A former boxer accused of attempting to murder a 14-year-old girl suffered brain damage in a road crash five years earlier, a court heard.

David Waterhouse, 51, denies deliberately stabbing the teenager in the chest in Holme Wood, Bradford. She lost more than four pints of blood after he pierced her diaphragm and liver with a kitchen knife.

Waterhouse, an administrator with the Department of Work and Pensions, claims he was not responsible for his actions when he injured the girl on June 29, 2006. He pleads not guilty to attempted murder and an alternative charge of wounding with intent to cause grievous bodily harm.

A jury at Bradford Crown Court heard that Waterhouse told police he charged past the girl with two knives and did not realise he had stabbed her. He told detectives: "My head was all over".

Waterhouse said he drank six vodkas and a can of beer that afternoon. He said he suffered from epilepsy and blackouts and had two operations to remove blood clots from his head, the jury was told.

In 2001, he was in a road accident that left the frontal lobes of his brain damaged.

Waterhouse, a father of four of no fixed address, said he threw the knife down by an alleyway.

He told officers he was angry about people selling drugs on the Holme Wood Estate.

After the stabbing, Waterhouse is alleged to have used his mobile phone to text his former partner: "Six more to finish."

The girl, who cannot be named for legal reasons, needed emergency surgery at Bradford Royal Infirmary.

The trial continues.