What is Alzheimer’s disease?
Alzheimer’s disease is a brain disease that causes dementia. Alzheimer’s Society says about two out of three people living with dementia in the UK have Alzheimer’s disease.
People sometimes use “dementia” and “Alzheimer’s” as if they mean the same thing. They do not. Dementia is the name for a group of symptoms. Alzheimer’s disease is one of the diseases that causes those symptoms. See what is dementia?
The NHS says Alzheimer’s disease affects about 1 in 14 people over 65 and 1 in 6 people over 80.
What happens in the brain
The NHS explains that in Alzheimer’s disease, proteins build up in and around brain cells:
- Amyloid forms clumps called plaques around brain cells.
- Tau forms tangles inside brain cells.
This starts years before symptoms appear. Over time, brain cells are damaged and die, and parts of the brain shrink. Levels of a chemical messenger called acetylcholine also fall. Acetylcholine helps brain cells pass signals to each other.
The areas involved in memory are usually affected first. In less common forms, the areas for vision or language are affected first.
Symptoms
Alzheimer’s disease usually develops slowly over several years. Symptoms vary, but the NHS describes a general pattern.
Early symptoms
The first sign is usually minor memory problems. A person may:
- forget recent conversations or events
- misplace items
- forget the names of places and objects
- have trouble finding the right word
- ask the same questions again and again
- find it harder to make decisions or plan
- become more anxious, low or irritable
Very early problems with memory and thinking that do not yet affect daily life much may be called mild cognitive impairment. See other causes of memory loss.
Middle stage symptoms
Memory problems get worse. A person may struggle to recognise people they know. Other symptoms can include:
- increasing confusion and disorientation, such as getting lost
- problems with speech and language
- believing things that are not true (delusions) or feeling suspicious of others
- seeing or hearing things that are not there (hallucinations)
- restlessness, agitation or low mood
- needing help with everyday tasks such as washing and dressing
Later stage symptoms
In the later stage, symptoms become more severe. A person may have difficulty eating and swallowing, lose control of their bladder or bowels, gradually lose speech, and need help with most daily activities.
Risk factors
The exact cause of Alzheimer’s disease is not fully understood. The NHS lists several things that increase risk.
| Risk factor | What the NHS says |
|---|---|
| Age | The biggest risk factor. Risk doubles about every 5 years after age 65 |
| Family history | Raises risk slightly. Rare inherited forms carry a much higher risk |
| Down’s syndrome | Increases risk, because of how amyloid builds up |
| Heart and circulation health | Smoking, obesity, diabetes, high blood pressure and high cholesterol are linked to higher risk |
| Other factors | Hearing loss, untreated depression, loneliness and inactivity are also linked |
Having a risk factor does not mean someone will get Alzheimer’s disease. Many risk factors, such as smoking and inactivity, can be changed.
Getting a diagnosis
There is no single test for Alzheimer’s disease. A GP will ask about symptoms, do a physical check and arrange blood tests to rule out other causes. If Alzheimer’s disease or another dementia is still possible, the GP refers the person to a specialist memory service. The specialist may arrange more detailed memory tests and a brain scan.
NICE advises that Alzheimer’s disease should not be ruled out just because a CT or MRI scan looks normal. Read the full process on getting a diagnosis.
Treatment on the NHS
There is no cure for Alzheimer’s disease. But treatment can help with symptoms for a time.
- Acetylcholinesterase inhibitors: donepezil, galantamine and rivastigmine. NICE recommends these for mild to moderate Alzheimer’s disease.
- Memantine: NICE recommends this for severe Alzheimer’s disease, and for moderate disease if the other medicines are not suitable. It can also be considered alongside them.
- Cognitive stimulation therapy: group activities to keep the mind active. NICE recommends it for mild to moderate dementia.
See treatment for more about side effects and other approaches.
New antibody medicines
Lecanemab (Leqembi) and donanemab (Kisunla) are newer medicines. They are antibodies that help clear amyloid from the brain. They are licensed in the UK for some people with early Alzheimer’s disease.
The treatment page explains who these medicines are licensed for and the known risks.
Living with Alzheimer’s disease
Many people live well for years after diagnosis. Keeping active, staying in touch with others, and planning ahead can all help. See living well and legal and money matters.
If you care for someone with Alzheimer’s disease, see caring for someone. For support by phone, see support and helplines.