Dementia is not a disease itself. It's a collection of symptoms that result from damage to the brain caused by different diseases, such as Alzheimer's. These symptoms vary according to the part of the brain that is damaged.

Common early symptoms of dementia
Different types of dementia can affect people differently, and everyone will experience symptoms in their own way.

However, there are some common early symptoms that may appear some time before a diagnosis of dementia. These include:

memory loss
difficulty concentrating
finding it hard to carry out familiar daily tasks
struggling to follow a conversation or find the right word
being confused about time and place
mood changes

These symptoms are often mild and may get worse only very gradually. It's often termed "mild cognitive impairment" (MCI) as the symptoms are not severe enough to be diagnosed as dementia.

You might not notice these symptoms if you have them, and family and friends may not notice or take them seriously for some time. In some people, these symptoms will remain the same and not worsen. But some people with MCI will go on to develop dementia.

Symptoms in the later stages of dementia
As dementia progresses, memory loss and difficulties with communication often become severe. In the later stages, the person is likely to neglect their own health, and require constant care and attention.

The most common symptoms of advanced dementia include:

memory problems – people may not recognise close family and friends, or remember where they live or where they are
communication problems – some people may eventually lose the ability to speak altogether. Using non-verbal means of communication, such as facial expressions, touch and gestures, can help
mobility problems – many people become less able to move about unaided. Some may eventually become unable to walk and require a wheelchair or be confined to bed
behavioural problems – a significant number of people will develop what are known as "behavioural and psychological symptoms of dementia". These may include increased agitation, depressive symptoms, anxiety, wandering, aggression, or sometimes hallucinations
bladder incontinence is common in the later stages of dementia, and some people will also experience bowel incontinence