`Double amputee` Pistorius has been greatly affected by his disability

London: A sports doctor told Paralympic runner Oscar Pistorius` murder trial that the double amputee has been greatly affected by his disability.

Defence witness Wayne Derman told the court that Pistorius suffered significant stress and anxiety. According to the BBC, Pistorius claims that he shot his girlfriend Reeva Steenkamp on Valentine`s Day last year after mistaking her for an intruder in their house. The prosecution argues that the athlete killed her deliberately after a row. On Monday, the court heard Pistorius was not suffering from a mental disorder when he shot Steenkamp and according to a psychiatrists` report the Paralympic runner is capable of distinguishing between right and wrong and so should bear criminal responsibility for his actions. Pistorius` murder trial also heard a psychologist`s assessment on Wednesday, which found that the double amputee had post-traumatic stress disorder since the shooting and could be a suicide risk.