Striatal dopamine transporter abnormalities in patients with essential tremor

Background and methods We used I-123- loflupane SPECT to study 32 unrelated patients with essential tremor (16 with positive familial history), 47 sporadic tremor dominant patients with Parkinson's disease and 31 healthy control subjects. Discriminant analysis was used to categorize healthy subjects and patients with Parkinson's disease or essential tremor. Results Patients with essential tremor had higher uptake values (50% putamen and 21% caudate, P<0.001) compared to those with Parkinson's disease but lower than healthy subjects (15% putamen and 21 % caudate, P<0.05). Discriminant analysis classified seven essential tremor patients in the healthy subjects cohort (22%) and two as Parkinson's disease (6%). Conclusions Our results show that some essential tremor patients may present mild abnormalities of striatal dopamine transporters and a typical Parkinson's disease-like pattern of uptake loss. These findings suggest a link between the two disorders.