SHE watched as her twin disappeared into the deep pit of mental illness. No longer competing for the top grades in maths and science, he withdrew from their world and entered his own, often terrifying, parallel universe.

It took several years and a run-in with police over a stolen car to produce the diagnosis that to many is a life sentence: schizophrenia.

And while her brother struggled, Cynthia Shannon-Weickert studied.

At first, medicine seemed the ideal way to help David Shannon, who by now had been institutionalised with adult psychiatric patients.

Dr Shannon-Weickert realised that medicine was limited by the treatments that were available, and for patients with schizophrenia, these were widely recognised as less than perfect.

"I decided the best way to help was to understand what was causing the disease so that we could come up with therapies and treatments to deal with the root of the problem, rather than just treating the symptoms.

"That has been a quest that I have been on for the last 20 years."

The 43-year-old neurobiologist - formerly from the National Institute of Mental Health in the US - has just been appointed to Australia's first professorial chair of schizophrenia research, based at the Prince of Wales Medical Research Institute in Sydney.

Working with the Neuroscience Institute of Schizophrenia Research and Allied Diseases and the University of NSW, Dr Shannon-Weickert will continue her research on molecular biology and brain development as part of a NSW Government-funded five-year, $8 million research program.

Viewing the disease through the prism of a developmental disorder, she studies the molecular and cellular development in the post-mortem brains of babies, toddlers, children, adolescents, teenagers, young adults and adults and compares them to those who have schizophrenia.

"There is a developmental program that unfolds in the normal human brain as we grow, mature and come into adulthood, and what happens to the brains of people with schizophrenia is that process gets derailed, truncated or terminated.

"Those things that are part of becoming a mature adult, learning to navigate social situations, planning for our future, are the very things that people with schizophrenia cannot do."

She likens schizophrenia research to investigating a plane crash. "Before we were just looking at the debris on the ground and trying to piece together what was the cause."