Striatal dopamine transporter and extrapyramidal symptoms in frontotemporal dementia

To evaluate dopaminergic function in patients with frontotemporal dementia (FTD).

Patients with FTD not only show typical behavioral and cognitive deficits but extrapyramidal symptoms, most commonly rigidity and akinesia. The pathophysiologic basis of these symptoms is unclear.

The authors investigated 12 patients (mean age = 67.2 +/- 7.2 years, range = 52 to 76 years) with FTD using a cocaine analogue [11C]CFT as a ligand with PET. The results were compared with those of 15 healthy control subjects (mean age = 49.7 years, range = 23 to 70 years) using analysis of covariance to adjust for difference in age. A dynamic 80-minute study was performed, and (region - cerebellum)/cerebellum ratios were calculated for the caudate nucleus and putamen. The severity of extrapyramidal symptoms was evaluated by the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS).

The mean age-adjusted [11C]CFT uptake value in the putamen in patients with FTD was reduced to 82% of the control value (p = 0.017), with the corresponding figure for caudate [11C]CFT uptake being 86% (p = 0.007). The motor UPDRS scores of patients with FTD showed a negative correlation with [11C]CFT uptake in both the putamen (r = -0.76, p = 0.004) and caudate nucleus (r = -0.70, p = 0.01).

Nigrostriatal dopaminergic function is impaired in FTD, with the projections to the putamen and caudate nucleus being affected to the same degree. The reduction in the binding of the dopamine transporter ligand [11C]CFT is related to the severity of extrapyramidal symptoms of the patients.