A district court has accepted that an elderly Ferrari driver was suffering from depression when she punched a fellow motorist in Telok Ayer Street on Feb 25, 2014, but ruled that the condition was not a contributing factor to the offence.

District Judge Chay Yuen Fatt delivered his findings yesterday, following a hearing to determine Shi Ka Yee's mental condition.

On Aug 17 last year, he convicted the 72-year-old woman of assaulting BMW driver Raphael Chong Yen Ping, 39, following a two-day trial. Mr Chong suffered a cut above his right eyebrow.

Shi's personal psychiatrist, Dr Pauline Sim Li Ping, testified in court on Wednesday that her patient was diagnosed with depression in 2009.

Dr Sim, who is a consultant psychiatrist at the Mount Elizabeth Medical Centre, said people with depression tend to react to provocation without thinking of the consequences. She said this could have been the case with Shi.

The psychiatrist said Shi felt disappointed and "taken advantage of" upon finding out that her husband was having an affair with a woman from China.

Dr Sim added that Shi often thought she was being taken advantage of because she is a woman.

"She was shocked that a BMW driver would be rude to her... that's why she reacted. It would be disastrous to incarcerate her... Treatment would be better."

Deputy Public Prosecutor Zhuo Wenzhao yesterday said Dr Sim's findings should be given very little weight.

On Wednesday, the DPP had told Judge Chay there were nine symptoms of depression according to the Diagnostic And Statistical Manual Of Mental Disorders, which is widely used by psychiatrists. These include fatigue, recurrent thoughts of suicide, insomnia and diminished interest or pleasure. DPP Zhuo also told the court that for somebody to be diagnosed with depression, a patient must display five or more of these symptoms.

Dr Sim testified on Wednesday that Shi did not display six of the nine symptoms but added that the manual was only a guide.

During the trial last year, the court heard that Shi punched Mr Chong because she felt that his BMW was blocking the way in Telok Ayer Street. He had told her: "If you don't know how to drive a Ferrari, don't drive a Ferrari."

Shi, who is represented by lawyer Irving Choh, is due to be sentenced next month. Offenders convicted of assault can be jailed for up to two years and fined up to $5,000.