Reduced dopamine transporter binding in patients with juvenile myoclonic epilepsy

Background: Behavioral and cognitive problems are frequently encountered in juvenile myoclonic epilepsy (JME). The underlying mechanisms are unknown. Based on previous data showing that the dopamine system is involved in motor as well as cognitive functions, we tested whether JME may be associated with changes in this system, and if such changes are linked to interictal dysfunctions in these patients. Method: PET and [(11)C] PE2I was used to investigate the regional binding potential to the dopamine transporter (DAT) in 12 patients with JME and 12 healthy controls. Binding potential was calculated in the midbrain, substantia nigra, caudate, and putamen. We also tested possible correlations between the respective measures and performance in several neuropsychological tests. Results: Patients had a reduced binding potential in the substantia nigra and midbrain (p = 0.009 and 0.007), and normal values in the caudate and putamen. They also exhibited impaired psychomotor speed and motor function, which in some tests correlated with DAT binding potential in the midbrain. Conclusion: Dopamine signaling seems impaired in the target regions for dopaminergic neurons (the striatum and frontal lobe), and related to several interictal dysfunctions in JME. The findings add a new aspect to the pathophysiology of JME.