A new study from the University of Hertfordshire, published in the journal PLOS ONE, has found that urinary dysfunction and incontinence observed among Parkinson's disease sufferers may start at the level of bladder and not exclusively from the disorder of brain function, as was previously assumed.
The findings have important implications for the treatment of urinary incontinence in Parkinson's disease and may lead to the development of more targeted therapies in the future.
The study was conducted by Dr Mahmoud Iravani at the University of Hertfordshire, together with collaborators at the Neurodegenerative Disease Research Group at King's College London and the World renowned expert in the field of non-motor Parkinson's disease, Prof K. Ray Chaudhuri at King's Health Partnership, King's College Hospital.
For the first time, researchers compared non-Parkinsonian bladder muscles with those in a human relevant model of Parkinson's, in which all nerve input was severed so that there was no influence of the brain on the function of the bladder. Despite this, tissues devoid of any nerve input produced greater contraction than those from the non-parkinsonian models.
The findings suggest that loss of dopamine in the brain may cause long term changes at the level of the bladder altering its functionality, meaning that alternative approaches to treatments may be required. Currently this symptom is poorly treated and the drugs used to treat the disease often worsen urinary incontinence.
Dr Mahmoud Iravani, Lead Author from the University of Hertfordshire, said: "Although Parkinson's disease is often associated with slowness of movement, limb tremor and loss of balance, there are many other features of the disease, such as urinary incontinence, which adversely affect the quality of life for Parkinson's sufferers. Currently the drugs used to treat the disease often worsen urinary incontinence, meaning additional suffering for patients with Parkinson's.
For many years it was assumed that loss of the chemical messenger dopamine - which leads to the motor symptoms of Parkinson's disease - also causes the non-motor symptoms. However our research has found that this is not necessarily the case, and that incontinence may actually start at bladder level."
"Currently, treatment of urinary incontinence is one of the top ten overarching research priorities in Parkinson's disease according Parkinson's UK. This finding has important implications for the future development of more targeted and effective therapies for this condition."
It is hoped that the University of Hertfordshire will extend this work further and will become one of the premier centres for research into non-motor aspects of Parkinson's disease.
Article: Altered detrusor contractility in MPTP-treated common marmosets with bladder hyperreflexia, Sara Pritchard, Michael J. Jackson, Atsuko Hikima, Lisa Lione, Christopher D. Benham, K. Ray Chaudhuri, Sarah Rose, Peter Jenner, Mahmoud M. Iravani, PLOS ONE, doi: 10.1371/journal.pone.0175797, published 17 May 2017.