CBD is corticobasal degeneration or also known as a corticobasal syndrome. It has many of the same signs and symptoms of PSP, which is why it is often very difficult to diagnose. It is also quite closely related to another neurological condition called MSA, multisystem atrophy. As time goes on, sometimes it is easier to get a diagnosis because some of the signs and symptoms are very much the same. One of the main characteristics with CBD is people have a jerky movement and often one arm will have a life of its own, which we call ‘alien limb syndrome’. Often the arm will just raise up without the person being aware of it. It will often do odd things on its own like a dip into people’s pockets, which can often lead with some difficulties with carers because the arm may be touching them when the person is not aware it is doing so. So the main symptoms are very much the same as PSP. There appears to be an overlap. PSP itself is a rare condition. CBD is an even rarer condition, but some people have the rarest form when they have an overlap.