[123I]?-CIT SPECT demonstrates decreased brain dopamine and serotonin transporter levels in untreated parkinsonian patients

Abstract

Striatal dopamine transporters (DATs) and serotonin transporters (SERTs) were evaluated in untreated patients with Parkinson's disease (PD) and controls using single‐photon emission computed tomography (SPECT) with 2β‐carboxymethoxy‐3β‐(4‐iodophenyl)tropane ([123I]β‐CIT). The striatal DAT specific to non‐displaceable uptake ratios of 29, and the SERT uptake measurements of 27, PD patients were compared with those of 21 and 16 controls, respectively. The results were correlated with Unified Parkinson's Disease Rating Scale (UPDRS) scores, the Hoehn & Yahr stage, age, duration of the disease, and the major PD signs. The specific DAT binding in the caudate, the putamen and the caudate/putamen ratio were measured. In all of the PD patients the striatal uptake values were bilaterally reduced, being 36.9% (P < 0.001) lower than those of the controls. In the hemiparkinsonian patients the reduction was greater on the side contralateral to the initial symptoms (33.3% vs. 27.8%) and the uptake ratios indicated a more pronounced deficit in the putamen (39.1%) than in the caudate (27.9%). The DAT uptake correlated with the UPDRS total score and activities of daily living (ADL) and motor subscores, the Hoehn & Yahr stage, and rigidity score. PD patients had significantly higher caudate to putamen ratios than the controls. In the PD patients the SERT values were lower in the thalamic and frontal regions. The SERT uptake ratio of the frontal area correlated with the UPDRS subscore I. [123I]β‐CIT SPECT provides a useful method for confirming the clinical diagnosis of PD with correlation to disease severity. Additionally, this technique allows the simultaneous measurement of SERT uptake and shows that PD patients, interestingly, seem to have decreased SERT availability in the thalamic and frontal areas. Mov. Disord. 16:124–130, 2001. © 2001 Movement Disorder Society.

Effects of acute tryptophan depletion on cognition, memory and motor performance in Parkinson's disease

“…This was the first study to use the ATD paradigm in a PD population. We hypothesized that acute lowering of TRP and thus lowering of serotonergic availability might impair memory performance, more specific secondary memory consolidation, in both populations, but might have a greater effect in the PD population since it is known that this group also shows signs of serotonergic degeneration besides the dopaminergic degeneration, even at early stages of the disease [44,45]. Based on results from preclinical data, indicating that serotonin has an inhibiting effect on the release of dopamine [13,14], we expected motor performance to improve after ATD.…”

Challenging the Serotonergic System in Parkinson Disease Patients

“…Because it is reported by Haapiniemi et al that serotonergic levels of PD patients are already lower than the levels of the healthy control subjects, one may expect a greater improvement in PD patients. 23 In addition, based on results from preclinical data, we expected an increased inhibition of striatal dopamine release by elevating the serotonergic availability. It was expected that this would result in a negative effect on aspects of motor performance in PD patients.…”

Circadian heart rate variability in Parkinson's disease

“…Because the PD process seems to involve the central nuclei as well as the peripheral autonomic ganglia and also the hypothalamus [33], the cardiovascular dysregulation may be of both central and peripheral origin.At the moment, there are no methods available for clarifying the role of the peripheral nervous system involvement in the cardiovascular autonomic dysfunction that occurs in PD. The results of the present study give further clinical support for the concept, based on pathological studies, that the pathological disease process in PD already extensively involves the autonomic centres of the CNS by the time that the clinical symptoms of PD first emerge [10].…”