In the later stages of dementia, the person affected will have problems carrying out everyday tasks and will become more and more dependent on other people.
Becoming forgetful does not necessarily mean that you have dementia. Memory loss can be an effect of ageing, and can also be a sign of stress or depression. If you are worried about yourself, or someone close to you, it is worth discussing your concerns with your GP. It is very important to get a proper diagnosis.
The following links below offer more detailed information and advice on a wide range of mental health conditions:
Age UK
MIND
Royal College of Psychiatrists
The Mental Health Foundation
NHS Choices