Qld school stabber had depression: court

A teenager's mental illness and developmental disorder partly explains why he took a knife to his Brisbane school and tried to kill a classmate, a court has heard.

The 16-year-old is facing up to 10 years' detention over the 2013 school stabbing, for which he was found guilty of attempted murder.

The victim, a Year 10 boy, suffered only minor injuries - despite being stabbed in the neck - because the blade didn't pierce any vital structures.

The pair had clashed the previous day when the victim tried to steal lollies from the other boy, a trial earlier this year heard.

The teen, who has Aspergers Syndrome, hid a knife in his school blazer the following morning and said he wanted to prevent the other boy from turning out like his violent stepfather.

At a Brisbane court hearing, defence barrister Rob East said pre-sentence doctors' reports shed light on the boy's motive.

"It is clear that what may have appeared to have been a relatively trivial matter to most young boys had a particular significance to (the defendant) because of his major depression, because of his Aspergers Syndrome," Mr East told the Brisbane Supreme Court.

He said according to one doctor it lead to "black-and-white thinking".

"In his (the teen's) mind, he came to the plainly irrational view - but nonetheless the view - that the complainant was going to turn out like the man that he had lived with."

The teenager listened from the open dock where he sat in a far end seat so he could be next to his parents.

He is facing a maximum sentence of 10 years with the possibility of being transferred to an adult prison once he turns 17.

Crown prosecutor Sarah Farnden said the judge had the option of combining detention with probation.

The hearing before Justice Jean Dalton continues.