Merryll Vorster was testifying in the trial of Pistorius who is charged with murdering his girlfriend Reeva Steenkamp last year.
“It is my opinion, My Lady, that Mr Pistorius has an anxiety disorder,” Vorster told the court.
“They [people with anxiety disorder] work hard to control their environment to be able to alleviate their levels of anxiety.”
She said Pistorius had a strict training routine which helped him cope with his anxiety.
Pistorius prepared before he attended media functions to control his anxiety, and as he became more famous and was required to attend more public events, he had to prepare more.
“Individuals who are anxious try to bring order to their lives so they can control their environment,” she said.
Vorster evaluated the athlete and spoke to his family and friends.
The paralympic athlete shot and killed Steenkamp through the locked door of the toilet in his Pretoria home on February 14 last year. Pistorius has denied guilt, saying he thought she was an intruder about to open the door and attack him. The State contends he shot her during an argument.
Vorster said when his legs were amputated at the age of 11 months, Pistorius could not have understood what was happening to him.
She said this was a form of assault because he could not understand why he was in hospital and, because of his young age, it was difficult for his mother to comfort him.
Despite his disability, Pistorius behaved and tried to appear as normal as possible throughout his life, said Vorster.
“He was never able to allow himself to be seen as being disabled,” she said.
“Over time, this could result in increased levels of anxiety.”
She described his mother as loving and said his parents divorced when he was six. His mother drank excessively and slept with a firearm under her pillow.
“His father was an irresponsible and mostly absent parent,” she said.
The fact that Pistorius’s mother was anxious added to the children’s anxiety, the court heard. Pistorius has a younger sister, Aimee, and an older brother, Carl.
Responding to questions from Barry Roux, SC, for Pistorius, about the anxiety, Vorster said: “Well, in present situations, it clearly remained.”
Pistorius looked down as she testified.
She said he was traumatised when his mother suddenly died when he was 15.
“He was significantly traumatised by her death… He describes this as very stressful.”
Pistorius described himself as quite lonely and anxious about levels of crime in South Africa.