We describe a 73-year-old female patient with
Parkinson disease who developed
impulse control disorders (ICDs) and
dopamine dysregulation syndrome (DDS) owing to
piribedil overdose. She was initially put on
piribedil 150 mg; and owing to
disease progression,
levodopa was added 4 years later. Three years later,
piribedil was raised to 200 mg; but presumably owing to a misunderstanding, she took 400 mg/d, which was well tolerated and produced an improvement in her parkinsonian symptoms.However, over the next few weeks, she started shopping compulsively, buying unnecessary clothes and food. In addition, she visited her dog's veterinarian several times a day with nonsense queries. She began to have financial problems and family disruption. During an examination, mild
dyskinesia was evident.We diagnosed ICDs and most likely
dopamine dysregulation syndrome DDS.
Piribedil doses were decreased to 200 mg/d and
levodopa increased up to 750 mg/d, with a clear improvement in compulsive behavior without worsening of the
dyskinesia.Our case shows that even in cases in which regular doses of
dopamine agonists are harmless, dose increments can induce these unwanted effects.