London, Aug 10 (IANS): A drug which has already been in use to treat liver disease could be an effective treatment to slow the progression of Parkinson's disease, new research has found.

The study could pave the way for early clinical trials of the drug ursodeoxycholic acid (UDCA) in Parkinson's patients.

"UDCA has been in clinical use for decades and thus could be advanced to the clinic rapidly if it proves beneficial in clinical trials," said one of the researchers Oliver Bandmann, professor at the University of Sheffield in England.

A mutation in the LRRK2 gene is the single most common inherited cause of Parkinson's disease.

However, the precise mechanism that leads to Parkinson's is still unclear.

Defects in mitochondria - known as the powerhouse of the cell -- and as a consequence reduced energy levels, are a factor in a number of diseases that affect the nervous system including Parkinson's.

Nerve cells have a particularly high energy demand, therefore defects in the cell's energy generators will crucially affect their survival.

"We demonstrated the beneficial effects of UDCA in the tissue of LRRK2 carriers with Parkinson's disease as well as currently asymptomatic LRRK2 carriers. In both cases, UDCA improved mitochondrial function as demonstrated by the increase in oxygen consumption and cellular energy levels," Heather Mortiboy from the University of Sheffield explained.

"Following on from the promising results of our in vitro drug screen, we were keen to further investigate and confirm the potential of UDCA in vivo - in a living organism,” Bandmann said.

In fruit flies, the mitochondrial defects caused by the LRRK2 mutation to brain cells can be monitored through the progressive loss of visual function.

Flies carrying the mutation maintained their visual response when fed with UDCA, showing the potential of the drug as a novel therapy for Parkinson's.

The findings were detailed in the journal Neurology