This is the heartbreaking moment that a US Army veteran with dementia cannot remember his son's name.

Kenneth Keene Sr, 70, from Philadelphia, who was diagnosed with dementia in 2014, is filmed by his son as they have a conversation while in the car.

But a smiling Mr Keene, while able to say his own name, repeatedly calls his son 'John' when asked.

This is the heartbreaking moment that a US Army veteran with dementia cannot remember his son's name. Kenneth Keene Sr, 70, from Philadelphia, who was diagnosed with dementia in 2014, is filmed by his son as they have a conversation while in the car

The clip is part of a series of Youtube videos produced by the younger Mr Keene, 47, entitled 'The Journey with ToughKenaMan', documenting his father's disease.

The video starts with the 70-year-old saying to his son, 'do you know who I am?'

When Mr Keene Jr replies, 'you're ToughKenaMan,' his father laughs endearingly and repeats the nickname.

He then says: 'I'm Kenneth Keene and I'm tough KenaMan.'

But when his son says, 'do you know who I am?', Mr Keene can only laugh before saying: 'I don't know exactly but I can see ya, I know ya.'

Mr Keene Jr replies, 'Yeah? Who am I?' but his father does not know and says 'John'.

But a smiling Mr Keene, while able to say his own name, repeatedly calls his son 'John' when asked. The clip is part of a series of Youtube videos produced by the younger Mr Keene, 47, entitled 'The Journey with ToughKenaMan', documenting his father's disease

'No, I'm not John,' Mr Keene Jr replies, before asking the question again.

Mr Keene Sr gives the same answer before laughing again and looking across at his son.

He continues to push his father to try to remember his name, but Mr Keene Sr is unable to and instead suggests 'John' again when he has a third go.

But finally, when his Mr Keene Jr says, 'Who is John?' his father replies, 'I'm Kenneth Keene and you are Kenneth Keene'.

Mr Keene Jr keeps asking his father what his name is. After saying 'John' a few more times, Mr Keene Sr eventually gets it right and says, 'I'm Kenneth Keene and you are Kenneth Keene'

Mr Keene Jr describes his Youtube channel as a 'son's effort to raise awareness and share real life experiences with the world while his while his Father, U.S. Army veteran Kenneth Keene Sr. enters deeper into the many different stages of Frontotemporal lobe dementia.'

Mr Keene Jr started filming his father doing everyday things as a way of documenting what it is like to be around someone who has the disease.

He told the Philadelphia Inquirer in 2017 that he spends three to five hours at a time with his father once a week.