The term 'dementia' is used to describe the symptoms that occur when the brain is affected by specific diseases and conditions.
Symptoms of dementia include loss of memory, confusion and problems with speech and understanding.
Dementia is progressive, which means the symptoms will gradually get worse.
For more information about dementia visit the Alzheimer's society website.
More top news
Nigel Farage told ITV Tonight the 45th president will boost Britain as he identified the one thing Trump must do in power to be a success.
Dan Evans has caused another shock at the Australian Open by beating Bernard Tomic to reach the last 16.
Fighters blew up Palmyra's Tetrapylon and the facade of its Roman Theatre, according to Syrian antiquities chief Maamoun Abdulkarim.