Progressive loss of raphe nuclei serotonin transporter in early Parkinson's disease: A longitudinal (123)I-FP-CIT SPECT study.

Serotonergic raphe nuclei dysfunction has been documented in Parkinson's disease, both in pathological and neuroimaging studies, and has been associated with scores of tremor and non-motor symptoms. However, no in vivo longitudinal investigations have been conducted to assess the rate of decline of raphe serotonin transporter availability in the early stages of the disease. To measure the rate of decline of raphe serotonin transporter availability over a two-year interval in patients with recently diagnosed disease and its association with non-motor symptoms over time. Baseline and two-year follow-up 123ioflupane-fluoropropyl-carbomethoxy-3-beta-4-iodo-phenyltropane (123I-FP-CIT) SPECT scans of 173 early Parkinson's disease patients enrolled in the Parkinson's Progressive Markers Initiative were analysed and non-motor symptoms scores recorded. A 16.6 ± 20.9% (mean ± SD) reduction in raphe serotonin transporter availability was found from baseline to two-year follow-up in the entire cohort. No differences in progression were found between tremor dominant and postural instability/gait difficulty phenotypes. At follow-up 34.1% of patients showed a moderate-to-severe reduction of raphe serotonin transporter availability with respect to the controls' mean. We did not find any significant correlation between raphe serotonin transporter availability and scores of depression, excessive daytime sleepiness and REM sleep behaviour disorder. 123I-FP-CIT SPECT was able to measure longitudinal reductions in raphe serotonin transporter availability in the early phases of Parkinson's disease. About four years after diagnosis, raphe serotonin transporter availability was significantly reduced in more than one third of the population, but does not appear to be correlated to non-motor symptoms at this stage.

Pasquini J ，Ceravolo R ，Brooks DJ ，Bonuccelli U ，Pavese N ... -  《-》

Clinical correlates of raphe serotonergic dysfunction in early Parkinson's disease.

Post-mortem and neuroimaging studies suggest that the serotonergic system, which originates from the brainstem raphe nuclei, is disrupted in Parkinson's disease. This could contribute to the occurrence of non-motor symptoms and tremor, which are only partially explained by dopamine loss. However, the level of involvement of the serotonergic raphe nuclei in early Parkinson's disease is still debated. (123)I-FP-CIT single photon emission computed tomography is a marker of dopamine and serotonin transporter availability. While (123)I-FP-CIT binds primarily to dopamine transporters in the striatum, its binding in the brainstem raphe nuclei reflects serotonin transporter availability. We interrogated baseline single photon emission computed tomography scans of subjects recruited by the Parkinson's Progression Markers Initiative to determine: (i) the integrity of the brainstem raphe nuclei in early Parkinson's disease; and (ii) whether raphe serotonin transporter levels correlate with severity of tremor and symptoms of fatigue, depression, and sleep disturbance. Three hundred and forty-five patients with early drug-naïve Parkinson's disease, 185 healthy controls, and 56 subjects with possible Parkinson's disease without evidence of dopaminergic deficit were included. In the Parkinson's disease cohort, 37 patients had a tremulous, 106 patients had a pure akinetic-rigid, and 202 had a mixed phenotype. Patients with Parkinson's disease had significantly lower serotonin transporter availability in the brainstem raphe nuclei compared to controls (P < 0.01) and subjects without evidence of dopaminergic deficit (P < 0.05). However, only 13% of patients with Parkinson's disease individually had reduced signals. Raphe serotonin transporter availability over the entire Parkinson's disease cohort were associated with rest tremor amplitude (β = -0.106, P < 0.05), rest tremor constancy (β = -0.109, P < 0.05), and index of rest tremor severity (β = -0.104, P < 0.05). The tremulous Parkinson's disease subgroup had significantly lower raphe serotonin transporter availability but less severe striatal dopaminergic deficits compared to akinetic-rigid patients with no resting tremor (P < 0.05). In tremulous patients, raphe serotonin transporter availability was also associated with rest tremor constancy (β = -0.380, P < 0.05) and index of rest tremor severity (β = -0.322, P < 0.05). There was no association between raphe serotonin transporter availability and fatigue, depression, excessive daytime sleepiness, or rapid eye movement sleep behaviour disorder in early Parkinson's disease. We conclude that the raphe nuclei are affected in a subgroup of early drug-naïve Parkinson's disease patients and that reduced raphe serotonin transporter availability is associated with the severity of resting tremor but not non-motor symptoms.

Qamhawi Z ，Towey D ，Shah B ，Pagano G ，Seibyl J ，Marek K ，Borghammer P ，Brooks DJ ，Pavese N ... -  《-》

Progression of tremor in early stages of Parkinson's disease: a clinical and neuroimaging study.

Pasquini J ，Ceravolo R ，Qamhawi Z ，Lee JY ，Deuschl G ，Brooks DJ ，Bonuccelli U ，Pavese N ... -  《-》

Striatal DAT and extrastriatal SERT binding in early-stage Parkinson's disease and dementia with Lewy bodies, compared with healthy controls: An (123)I-FP-CIT SPECT study.

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are thought to be part of a spectrum: both have a clinical profile including symptoms associated with dopaminergic and serotonergic loss, yet few imaging studies have focused on serotonergic neurodegeneration in both disorders. We aimed to study degeneration of terminals with dopamine and serotonin transporter (DAT and SERT, respectively) in patients with early-stage PD and DLB relative to healthy controls, using 123I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropane (123I-FP-CIT) single photon emission computed tomography (SPECT). We conducted region of interest (ROI) and voxel-based analyses on 123I-FP-CIT SPECT scans. Using the cerebellum as a reference region, we determined binding ratios (BRs) for bilateral ROIs in the DAT-rich striatum (head of the caudate nucleus and posterior putamen) and SERT-rich extrastriatal brain regions (thalamus, hypothalamus and hippocampus). We compared BRs in PD and DLB patients with BRs in healthy controls (all groups: n = 16). Both PD and DLB patients had lower striatal 123I-FP-CIT BRs than healthy controls for the bilateral caudate head (PD-left: F(1,29) = 28.778, P < .001, ω2 = 0.35; right: F(1,29) = 35.338, P < .001, ω2 = 0.42; DLB-left: F(1,29) = 28.241, P < .001, ω2 = 0.31; right: F(1,29) = 18.811, P < .001, ω2 = 0.26) and bilateral posterior putamen (PD-left: F(1,29) = 107.531, P < .001, ω2 = 0.77; right: F(1,29) = 87.525, P < .001, ω2 = 0.72; DLB-left: F(1,29) = 39.910, P < .001, ω2 = 0.48; right: F(1,29) = 26.882, P < .001, ω2 = 0.38). DLB patients had lower hypothalamic 123I-FP-CIT BRs than healthy controls (F(1,29) = 6.059, P = .020, ω2 = 0.12). In the voxel-based analysis, PD and DLB patients had significantly lower striatal binding than healthy controls. Both PD patients in the early disease stages and DLB patients have reduced availability of striatal DAT, and DLB patients lower hypothalamic SERT compared with healthy controls. These observations add to the growing body of evidence that PD and DLB are not merely dopaminergic diseases, thereby providing additional clinicopathological insights.

Joling M ，Vriend C ，Raijmakers PGHM ，van der Zande JJ ，Lemstra AW ，Berendse HW ，Booij J ，van den Heuvel OA ... -  《NeuroImage-Clinical》

Extrastriatal (123)I-FP-CIT SPECT impairment in Parkinson's disease - the PPMI cohort.

Nicastro N ，Garibotto V ，Burkhard PR 《BMC Neurology》