Dr Isobel Campbell also said that James Dunleavy, 40, grinned when asked about the death of his sister.
Dr Campbell was the third psychiatrist to give evidence at the High Court in Edinburgh yesterday. All three said Dunleavy presented them with a puzzle because he would not talk about his mother's death.
They agreed Dunleavy had a serious problem, but could not say exactly what.
In her report Dr Campbell said: "He has displayed poor anger management and problem solving but this would not necessarily be indicative of mental illness."
Dunleavy, also known as Seamus Dunleavy, denies battering to death mother Philomena, 66, of Marino, Dublin between April 30 and May 7 last year, and burying her body parts just 15 minutes' walk from his flat.
The trial continues.