Overview
Alzheimer's disease is the most common cause of dementia, accounting for 60–80% of cases. It is a progressive neurological disorder that causes brain cells to degenerate and die, resulting in a continuous decline in thinking, behavioural, and social skills that disrupts the ability to function independently. While most people with Alzheimer's are over 65, early-onset Alzheimer's can affect people in their 40s and 50s.
Causes and risk factors
The following factors are associated with the development of Alzheimer's Disease:
- Accumulation of amyloid plaques and tau tangles in brain
- Genetic factors: APOE-e4 gene, rare familial mutations
- Age — greatest known risk factor
- Family history of dementia
- Down's syndrome (trisomy 21)
- Previous severe head injury
- Cardiovascular disease risk factors
- Chronic poor sleep
- Limited mental and social engagement
- Depression (possible risk factor)
Signs and symptoms
Common signs and symptoms of Alzheimer's Disease include:
- Memory loss affecting daily life, particularly recent events
- Difficulty planning or solving problems
- Confusion with time or place
- Problems with words in speaking or writing
- Losing things and inability to retrace steps
- Poor judgement and decision-making
- Withdrawal from social activities
- Personality and mood changes
- Difficulty completing familiar tasks
- In late stages: loss of speech, mobility, and continence
Diagnosis
Alzheimer's Disease is typically diagnosed through a combination of medical history, physical examination, and appropriate investigations such as blood tests, imaging, or specialist review, depending on the specific condition and presentation. Your doctor will consider all relevant symptoms and risk factors before making a diagnosis.
Treatment options
Treatment approaches for Alzheimer's Disease may include:
- No cure currently available
- Acetylcholinesterase inhibitors (donepezil, rivastigmine, galantamine) for mild to moderate
- Memantine for moderate to severe stages
- Lecanemab and donanemab — new amyloid-targeting drugs showing some benefit in early stages
- Non-pharmacological approaches: cognitive stimulation, reminiscence therapy
- Carer support and education
- Management of behavioural symptoms
- Advance care planning
Prevention
Evidence supports: regular physical and mental exercise, Mediterranean diet, social engagement, treating cardiovascular risk factors, adequate sleep, and not smoking.
Complications
If left untreated or poorly managed, Alzheimer's Disease can lead to complications including:
Total loss of independence, need for full-time care, complications including aspiration pneumonia, pressure sores, malnutrition, and death.
Sources and references: This article is written in accordance with NHS UK, WHO, and Mayo Clinic clinical guidelines. It is reviewed for accuracy by the SymptomSense content team. ICD-10 code: G30. Last reviewed June 2026.