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The purpose of this study was to assess the biological and clinical effects of n-acetyl-cysteine (NAC) in Parkinson's disease (PD). The overarching goal of this pilot study was to generate additional data about potentially protective properties of NAC in PD, using an in vitro and in vivo approach. In preparation for the clinical study we performed a cell tissue culture study with human embryonic stem cell (hESC)-derived midbrain dopamine (mDA) neurons that were treated with rotenone as a model for PD. The primary outcome in the cell tissue cultures was the number of cells that survived the insult with the neurotoxin rotenone. In the clinical study, patients continued their standard of care and were randomized to receive either daily NAC or were a waitlist control. Patients were evaluated before and after 3 months of receiving the NAC with DaTscan to measure dopamine transporter (DAT) binding and the Unified Parkinson's Disease Rating Scale (UPDRS) to measure clinical symptoms. The cell line study showed that NAC exposure resulted in significantly more mDA neurons surviving after exposure to rotenone compared to no NAC, consistent with the protective effects of NAC previously observed. The clinical study showed significantly increased DAT binding in the caudate and putamen (mean increase ranging from 4.4% to 7.8%; p<0.05 for all values) in the PD group treated with NAC, and no measurable changes in the control group. UPDRS scores were also significantly improved in the NAC group (mean improvement of 12.9%, p = 0.01). The results of this preliminary study demonstrate for the first time a potential direct effect of NAC on the dopamine system in PD patients, and this observation may be associated with positive clinical effects. A large-scale clinical trial to test the therapeutic efficacy of NAC in this population and to better elucidate the mechanism of action is warranted. ClinicalTrials.gov NCT02445651.

ObjectiveTo describe the incidence of, and clinical and neurobiological risk factors for, new-onset impulse control disorder (ICD) symptoms and related behaviours in early Parkinson disease (PD).MethodsThe Parkinson's Progression Markers Initiative is an international, multicenter, prospective study of de novo patients with PD untreated at baseline and assessed annually, including serial dopamine transporter imaging (DAT-SPECT) and ICD assessment (Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease short form, QUIP). Participants were included if they screened negative on the QUIP at baseline. Kaplan-Meier curves and generalised estimating equations examined frequency and predictors of incident ICD symptoms.ResultsParticipants were seen at baseline (n=320), year 1 (n=284), year 2 (n=217) and year 3 (n=96). Estimated cumulative incident rates of ICD symptoms and related behaviours were 8% (year 1), 18% (year 2) and 25% (year 3) and increased each year in those on dopamine replacement therapy (DRT) and decreased in those not on DRT. In participants on DRT, risk factors for incident ICD symptoms were younger age (OR=0.97, p=0.05), a greater decrease in right caudate (OR=4.03, p=0.01) and mean striatal (OR=6.90, p=0.04) DAT availability over the first year, and lower right putamen (OR=0.06, p=0.01) and mean total striatal (OR=0.25, p=0.04) DAT availability at any post-baseline visit.ConclusionsThe rate of incident ICD symptoms increases with time and initiation of DRT in early PD. In this preliminary study, a greater decrease or lower DAT binding over time increases risk of incident ICD symptoms, conferring additional risk to those taking DRT.Clinical trial registrationNCT01141023.

The dopamine transporter (DAT) mediates the reuptake of extracellular dopamine into presynaptic neurons. We investigated the effects of glucose loading on the striatal DAT in healthy young adults who underwent 18F‐FP‐CIT PET scans and completed a sweet taste questionnaire (STQ). Thirty‐five healthy participants were enrolled in this study. Each participant visited the institution three times for three brain PET scans (two 18F‐FP‐CIT PET scans after the infusion of glucose or placebo and one 18F‐Fluorodeoxyglucose PET scan). All participants underwent the 12‐item self‐reporting STQ to evaluate their reactions to eating sweet foods, cravings for sweet foods, and degree of control over eating sweet foods (STQ 1: sensitivity to the mood‐altering effect of sweet foods, and STQ 2: impaired control over eating sweet foods). In the caudate, glucose‐loaded DAT availability was significantly higher than placebo‐loaded DAT availability, and in the putamen, there was a trend toward higher DAT availability following glucose loading. The STQ was consistently positively related to glucose‐loaded DAT availability, not with placebo‐loaded DAT availability. In conclusion, changes in striatal DAT availability after glucose loading suggest an association with attitudes toward sweet foods in healthy young males. This may indicate that individuals with higher DAT availability after glucose loading experience rapid clearance of synaptic dopamine after consuming sweet foods, potentially leading to a desire for additional sweet foods. Changes in striatal DAT availability after glucose loading are associated with attitudes toward sweet foods. This may indicate that individuals with higher DAT availability after glucose loading experience rapid clearance of synaptic dopamine after consuming sweet foods, potentially leading to a desire for additional sweet foods.

The progression of neuroinflammation after anti-parkinsonian therapy on the Parkinson’s disease (PD) brain and in vivo evidence of the therapy purporting neuroprotection remain unclear. To elucidate this, we examined changes in microglial activation, nigrostriatal degeneration, and clinical symptoms longitudinally after dopamine replacement therapy in early, optimally-controlled PD patients with and without zonisamide treatment using positron emission tomography (PET). We enrolled sixteen PD patients (Hoehn and Yahr stage 1–2), and age-matched normal subjects. PD patients were randomly divided into two groups: one (zonisamide + ) that did and one (zonisamide − ) that did not undergo zonisamide therapy. Annual changes in neuroinflammation ([ 11 C]DPA713 PET), dopamine transporter availability ([ 11 C]CFT PET) and clinical severity were examined. Voxelwise differentiations in the binding of [ 11 C]DPA713 (BP ND ) and [ 11 C]CFT (SUVR) were compared with normal data and between the zonisamide + and zonisamide − PD groups. The cerebral [ 11 C]DPA713 BP ND increased with time predominantly over the parieto-occipital region in PD patients. Comparison of the zonisamide + group with the zonisamide − group showed lower levels in the cerebral [ 11 C]DPA713 BP ND in the zonisamide + group. While the striatal [ 11 C]CFT SUVR decreased longitudinally, the [ 11 C]CFT SUVR in the nucleus accumbens showed a higher binding in the zonisamide + group. A significant annual increase in attention score were found in the zonisamide + group. The current results indicate neuroinflammation proceeds to the whole brain even after anti-parkinsonian therapy, but zonisamide coadministration might have the potential to ameliorate proinflammatory responses, exerting a neuroprotective effect in more damaged nigrostriatal regions with enhanced attention in PD.

RationaleNicotine has been widely studied for its pro-dopaminergic effects. However, at the behavioural level, past investigations have yielded heterogeneous results concerning effects on cognitive, affective, and motor outcomes, possibly linked to individual differences at the level of genetics. A candidate polymorphism is the 40-base-pair variable number of tandem repeats polymorphism (rs28363170) in the SLC6A3 gene coding for the dopamine transporter (DAT). The polymorphism has been associated with striatal DAT availability (9R-carriers > 10R-homozygotes), and 9R-carriers have been shown to react more strongly to dopamine agonistic pharmacological challenges than 10R-homozygotes.ObjectivesIn this preregistered study, we hypothesized that 9R-carriers would be more responsive to nicotine due to genotype-related differences in DAT availability and resulting dopamine activity.MethodsN=194 non-smokers were grouped according to their genotype (9R-carriers, 10R-homozygotes) and received either 2-mg nicotine or placebo gum in a between-subject design. Spontaneous blink rate (SBR) was obtained as an indirect measure of striatal dopamine activity and smooth pursuit, stop signal, simple choice and affective processing tasks were carried out in randomized order.ResultsReaction times were decreased under nicotine compared to placebo in the simple choice and stop signal tasks, but nicotine and genotype had no effects on any of the other task outcomes. Conditional process analyses testing the mediating effect of SBR on performance and how this is affected by genotype yielded no significant results.ConclusionsOverall, we could not confirm our main hypothesis. Individual differences in nicotine response could not be explained by rs28363170 genotype.

Tourette syndrome (TS) is a neuropsychiatric disorder with childhood onset characterized by motor and phonic tics. Obsessive-compulsive disorder (OCD) is often concomitant with TS. Dysfunctional tonic and phasic dopamine (DA) and serotonin (5-HT) metabolism may play a role in the pathophysiology of TS. We simultaneously measured the density, affinity, and brain distribution of dopamine D 2 receptors (D 2 -R's), dopamine transporter binding potential (BP), and amphetamine-induced dopamine release (DA rel ) in 14 adults with TS and 10 normal adult controls. We also measured the brain distribution and BP of serotonin 5-HT 2A receptors (5-HT 2A R), and serotonin transporter (SERT) BP, in 11 subjects with TS and 10 normal control subjects. As compared with controls, DA rel was significantly increased in the ventral striatum among subjects with TS. Adults with TS+OCD exhibited a significant D 2 -R increase in left ventral striatum. SERT BP in midbrain and caudate/putamen was significantly increased in adults with TS (TS+OCD and TS-OCD). In three subjects with TS+OCD, in whom D 2 -R, 5-HT 2A R, and SERT were measured within a 12-month period, there was a weakly significant elevation of DA rel and 5-HT 2A BP, when compared with TS–OCD subjects and normal controls. The current study confirms, with a larger sample size and higher resolution PET scanning, our earlier report that elevated DA rel is a primary defect in TS. The finding of decreased SERT BP, and the possible elevation in 5-HT 2A R in individuals with TS who had increased DA rel , suggest a condition of increased phasic DA rel modulated by low 5-HT in concomitant OCD.

BACKGROUND. Recombinant human PDGF-BB (rhPDGF-BB) reduces Parkinsonian symptoms and increases dopamine transporter (DAT) binding in several animal models of Parkinson's disease (PD). Effects of rhPDGF-BB are the result of proliferation of ventricular wall progenitor cells and reversed by blocking mitosis. Based on these restorative effects, we assessed the safety and tolerability of intracerebroventricular (i.c.v.) rhPDGF-BB administration in individuals with PD. METHODS. We conducted a double-blind, randomized, placebo-controlled phase I/IIa study at two clinical centers in Sweden. Twelve patients with moderate PD received rhPDGF-BB via an implanted drug infusion pump and an investigational i.c.v. catheter. Patients were assigned to a dose cohort (0.2, 1.5, or 5 μg rhPDGF-BB per day) and then randomized to active treatment or placebo (3:1) for a 12-day treatment period. The primary objective was to assess safety and tolerability of i.c.v.-delivered rhPDGF-BB. Secondary outcome assessments included several clinical rating scales and changes in DAT binding. The follow-up period was 85 days. RESULTS. All patients completed the study. There were no unresolved adverse events. Serious adverse events occurred in three patients; however, these were unrelated to rhPDGF-BB administration. Secondary outcome parameters did not show dose-dependent changes in clinical rating scales, but there was a positive effect on DAT binding in the right putamen. CONCLUSION. At all doses tested, i.c.v. administration of rhPDGF-BB was well tolerated. Results support further clinical development of rhPDGF-BB for patients with PD. TRIAL REGISTRATION. Clinical Trials.gov NCT00866502. FUNDING. Newron Sweden AB (former NeuroNova AB) and Swedish Governmental Agency for Innovation Systems (VINNOVA).

Dopamine function and reward processing are highly interrelated and involve common brain regions afferent to the nucleus accumbens, within the mesolimbic pathway. Although dopamine function and reward system neural activity are impaired in most psychiatric disorders, it is unknown whether alterations in the dopamine system underlie variations in reward processing across a continuum encompassing health and these disorders. We explored the relationship between dopamine function and neural activity during reward anticipation in 27 participants including healthy volunteers and psychiatric patients with schizophrenia, depression, or cocaine addiction, using functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) multimodal imaging with a voxel-based statistical approach. Dopamine transporter (DAT) availability was assessed with PET and [11 C]PE2I as a marker of presynaptic dopamine function, and reward-related neural response was assessed using fMRI with a modified Monetary Incentive Delay task. Across all the participants, DAT availability in the midbrain correlated positively with the neural response to anticipation of reward in the nucleus accumbens. Moreover, this relationship was conserved in each clinical subgroup, despite the heterogeneity of mental illnesses examined. For the first time, a direct link between DAT availability and reward anticipation was detected within the mesolimbic pathway in healthy and psychiatric participants, and suggests that dopaminergic dysfunction is a common mechanism underlying the alterations of reward processing observed in patients across diagnostic categories. The findings support the use of a dimensional approach in psychiatry, as promoted by the Research Domain Criteria project to identify neurobiological signatures of core dysfunctions underling mental illnesses.

Intellectual drug doping in athletics by using stimulants that affect central nervous system functions has been diversified. Stimulants are regulated by the World Anti-Doping Agency according to their levels of urinary concentration. Positron emission tomography could evaluate how stimulants affect central nervous system functions. We aimed to evaluate the effect of stimulants on brain function by examining the difference in brain dopamine transporter occupancy by PET after administration of dl -methylephedrine or pseudoephedrine at the clinical maximum daily dose. Four PET scans without and with drug administration (placebo, dl -methylephedrine 150 mg and pseudoephedrine 240 mg) were performed. The concentrations of dl -methylephedrine and pseudoephedrine in plasma and urine were measured. DAT occupancies in the striatum with placebo, dl -methylephedrine and pseudoephedrine were calculated by PET images. The urinary concentration of dl -methylephedrine (12.7 µg/mL) exceeded the prohibited concentration (10 µg/mL), but the DAT occupancy with dl -methylephedrine (6.1%) did not differ (p = 0.92) from that with placebo (6.2%). By contrast, although the urinary concentration of pseudoephedrine (144.8 µg/mL) was below the prohibited concentration (150 μg/mL), DAT occupancy with pseudoephedrine was 18.4%, which was higher than that with placebo (p = 0.009). At the maximum clinical dose, dl -methylephedrine was shown to have weaker effects on brain function than pseudoephedrine.

Dementia with Lewy bodies (DLB) is underrecognised in clinical settings. To investigate whether performing a (123)I-ioflupane injection ((123)I-FP-CIT also called DaTSCAN™) single photon emission computed tomography (SPECT) scan in patients with possible DLB would lead to a more certain diagnosis (probable DLB or non-DLB dementia). We randomised 187 patients with possible DLB 2:1 to have a scan or not (control group). The outcome measure was a change in diagnosis to probable DLB or non-DLB. There were 56 controls and 114 scanned patients, of whom 43% had an abnormal scan. More patients in the imaging group had a change in diagnosis compared with controls at 8 and 24 weeks (61% (n = 70) v. 4% (n = 2) and 71% (n = 77) v. 16% (n = 9); both P<0.0001). Clinicians were more likely to change the diagnosis if the scan was abnormal (82%) than if it was normal (46%). Imaging significantly contributed to a more certain diagnosis, proving to be a useful adjunct in the work-up of patients with possible DLB.