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Dean F Wong

Publications and source records attributed to Dean F Wong.

At least 19 recordsLinked to original sources
PubMed2006

Increased occupancy of dopamine receptors in human striatum during cue-elicited cocaine craving.

In all, 19 research subjects, with current histories of frequent cocaine use, were exposed to cocaine-related cues to elicit drug craving. We measured the change of occupancy of dopamine at D2-like receptors with positron emission tomography (PET) and inferred a change of intrasynaptic dopamine (endogenous dopamine release), based on the displacement of radiotracer [(11)C]raclopride. Receptor occupancy by dopamine increased significantly in putamen of participants who reported cue-elicited craving compared to those who did not. Further, the intensity of craving was positively correlated with the increase in dopamine receptor occupancy in the putamen. These results provide direct evidence that occupancy of dopamine receptors in human dorsal striatum increased in proportion to subjective craving, presumably because of increased release of intrasynaptic dopamine.

Adult↗
PubMed2006

Nigrostriatal dopamine system dysfunction and subtle motor deficits in manganese-exposed non-human primates.

We tested the hypothesis that movement abnormalities induced by chronic manganese (Mn) exposure are mediated by dysfunction of the nigrostriatal dopamine system in the non-human primate striatum. Motor function and general activity of animals was monitored in parallel with chronic exposure to Mn and Positron Emission Tomography (PET) studies of in vivo dopamine release, dopamine transporters and dopamine receptors in the striatum. Analysis of metal concentrations in whole blood and brain was obtained and post-mortem analysis of brain tissue was used to confirm the in vivo PET findings. Chronic Mn exposure resulted in subtle motor function deficits that were associated with a marked decrease of in vivo dopamine release in the absence of a change in markers of dopamine (DA) terminal integrity or dopamine receptors in the striatum. These alterations in nigrostriatal DA system function were observed at blood Mn concentrations within the upper range of environmental, medical and occupational exposures in humans. These findings show that Mn-exposed non-human primates that exhibit subtle motor function deficits have an apparently intact but dysfunctional nigrostriatal DA system and provide a novel mechanism of Mn effects on the dopaminergic system.

Amphetamine↗
PubMed2006

An extended simplified reference tissue model for the quantification of dynamic PET with amphetamine challenge.

BACKGROUND: Equilibrium analysis to quantify dynamic positron emission tomography (PET) with bolus followed by continuous tracer infusion and acute amphetamine challenge assumes that all tissue kinetics attain steady states during pre- and post-challenge phases. Violations of this assumption may result in unreliable estimation of the amphetamine-induced percent change in the binding potential (DeltaBP%). METHOD: We derived an extended simplified reference tissue model (ESRTM) for modeling tracer kinetics in the pre- and post-challenge phases. Ninety-minute [11C]raclopride PET studies with bolus injection followed by continuous tracer infusion were performed on 18 monkeys and 2 baboons. Forty minutes after the bolus injection, a single acute intravenous amphetamine administration was given of 2.0 mg/kg to monkeys and of 0.05, 0.1, 0.5, and 1.5 mg/kg to baboons. Computer simulations further evaluated and characterized the ESRTM. RESULTS: In monkey studies, the DeltaBP% estimated by the ESRTM was 32+/-11, whereas, the DeltaBP% obtained using the equilibrium methods was 32% to 81% lower. In baboon studies, the DeltaBP% values estimated with the ESRTM showed a linear relationship between the DeltaBP% and the natural logarithm of amphetamine dose (R2=0.96), where the DeltaBP%=10.67Ln(dose)+33.79 (0.05<or=dose in mg/kg<or=1.5). At 1.5 mg/kg amphetamine, the DeltaBP% estimates from equilibrium methods were 18% to 40% lower than those estimated by the ESRTM. Results showed that the nonsteady state of tracer kinetics produced an underestimation of the DeltaBP% from the equilibrium analysis. The accuracy of the DeltaBP% estimates from the equilibrium analysis was significantly improved by the ESRTM. The DeltaBP% estimated by the ESRTM in the study was consistent with that from previous [11C] raclopride PET with amphetamine challenge. CONCLUSION: In conclusion, the ESRTM is a robust kinetic modeling approach and is proposed for the quantification of dynamic PET with acute amphetamine stimulation.

Amphetamine↗
PubMed2006

Dose effects of triazolam on brain activity during episodic memory encoding: a PET study.

RATIONALE: Although it is well established that acute benzodiazepine administration impairs episodic memory encoding, little is known about the neuroanatomical substrates of this effect. OBJECTIVE: The objective was to examine the acute dose effects of the benzodiazepine hypnotic triazolam on brain activity during episodic memory encoding. METHODS: After oral capsule administration (placebo, 0.1, 0.2, and 0.4 mg/70 kg triazolam), regional cerebral blood flow (rCBF) was measured using positron emission tomography (PET) with 15O-H2O during performance of semantic categorization and orthographic categorization tasks in a double-blind, within-subject design in 12 healthy volunteers. The rCBF associated with episodic memory encoding was measured by subtracting the rCBF during orthographic categorization from that during semantic categorization and by examining correlations between brain activity during encoding and subsequent recognition memory performance. RESULTS: Results in the placebo condition replicated those of nonpharmacological encoding studies, including activation in left ventrolateral prefrontal cortex. Correlations between brain activity and subsequent memory performance additionally showed medial temporal activation. Triazolam produced dose-related impairment in memory performance and dose-related deactivation in encoding-associated areas including right prefrontal cortex, left parahippocampal gyrus, and left anterior cingulate cortex. CONCLUSIONS: Results are consistent with behavioral evidence that benzodiazepines impair prefrontal control processes as well as contextual memory and episodic binding processes thought to be controlled by the medial temporal lobe. In addition to elucidating the brain mechanisms underlying these benzodiazepine-induced behavioral deficits, results of this study also help validate hypotheses generated in nonpharmacological neuroimaging studies regarding the processes controlled by these brain regions.

Adult↗
PubMed2006

Sex differences in striatal dopamine release in healthy adults.

BACKGROUND: Sex differences in addictive disorders have been described. Preclinical studies have implicated the striatal dopamine system in these differences, but human studies have yet to substantiate these findings. METHODS: Using positron emission tomography (PET) scans with high-specific-activity [11C] raclopride and a reference tissue approach, we compared baseline striatal dopamine binding potential (BP) and dopamine release in men and women following amphetamine and placebo challenges. Subjective drug effects and plasma cortisol and growth hormone responses were also examined. RESULTS: Although there was no sex difference in baseline BP, men had markedly greater dopamine release than women in the ventral striatum. Secondary analyses indicated that men also had greater dopamine release in three of four additional striatal regions. Paralleling the PET findings, men's ratings of the positive effects of amphetamine were greater than women's. We found no sex difference in neuroendocrine hormone responses. CONCLUSIONS: We report for the first time a sex difference in dopamine release in humans. The robust dopamine release in men could account for increased vulnerability to stimulant use disorders and methamphetamine toxicity. Our findings indicate that future studies should control for sex and may have implications for the interpretation of sex differences in other illnesses involving the striatum.

Adult↗
PubMed2006

The striatal and extrastriatal D2/D3 receptor-binding profile of clozapine in patients with schizophrenia.

Positron emission tomography (PET) studies reveal that clozapine at clinically used doses occupies less than 60% of D2/D3 dopamine receptors in human striatum. Here, the occupancy of D2/D3 dopamine receptors by clozapine in patients with schizophrenia was determined to test the hypothesis that clozapine binds preferentially to extrastriatal dopamine receptors. A total of 15 clozapine-treated inpatients with schizophrenia underwent a [18F]fallypride PET scan. Receptor occupancy was calculated as percent reduction in binding potential relative to unblocked values measured in seven normal volunteers. Mean D2/D3 receptor occupancy was statistically significantly higher in cortical (inferior temporal cortex 55%) than in striatal regions (putamen 36%, caudate 43%, p<0.005). While the maximum attainable receptor occupancy Emax approached 100% both in the striatum and cortex, the plasma concentration at 50% of Emax (ED50) was much higher in the putamen (950 ng/ml) than in the inferior temporal cortex (333 ng/ml). Clozapine binds preferentially to cortical D2/D3 receptors over a wide range of plasma concentrations. This selectivity is lost at extremely high plasma levels. Occupancy of cortical receptors approaches 60% with plasma clozapine in the range 350-400 ng/ml, which corresponds to the threshold for antipsychotic efficacy of clozapine. Extrastriatal binding of clozapine may be more relevant to its antipsychotic actions than striatal. However, further studies with an intraindividual comparison of untreated vs treated state are desirable to confirm this finding.

Adult↗
PubMed2006

Striatal dopamine release and family history of alcoholism.

BACKGROUND: The offspring of alcohol-dependent individuals are at increased risk for alcoholism. The present study was designed to determine whether mesolimbic dopamine binding potential (BP), dopamine release, stress hormones, and subjective responses to intravenous amphetamine are different in nonalcoholic offspring from families with a history of alcohol dependence [family history positive (FHP)] than in nonalcoholic offspring without a family history of alcohol dependence [family history negative (FHN)]. METHODS: Participants were 41 healthy men and women (11 FHP, 30 FHN; age range 18-29). After completing baseline psychiatric symptom and personality measures, striatal D2/D3 dopamine BP and dopamine release in response to an amphetamine challenge were measured with positron emission tomography (PET) using the D2/D3 dopamine (DA) receptor radioligand [11C]raclopride. Binding potential was defined as Bmax/KD, percent change in BP from baseline defined dopamine release. During the scans, subjects rated the degree to which they were experiencing each of 10 possible drug effects. Plasma cortisol and growth hormone (GH) were also measured at scheduled intervals during the scans. RESULTS: Neither baseline BP nor dopamine release differed by family history. Similarly, subjective responses to amphetamine did not differ by a family history of alcoholism. Although both cortisol and GH increased following administration of amphetamine, these increases did not differ between family history groups. CONCLUSIONS: Using amphetamine to provoke mesolimbic dopamine, we did not show significant differences in dopamine release, subjective responses, or stress hormone measures as a function of family history of alcoholism.

Adolescent↗
PubMed2006

11C-JHU75528: a radiotracer for PET imaging of CB1 cannabinoid receptors.

UNLABELLED: The development of the radioligands for PET imaging of the cerebral cannabinoid receptor (CB1) is of great importance for studying its role in neuropsychiatric disorders, obesity, and drug dependence. None of the currently available radioligands for CB1 are suitable for quantitative PET, primarily because of their insufficient binding potential (BP) in brain or low penetration through the blood-brain barrier (BBB). The goal of this study was to evaluate 11C-JHU75528, an analog of the selective CB1 antagonist rimonabant, in vivo as a potential CB1 radioligand for PET. METHODS: The brain regional distribution and pharmacology of 11C-JHU75528 have been evaluated in vivo in mice (dissection) and baboons (PET). RESULTS: 11C-JHU75528 readily entered the mouse and baboon brain and specifically and selectively labeled cerebral CB1 receptors. The ratio of striatum to brain stem in mice and the binding potential (BP) in the baboon putamen were 3.4 and 1.3-1.5, respectively. The specific binding of 11C-JHU75528 in vivo was blocked by preinjection of nonlabeled JHU75528. Administration of rimonabant (1 mg/kg, intravenously) also blocked the specific binding of 11C-JHU75528 in the mouse and baboon brain, whereas various central noncannabinoid drugs did not significantly reduce the 11C-JHU75528 binding in the mouse brain. 11C-JHU75528 formed several hydrophilic metabolites, but only a minute fraction of metabolic radioactivity penetrated the BBB. CONCLUSION: 11C-JHU75528 holds promise as a radiotracer with suitable imaging properties for quantification of CB1 receptors in the human brain.

Animals↗
PubMed2005

Acute manganese administration alters dopamine transporter levels in the non-human primate striatum.

We used positron emission tomography (PET) to measure non-invasively the effect of acute systemic administration to manganese sulfate (MnSO4) on dopamine transporter (DAT) levels in the living non-human primate brain. Baboons received [11C]-WIN 35,428 PET scans to measure DAT levels before and after acute MnSO4 administration. In one animal, we observed a 46% increase in DAT binding potential (BP), a measure of DAT binding site availability, 1 week after Mn administration. DAT levels returned to baseline values at 4 months and remained constant at 10 months after treatment. A subsequent single MnSO4 injection to the same animal also resulted in a 57% increase in DAT-BP, 2 days after administration. In a second animal, a 76% increase in DAT-BP relative to baseline was observed at 3 days after Mn injection. In this animal, the DAT-BP returned to baseline levels after 1 month. Using in vitro receptor binding assays, we found that Mn inhibits [3H]-WIN 35,428 binding to rat striatal DAT with an inhibitory constant (Ki) of 2.0+/-0.3mM (n=4). Saturation isotherms and Scatchard analysis of [3H]-WIN 35,428 binding to rat striatal DAT showed a significant decrease (30%, p<0.001) in the maximal number of binding sites (Bmax) in the presence of 2mM MnSO4. No significant effect of Mn was found on binding affinity (Kd). We also found that Mn inhibits [3H]-dopamine uptake with an IC50 of 11.4+/-1.5mM (n=4). Kinetic studies and Lineweaver-Burk analysis showed a significant decrease (40%, p<0.001) in the maximal velocity of uptake (Vmax) with 5mM MnSO4. No significant effect of Mn was found on Michaelis-Menten constant (Km). These in vitro findings suggest that the increase in DAT levels in vivo following acute Mn administration may be a compensatory response to its inhibitory action on DAT. These findings provide helpful insights on potential mechanisms of Mn-induced neurotoxicity and indicate that the DAT in the striatum is a target for Mn in the brain.

Animals↗
PubMed2005

Effect of worry on regional cerebral blood flow in nonanxious subjects.

Several studies suggest that cognitive tasks attenuate activation of the limbic system by emotional stimuli. We investigated the possibility that worry would similarly inhibit the limbic system by examining its effects on regional cerebral blood flow (rCBF). Ten nonanxious volunteers underwent four scans within one session, using positron emission tomography (PET) with H(2)(15)O as tracer. The first two scans recorded emotionally neutral thinking induced after listening to tapes describing neutral statements. Preceding the third and fourth scans, subjects listened to the self-recorded tape describing their individual worries, were instructed to continue to worry, and were scanned 5 min later. Subjects rated themselves as more anxious during the worry scans but showed no significant heart interbeat or skin conductance changes. During worry, rCBF increases were found bilaterally in the medial fronto-orbital gyri and the right thalamus; rCBF decreases were found bilaterally in the hippocampi and amygdalae, in the right insula, the left and right inferior, middle and superior temporal gyri and the occipito-temporal gyri, the right inferior occipital gyrus and the left supramarginal gyrus. Activity of the left orbito-frontal gyrus was negatively correlated with activity of the amygdalae. The results support the hypothesis that worry-induced prefrontal activity suppresses affect-related subcortical regions.

Adult↗
PubMed2005

Synthesis and in vivo evaluation of a new PET radioligand for studying sigma-2 receptors.

The cyclohexyl piperazine 1 (1-cyclohexyl-4-[3-(5-methoxy-1,2,3,4-tetrahydro-naphthalen-1-yl)-propyl]-piperazine) has been shown to be a potent and selective sigma-2 receptor ligand. In the present study, we prepared [(11)C]1 by O-alkylation of the phenolic precursor 2 with [(11)C]CH(3)I. [(11)C]1 was obtained in a 29% non-decay corrected yield and specific activity of 9299 mCi/micromol calculated at end-of-synthesis. The biodistribution of [(11)C]1 in mouse brain demonstrated rapid and homogenous concentration in all brain structures, which included the cortex, thalamus, cerebellum and striatum. Co-administration of unlabelled 1 (1 mg/kg) or the sigma-2 selective ligand SM-21 (1 mg/kg) failed to show any significant inhibition of [(11)C]1 uptake in the mouse brain. The evaluation of this radioligand in vivo in the mouse clearly indicates that it does not possess the required properties for studying sigma-2 receptors in the brain using PET.

Animals↗
PubMed2005

Noradrenergic and dopaminergic effects of (+)-amphetamine-like stimulants in the baboon Papio anubis.

(+)-Amphetamine, (+/-)-ephedrine, and phentermine are commonly used appetite suppressants that release monoamines from nerve cells by acting as substrates for biogenic amine transporters. One key difference among the three drugs is their selectivity for norepinephrine (NE) release vs. dopamine (DA) release. The NE/DA selectivity ratios for these drugs as determined in vitro [(EC50 NE(-1))/(EC50 DA(-1))] are (+/-)-ephedrine (18.6) > phentermine (6.7) > (+)-amphetamine (3.5). The in vitro data suggest that when administered in vivo, these stimulants might differ in their ability to release DA from nerve terminals in the brain. To test this hypothesis, noradrenergic effects (i.e., plasma NE) and dopaminergic effects (i.e., central DA release) were assessed when each drug was administered intravenously (1.5 mg/kg) to anesthetized baboons. Central DA release was determined via positron emission tomography using the method of [11C]raclopride displacement. In the present investigation, high doses of these stimulants increased plasma NE and DA in parallel, but only (+)-amphetamine released central DA from neurons and decreased plasma prolactin. None of the drugs altered plasma amine metabolite levels, indicating no inhibition of monoamine oxidase activity at the administered doses. Plasma drug levels measured in baboons were higher than those measured in human patients taking prescribed doses of the drugs. Viewed collectively, the present data indicate that typical clinical doses of phentermine and (+/-)-ephedrine may not release central DA in humans, a hypothesis that should ultimately be tested in controlled clinical studies.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2005

Relationships among ventral striatal dopamine release, cortisol secretion, and subjective responses to amphetamine.

There is evidence that stress and glucocorticoids alter drug self-administration and mesolimbic dopamine (DA) activity in preclinical models. The primary purpose of this study was to test the hypothesis that glucocorticoids are associated with psychostimulant reinforcement and DA release in humans. In total, 16 healthy adults, ages 18-27 years, underwent two consecutive 90-min PET studies with high specific activity [11C]raclopride. The first scan was preceded by intravenous saline, and the second by intravenous amphetamine (AMPH 0.3 mg/kg). DA release was defined as the percent change in raclopride binding between the placebo and AMPH scans. Measures of subjective drug effects, plasma cortisol, and growth hormone (GH) were obtained. Findings showed that cortisol levels were positively associated with AMPH-induced DA release in the left ventral striatum (LVS) and the dorsal putamen. Subjects with higher cortisol responses to AMPH also reported more positive subjective drug effects than subjects with lower cortisol responses; no association was observed between cortisol levels and negative drug effects. Higher ratings of positive drug effects were also associated with greater DA release in the LVS, dorsal putamen, and dorsal caudate. A general lack of relationship was observed between GH responses to AMPH and DA release or subjective drug responses. Our findings provide evidence of interrelationships between glucocorticoid levels, subjective responses to IV AMPH, and brain DA release in humans. The results are consistent with those of preclinical studies, suggesting that individual differences in HPA axis function may influence vulnerability to alcohol and drug dependence in humans.

Adolescent↗
PubMed2005

Imaging glial cell activation with [11C]-R-PK11195 in patients with AIDS.

Glial cell activation occurs in response to brain injury and is present in a wide variety of inflammatory processes including dementia associated with human immunodeficiency virus (HIV). HIV-infected glial cells release cytokines and chemokines that, along with viral neurotoxins, contribute to neuronal damage and apoptosis. The purpose of this study was to determine if glial cell activation in HIV-positive (HIV+) patients could be detected noninvasively, in vivo, using [11C]-R-PK11195 with positron emission tomography (PET). [11C]-R-PK11195 is a selective radioligand for the peripheral benzodiazepine receptor (PBR), and is known to reflect the extent of glial cell activation. A subaim was to determine if nondemented HIV+ patients could be distinguished from those with HIV-associated dementia (HAD) on the basis of [11C]-R-PK11195 binding. Five healthy volunteers and 10 HIV+ patients underwent PET with [11C]-R-PK11195. Time-radioactivity curves (TACs) were generated from dynamic PET images in nine regions of interest (ROIs) drawn on coregistered magnetic resonance imaging (MRI) scans. The average radioactivity was calculated in each ROI and was normalized to the average radioactivity in white matter. Patients with HAD showed significantly higher [11C]-R-PK11195 binding than controls in five out of eight brain regions (P < .05, Mann-Whitney U test). Nondemented HIV+ patients did not show significantly increased binding compared to controls. HIV+ patients overall (demented and nondemented) showed significantly higher radioligand binding than controls in five brain regions (P < 0.05). Patients with HAD did not show significant differences in binding when compared to HIV+ nondemented patients. The findings of this pilot study support a role for glial cell activation in HAD, and that PET with [11C]-R-PK11195 can detect the concomitants of neuronal damage in individuals infected with HIV.

AIDS Dementia Complex↗
PubMed2005

Parametric mapping of binding in human brain of D2 receptor ligands of different affinities.

UNLABELLED: (11)C-Raclopride has been widely used for PET studies of dopamine D(2/3) receptors in human brain. The long half-life of (18)F may impart advantages to the novel moderate-affinity benzamide (18)F-desmethoxyfallypride and its high-affinity congener (18)F-fallypride for competition studies and for detection of extrastriatal binding. However, the in vivo kinetics of these compounds and the quantification approaches for parametric mapping of their specific bindings have not been systematically compared. METHODS: Dynamic emission recordings of the 3 tracers were obtained in groups of healthy subjects. A conventional model, graphical analysis using metabolite-corrected arterial inputs, and models with reference tissue inputs were used to calculate voxelwise parametric maps of the equilibrium distribution volume (V(d)) and the binding potential (BP) of the 3 radioligands in brain. To test for bias, voxelwise kinetic results were compared with those obtained by volume-of-interest (VOI) analysis. RESULTS: The V(d) and BP estimates obtained by VOI analysis did not differ from the mean of voxelwise estimates in the same striatal volumes. In striatum, the mean (18)F-desmethoxyfallypride BP ranged from 1.9 to 2.5, whereas the mean (11)C-raclopride BP ranged from 3 to 4, depending on the method used for calculation. In contrast, the mean BP of (18)F-fallypride ranged from 16 to 27 in striatum and could also be readily quantified in the thalamus. CONCLUSION: Reference tissue methods for the voxelwise calculation of binding parameters are suitable for parametric mapping of the 3 dopamine D(2/3) receptor ligands.

Adult↗
PubMed2004

Central effects of fexofenadine and cetirizine: measurement of psychomotor performance, subjective sleepiness, and brain histamine H1-receptor occupancy using 11C-doxepin positron emission tomography.

Histamine H1-receptor (H1R) antagonists, or antihistamines, often induce sedative side effects when used for the treatment of allergic disorders. This study compared the sedative profiles of the second-generation antihistamines, fexofenadine and cetirizine, using 3 different criteria: subjective sleepiness evaluated by the Stanford Sleepiness Scale, objective psychomotor tests (simple and choice reaction time tests and visual discrimination tests at 4 different exposure durations), and measurement of histamine H1-receptor occupancy (H1RO) in the brain. Subjective sleepiness and psychomotor performance were measured in 20 healthy Japanese volunteers at baseline and 90 min after administration of fexofenadine 120 mg or cetirizine 20 mg in a double-blind, placebo-controlled crossover study. Hydroxyzine 30 mg was included as a positive control. H1RO was measured using positron emission tomography (PET) with (11)C-doxepin in 12 of the 20 subjects, and a further 11 volunteers were recruited to act as controls. In psychomotor tests, fexofenadine was not significantly different from placebo and significantly less impairing than cetirizine on some tasks, as well as significantly less impairing than hydroxyzine on all tasks. For subjective sleepiness, fexofenadine was not significantly different from placebo, whereas cetirizine showed a trend toward increased sleepiness compared with fexofenadine and placebo. H1RO was negligible with fexofenadine (-0.1%) but moderately high with cetirizine (26.0%). In conclusion, fexofenadine 120 mg is distinguishable from cetirizine 20 mg, as assessed by H1RO and psychomotor testing.

Adult↗
PubMed2003

Positron emission tomography of striatal serotonin transporters in Parkinson disease.

BACKGROUND: Little is known about serotonin neurons in Parkinson disease (PD). OBJECTIVE: To study the serotonin system in PD with positron emission tomography, using the serotonin transporter radioligand [11C](+)McN5652. DESIGN AND PATIENTS: We measured the density of the serotonin transporter and the density of [11C]WIN35,428-labeled dopamine transporters in the striatum of 13 adults with PD and 13 age- and sex-matched controls. To assess the effects of possible differences in blood flow or brain atrophy, we also measured regional cerebral blood flow and the size of the regions of interest for the caudate nucleus and putamen. RESULTS: Patients with PD showed reductions in the specific distribution volumes of [11C](+)McN5652 in the caudate (P<.01) and putamen (P<.01), along with the expected reductions in striatal [11C]WIN35,428 binding (P<.01). There were no reductions in regional cerebral blood flow or the sizes of the regions of interest, mitigating against potential confounding effects of blood flow, brain atrophy, or partial volume effects. Reductions in serotonin transporter binding correlated with ratings of disease staging. CONCLUSIONS: These results suggest that the density of serotonin transporters, like that of dopamine transporters, is reduced in the striatum of patients with PD and that these changes are related to disease stage.

Adult↗