This is a progressive condition in which nerve cells in the brain are affected by a process which causes alteration in the brain chemistry and the size of the brain substance shrinks. This disease is the single most common cause of dementia. The disease process progresses which in most cases, means several years of intellectual and personal decline, which gets worst as time passes.

The cause of the disease is unknown. The onset is rare before the age of sixty, but thereafter increases steadily with age.

The symptoms and signs vary between individuals, but there are three broad areas. At first, the person becomes increasingly forgetful and may try to cover-up by writing lists, or seeking the help of others. The problem when associated with dementia may cause the sufferer to become anxious and depressed. Another phase is when the person suffers memory loss of events. The person with dementia will be able to recall long ago events, like school days, however; they may forget what they had for breakfast the previous morning. They will also lose touch with time and may not be able to tell what day, month or year it is. They can lose their way around their homes and are not able to find the right words when they need to explain themselves. They suffer personality changes, and you may become surprised at their behaviour they may become aggressive, demanding, unpleasant and violent.

The person often refers to seeing objects that are not really there, and this becomes more evident at night. They may later begin to neglect their personal hygiene (bathing and changing clothes) and also become incontinent (of urine and faeces).

It is important at the beginning of these symptoms that a doctor sees the person so that the condition is properly diagnosed and treatment may be carried out.