Rebekah Lawrence jumped to her death from a Sydney office building while in a psychotic "child-like" state brought on during a self-help course she attended days earlier, an inquest has been told.
Forensic psychiatrist Dr Michael Diamond told the inquest the use of childhood regression therapies in the type of course Ms Lawrence had attended was "risky" and "reckless".
Ms Lawrence plunged to her death from the second storey of the Macquarie Street building shortly before 7pm on December 20, 2005.
An autopsy found the 34-year-old had no drugs or alcohol in her system when she died, two days after completing a Turning Point course described as a "journey to the core of the human spirit".
An inquest into her death at Glebe Coroner's Court is investigating whether the self-help course was in any way to blame for the psychosis that prompted her to jump.
Forensic psychiatrist Michael Diamond told the inquest today that the psychotic state Ms Lawrence was in when she jumped was brought about by her participation in an "intrinsically unsafe" course.
People who observed Ms Lawrence just prior to her death gave a very clear description of a person displaying regressed, child-like behaviour, he said.
"The petulant behaviour, the sing-song voice, the taking off her clothes, the coquettishness, the child-like voice ... these are clear descriptions of regressive behaviour," Dr Diamond said.
"It was something that was actually participated in during the course, so it's difficult not to see a causal link."
Regression sessions were a normal and good part of therapy, but they must happen in a safe, trusting environment, Dr Diamond said.
"It's now common knowledge that attempts to do this in short, sharp, controlled (sessions, or those) targeting regression as the desired effect in an environment where there are none of the real supports or capacities to deal with it is a dangerous thing," he said.
"And that's why using these powerful techniques in quite a risky way or even a reckless way is really not encouraged."
Dr Diamond said he had collated considerable material from family, friends, co-workers and even a counsellor of Ms Lawrence's, and there was no indication she suffered from any pre-existing mental condition before she undertook the course.
"My conclusion is that there were experiences that she was exposed to which had a direct causal link to the development of psychosis," he said.
"There was nothing in her background that would suggest a psychotic episode but for the psychological experiences in the course she attended.
"Having been exposed to an environment where she was talking through an evocative regression, it played a significant part in developing the psychosis."
The inquest before Deputy State Coroner Malcolm MacPherson continues.