Pistorius was involved in an argument with businessman Jared Mortimer at a club in Johannesburg's upmarket Sandton business district over the weekend. Both men accuse each other of starting the altercation.
"Oscar is grappling with an extreme level of emotional pain that is manifesting itself in some of his recent unwise actions and choices," Pistorius' uncle Leo said in a statement.
"Those of us closest to him have been witness to his escalating sense of loneliness and alienation. This, we believe, is underlying some of his self-harming behaviour."
The athlete, known as "Blade Runner" because of the carbon-fibre prosthetic running legs he uses, is on trial for the murder of his girlfriend, Reeva Steenkamp, whom he shot and killed at his luxury Pretoria home on Valentine's Day last year.
Pistorius says he killed Steenkamp after mistaking her for an intruder hiding in the toilet next to his bedroom. The state accuses him of shooting her in cold blood after an argument.
His lawyers wrapped up their defence last week and the case was adjourned until Aug. 7 to allow the legal teams to prepare closing arguments.
(Reporting by Olivia Kumwenda-Mtambo; Editing by Ed Cropley)
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