She can't read books, because every time she turns a page she has already forgotten what was on it. And her life is governed by lists, reminders of what she has done and needs to do next.

They are symptoms most commonly associated with older age and dementia.

"I'm pretty forgetful," Jessica said.

"When I first got diagnosed I was sitting on the couch eating dinner and I went to the toilet and I forgot to come back.

"I thought we hadn't had dinner yet."

Ten years ago, Jessica's family were told that she probably would not live past her 16th birthday, but she defied that prediction and is facing a more hopeful future, thanks to the trial of a new drug.

The teenager is one of about 2000 people, some with terminal illnesses, receiving pioneering treatments at The Royal Melbourne Hospital's new clinical trials centre, which was launched on Wednesday.

Jessica suffers from a progressive genetic disorder – Niemann-Pick disease – which is so rare that it affects about 1 person in 100,000.

Royal Melbourne neuropsychiatrist Professor Mark Walterfang said the prognosis for children with the condition was grim.

"Usually, without treatment, people develop worsening movement to the point that they are in a wheelchair and eventually they become demented and will die," Professor Walterfang said.

But seven patients at the Royal Melbourne have been involved in an international trial of a treatment using cyclodextrin – a type of sugar – which is reportedly showing "remarkable results" in both early human trials and tests on animals.

Professor Walterfang said a trial on a colony of cats with Niemann-Pick disease in the US had seen animals that were  treated with cyclodextrin live eight-times longer than those who weren't.

He said the cyclodextrin treatment could be reversing and slowing the disease, a rarity for neurodegenerative diseases.

The drug is administered via a lumbar puncture, which requires a local anaesthetic.

Jessica, who lives in Perth, flies to Melbourne every fortnight for the treatment.

Jessica's family say that since she began taking part in the trial they have noticed she is able to take part in longer conversations.

She has recently started working twice a week at a real estate agent.

The Royal Melbourne's executive director of research, Professor Ingrid Winship, said about 2000 people per year were involved in clinical trials for conditions including kidney disease, multiple sclerosis, dementia, infectious diseases and epilepsy.

"Often the clinical trial is where you have exhausted all other opportunities," Professor Winship said.

"A lot of patients have been through everything that standard of care could offer and then something new offers this hope.

"I think that's the most important thing about clinical research trials, that it offers hope."