Joe Biden, 81, has announced that he will not be seeking a second term as President of the United States, although he intends to stay in his role until the election later this year.

Many people have speculated that he may be suffering from age-related cognitive decline, although he has not said that this is the case.

Others are convinced that he show the typical signs of Parkinson’s disease, which affect around 153,000 people in the UK, according to the charity, Parkinson’s UK. This too has been denied by the White House.

But what are the typical features of the progressive disorder that affects the nervous system causing in many cases, difficulty with gaur and speech, as well as causing people to ‘freeze’ and lose awareness of their surroundings?

Dr Fayyaz Ahmed, a Consultant Neurologist and Honorary Senior Lecturer at Hull University Teaching Hospitals