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01-11-2018 | Parkinson's disease | News | Article

Dopamine to levodopa-carbidopa switch reduces impulse control disorders in PD

medwireNews: Switching from dopamine agonists to levodopa-carbidopa slow-release formulations reduces impulse control disorders (ICDs) in patients with Parkinson’s disease (PD), shows a multicentre study.

“The modified regimen also improved patients’ activities of daily living when it was successfully implemented”, say Jinwhan Cho (Sungkyunkwan University School of Medicine, Seoul, South Korea) and fellow REIN-PD investigators.

They found that 12 weeks after switching from dopamine treatment to an equivalent dose of levodopa-carbidopa, the 50 patients with ICDs achieved a significant 2.75-point average reduction in scores on the modified Minnesota Impulsive Disorders Interview (MIDI).

The patients had a high average baseline MIDI score of 9.0, ranging from 3 to 26, and the majority (66%) had two or more ICDs. The change in treatment included a 4-week individual titration period and a maintenance period of 8 weeks.

 The greatest improvements were seen for hypersexual behaviours, followed by compulsive eating, compulsive repetitive behaviours, gambling and shopping.

The improvement in impulsive control behaviours was also accompanied by a mean reduction in Unified PD Rating Scale II daily activity score of 5.27.

“Notably, neuropsychiatric traits observed in the PD-ICD patients did not change after dopamine agonist replacement”, highlights the team in the Journal of Neurology, Neurosurgery, and Psychiatry.

They do acknowledge, however, that switching from dopamine agonists was not possible for 16% of patients either because they had motor or non-motor symptoms that were sensitive to drug changes (11%) or because they developed dopamine agonist withdrawal syndrome (5%).

There was also a high dropout rate, at 32%, although the investigators suggest that “modification of anti-parkinsonian drug regimens substantially to reflect the clinical practice setting might significantly reduce the drop-out rate.”

Commenting on the findings in a related editorial, Juan Carlos Martinez-Castrillo (Hospital Ramon y

Cajal, Madrid, Spain) says that “[r]egardless of the limitation of being an open, one-arm study, some important issues emerge from this paper.”

 One of these was the identification of distinct traits when the PD patients with ICDs were compared with 60 medicated and 40 drug-naïve PD patients without ICDs at baseline.

 The behaviour characteristics of the former group consisted of anxiety, aggression and obsessive–compulsive traits.

 The researchers say that “[d]efining a risk trait of [impulsive control disorder] in PD and its manifestation during the treatment of PD will facilitate formulation of a guideline to treat such traits before and at any point after initiating PD treatment.”

 Martinez-Castrillo concludes: “ICD is a complex phenomenon in PD and this article encourages larger studies to clearly define its specific risk profile and management. Meanwhile, prevention seems to be the best strategy, as once established, ICDs are hard to reverse.”

 By Lucy Piper

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