses slowly, over many years, and is most often described in three stages: early (mild), middle (moderate) and late (severe). Before these, there's a long period when changes are happening in the brain but symptoms are absent or very mild.

The stages are only a rough guide. Everyone's experience is different, stages overlap, and it can be hard to say exactly which stage someone is in.

Before dementia: preclinical Alzheimer's and mild cognitive impairment

Preclinical Alzheimer's. Changes in the brain, such as amyloid plaques and tau tangles, begin a decade or more before any memory or thinking problems appear. People feel and function normally. Not everyone with these brain changes goes on to develop dementia.

Mild cognitive impairment (MCI). Some people then develop MCI: memory or thinking problems that are noticeable and can be measured on tests, but aren't bad enough to stop them managing everyday life. Symptoms can include forgetting appointments, conversations or recent events, and taking longer over decisions or complicated tasks. MCI has many causes, and not everyone with it develops dementia, but when it's caused by Alzheimer's changes in the brain it is the earliest symptomatic stage. See what is mild cognitive impairment?

Early stage (mild Alzheimer's)

In the early stage, a person can usually still live independently: drive, work, and take part in social activities. Memory problems are typically the first and most obvious symptom. Common signs include:

• forgetting recent events or conversations, or something just read
• trouble finding the right word or remembering names, especially of new people
• losing or misplacing things, including valuables
• increasing difficulty with planning, organising and familiar tasks
• getting lost in familiar places
• mood changes: anxiety, low mood, irritability or withdrawing from hobbies and people

Family and close friends often notice changes before others do. This is a good time to plan ahead, including legal and financial arrangements and wishes for future care, while the person can fully take part in decisions. Read more about early-stage dementia and subtle early symptoms.

Middle stage (moderate Alzheimer's)

The middle stage is usually the longest, often lasting several years. Symptoms become more noticeable and the person needs increasing help with daily life. They may:

• forget events or parts of their own personal history, and be unable to recall their address or phone number
• be confused about where they are or what day it is
• need help choosing the right clothes for the weather or occasion
• have changes in sleep, such as sleeping during the day and being restless at night
• be at higher risk of wandering and getting lost
• show changes in personality and behaviour, such as becoming suspicious, believing people are stealing from them, or repeating actions
• become frustrated or angry, especially in demanding situations
• start to have trouble controlling the bladder and bowels

Some people also start to see or hear things that aren't there (hallucinations). The person can still take part in activities with support, so it helps to focus on what they can still do and to simplify tasks. See what happens in the middle stage of dementia.

Late stage (severe Alzheimer's)

In the late stage, the person needs help with almost everything and usually round-the-clock care. They may:

• lose awareness of recent experiences and their surroundings
• lose most speech, though they may still say some words or phrases; communicating pain becomes difficult
• have increasing problems with walking, sitting and eventually swallowing
• lose weight and need a lot of help with eating
• become more vulnerable to infections, especially pneumonia

People at this stage can still benefit from comfort and connection, such as familiar music, gentle touch and a calm environment. Read more about end stage dementia.

How long does each stage last?

Every person is different, but as a very rough guide, the Alzheimer's Society suggests that across dementias the early stage lasts about two years, the middle stage two to four years, and the later stage one to two years. The middle stage is usually the longest.

Life expectancy

The Alzheimer's Association says that, on average, a person with Alzheimer's lives four to eight years after diagnosis, but some live 20 years or more, depending on their age when diagnosed and their other health conditions. Figures vary between sources partly because some count from when symptoms first started rather than from diagnosis. People usually die from complications such as pneumonia rather than from Alzheimer's itself. See dementia life expectancy for other types.

Treatment

There's no cure yet, but treatment can help:

• Donepezil, galantamine and rivastigmine are used for early to mid-stage Alzheimer's. They can help with symptoms such as memory and confusion for a time, but don't stop the disease progressing.
• Memantine is used in moderate or severe Alzheimer's, or for people who can't take the other medicines.
• Non-drug support, such as cognitive stimulation therapy, staying active and socially engaged, and help for carers, is important at every stage.

New treatments. Two drugs that target amyloid, lecanemab (Leqembi) and donanemab (Kisunla), have been shown to slow the decline in memory and thinking in some people with early Alzheimer's. They're licensed in the UK, but only for people in the early stage who meet strict criteria, and they need regular infusions and brain scans because of side effects such as brain swelling or small bleeds. At the time of writing they aren't available on the NHS, only privately, and NICE is reviewing its decision. They don't help people in the middle or late stages.

Alzheimer's compared with other types of dementia

Memory loss is usually the first symptom in Alzheimer's, which isn't always true of other types. Vascular dementia often starts with slow thinking and problems with planning, dementia with Lewy bodies with fluctuating alertness and visual hallucinations, and frontotemporal dementia with changes in personality, behaviour or language. As all types progress, symptoms become more similar. See:

• Stages of vascular dementia
• Stages of Lewy body dementia
• The 7 stages of frontotemporal dementia
• Frontotemporal dementia vs Alzheimer's

You may also see Alzheimer's described in seven stages using the Global Deterioration Scale, which splits the same course into finer steps. Read the 7 stages of dementia explained.

If you're worried about your own memory or someone else's, speak to a GP. Memory problems have many causes, and some are treatable.