 |
This figure does not vary significantly from one country to another, although the number of cases reported by different countries are influenced by the stage of development of medical services in different countries and by varying medical priorities. The average age of death is 67 and death rates are highest for people in their 70s. Equal numbers of men and women are affected and 98% of deaths occur in people over 45 years old. Similar to Alzheimer's disease, approximately 10% of CJD cases are familial, i.e. inherited. A number of mutations in the human PrP gene are known to give rise to inherited forms of CJD - two of these are known as familial fatal insomnia (FFI) and Gerstmann-Straussler-Scheinker disease (GSS). These diseases are relatively easy to recognise since many members of the same family are affected. |
In the early stages, it is relatively easy to confuse CJD for a wide variety of other conditions which affect the brain. A number of medical tests are commonly used to try to confirm a diagnosis of CJD. A small amount of the fluid which surrounds the brain and spinal cord may be taken by lumbar puncture and tested to ensure there is no infection of the brain which may be causing the symptoms. CT or "CAT" scans are a specialised form of X-rays used to examine the shape of the brain, although they cannot see the "spongy" changes characteristic of CJD directly. MRI scans (magnetic resonance imaging) are an alternative way of looking at the brain without using X-rays. Electroencephalograms (EEG) record the electrical activity of the brain - in most cases of CJD there are characteristic disturbances of the brainwave pattern which can help to confirm the diagnosis. In spite of all of this, the only certain way in which a diagnosis of CJD can be confirmed is to examine the brain microscopically after death.
