The standard treatments for Parkinson's disease, which work by increasing dopamine signalling in the brain, can trigger highly risky behaviours, known as 'impulsive-compulsive spectrum behaviours' (ICBs) in approximately 5-10% of patients.
New results, published today in the journal Neuropsychopharmacology, uncover a possible explanation for this behaviour – impaired self-control combined with surprisingly normal motivation. Researchers have shown that Parkinson's patients with ICBs are much more willing to take immediate but smaller benefits rather than waiting for larger ones in the future.
"Some patients end up gambling away their life savings while others run up huge credit card debts. This work sheds light on the reasons behind such behaviours, and may help to treat sufferers of Parkinson's disease in the future," said Charlotte Housden who carried out the work at UCL's Institute of Cognitive Neuroscience, and is now at the University of Cambridge.
Researchers studied a group of 36 Parkinson's disease patients, half of whom had ICBs, and compared them to a group of 20 elderly volunteers without Parkinson's disease. All the participants completed two tests: a computer game that measured motivation, on which the participants attempted to win cash by responding quickly and learning associations between pictures and money; and a questionnaire about financial decisions.
This questionnaire measured a form of impulsivity called "delay discounting", by asking whether someone would prefer receiving a smaller payment quickly, as opposed to waiting for a larger payment. For example, would you prefer to receive £50 today or £80 in a month's time?
The data revealed a clear pattern of results. Against the researchers' expectations, the Parkinson's patients who suffered from ICBs were not more motivated to win money on the computer game than the control volunteers. They were also no better at learning about which stimuli predicted money. On the other hand, they were considerably more likely to choose smaller immediate payments over larger but delayed ones on the questionnaire.
Dr Jonathan Roiser, from the UCL Institute for Cognitive Neuroscience, and supervisor of the study said: "The pattern of more impulsive choices together with intact motivation and learning suggests that ICBs may be mediated by impaired self-control, and not excessive motivation for rewards."
The researchers hope that this study might help in the identification and treatment of ICBs in the future.
Charlotte Housden explained: "Often, when neurologists identify these risky behaviours, their only option is to reduce the dose of drugs which treat the primary symptoms of Parkinson's disease, such as tremor and stiffness. However, this is far from ideal, since an inevitable consequence of this strategy is that these primary symptoms get worse. Our results suggest that treating impulsivity in Parkinson's disease patients with ICBs, for example with drugs used to treat other types of impulsive behaviours, might reduce their risky behaviours without worsening their primary symptoms."
Notes for Editors
1. For more information or to interview Charlotte Housden, please contact Clare Ryan in the UCL Media Relations Office on tel: +44 (0)20 7679 9726, mobile: +44 07747 565 056, out of hours +44 (0)7917 271 364, e-mail: email@example.com.
2. ''Intact Reward Learning but Elevated Delay Discounting inParkinson's Disease Patients With Impulsive-Compulsive Spectrum Behaviors' is published in Neuropsychopharmacology. Journalists can obtain copies of the paper by contacting UCL Media Relations.
Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender, and the first to provide systematic teaching of law, architecture and medicine. UCL is the fourth-ranked university in the 2009 THES-QS World University Rankings. UCL alumni include Marie Stopes, Jonathan Dimbleby, Lord Woolf, Alexander Graham Bell, and members of the band Coldplay. UCL currently has over 12,000 undergraduate and 8,000 postgraduate students. Its annual income is over £600 million.
Clare Ryan | EurekAlert!
Millions through license revenues
27.04.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn
New High-Performance Center Translational Medical Engineering
26.04.2017 | Fraunhofer ITEM
More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.
Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...
Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.
"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
28.04.2017 | Event News
20.04.2017 | Event News
18.04.2017 | Event News
28.04.2017 | Medical Engineering
28.04.2017 | Earth Sciences
28.04.2017 | Life Sciences