Pick's disease is a progressive dementia commencing in middle life, usually between 50 and 60 years of age (although it has been diagnosed in people from the ages of 20 to 80). This is earlier than is common in Alzheimer's Disease. It results in slowly progressing changes in character and social deterioration leading to impairment of intellect, memory and language. Where Alzheimer's Disease generally affects most of the brain, this disease affects specific areas of the brain - the frontal and temporal lobes. Abnormal cells develop in this part of the brain (called Pick's cells, after the discoverer of the condition, Arnold Pick). These can only be identified by post-mortem examination of the brain.

In the early stages of the disease, the person usually remains aware of time and is able to recognise people and places unlike the usual presentation of Alzheimer's Disease. Mathematical skills are usually relatively well preserved. However, failure to recognise faces and using objects wrongly sometimes occurs.

The disease can result in personality change and obsessive and compulsive behaviours. A loss of mental flexibility means that they become unable to see someone else's point of view. It is not uncommon for the person to become aggressive or rude in a way which is quite out of character. They may talk to strangers, make inappropriate comments in public, and lack normal sexual inhibitions. Speech problems are common and range from a reduction in the quantity or quality of speech in some people to total loss of speech in others. Echoing what has just been said is a fairly common symptom.

Pick's disease affects men and women alike. It does exist as a genetic disease [autosomal dominant] in some families, but, as in Alzheimer's Disease, this is rare. The rate of progression varies enormously ranging from a duration of less than 2 years to well over 10 years. The disease progresses through early stages of disturbing changes in judgement and behaviour, through the development of more marked symptoms (such as loss of speech and obsessional behaviour) to a generalised dementia.