Dementia - a brain disease that cause a long term and often gradual decrease in the ability to think and remember a persons daily functioning. Common Symptoms include emotional problems with language, decrease in motivation. A persons consciousness is usually not affected. Dementia diagnosis requires a change from a persons usual mental functioning and a greater decline than one would expect due to aging. Most common type of dementia is ALZHIEMERS. More than one type of dementia may exist in the same person. There is no cure for dementia.