| 1. |
- Appel, Lieuwe, et al.
(författare)
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Altered NK1-receptor availability in patients with post traumatic stress disorder
- 2009
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Ingår i: [Biological Psychiatry 2009, 65(8), Suppl. 1, 118S, no. 394]. - : Elsevier BV. ; , s. 118S-
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Konferensbidrag (refereegranskat)abstract
- Background: Posttraumatic stress disorder (PTSD) is an anxiety disorder that can develop after one or more traumatic events causing extreme stress or grave physical harm. The neurokinin-1 (NK1) receptor is the primary receptor for substance P (SP); a neuropeptide suggested being involved in anxiety and depression. The present study investigated differences in NK1-receptor availability between PTSD patients and healthy controls, using positron emission tomography (PET). Methods: Eleven male refugee patients (age: 41±10) with DSM-IV defined PTSD and nine healthy male control subjects (age: 33±10) were investigated using the PET-tracer [11C]GR205171, supplied by Uppsala Imanet. GR205171 is a highly selective NK1-receptor antagonist. Scans were performed during 60 minutes in the resting state. Parametric images were generated using the graphical reference Patlak method assuming irreversible binding of [11C]GR205171 from 20-60 minutes and having cerebellum as reference region. Exploratory whole brain analyses were performed using the statistical parametric mapping (SPM2) software. Results: PTSD patients had lower [11C]GR205171 binding compared to controls, in frontal cortical clusters encompassing bilaterally insula and left Brodmann area 11, reflecting lower NK1-receptor availability. No areas were found in which PTSD patients had higher [11C]GR205171 binding. Conclusions: This is the first study reporting differences in NK1-receptor availability in PTSD patients relative to controls. A tentative conclusion is that PTSD patients have a down regulation of the NK1-receptor system, which could be either a risk factor or due to emotional trauma processing.
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| 2. |
- Appel, Lieuwe, et al.
(författare)
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BL-1020, a novel antipsychotic candidate with GABA-enhancing effects : D2 receptor occupancy study in humans
- 2009
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Ingår i: European Neuropsychopharmacology. - : Elsevier BV. - 0924-977X .- 1873-7862. ; 19:12, s. 841-850
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Tidskriftsartikel (refereegranskat)abstract
- BL-1020 is a potentially novel antipsychotic, which comprises the typical antipsychotic perphenazine linked by an ester bound to gamma-aminobutyric acid (GABA), intending a simultaneous dopamine-2 (D(2)) receptor blockade and GABA facilitation in the brain. This positron emission tomography (PET) study, using [(11)C]raclopride, assessed the extent and duration of D(2) receptor occupancy (D(2) RO) and safety for single doses of BL-1020 in healthy male subjects. Overall, this study did not raise any safety concern. Single doses of 16-32 mg BL-1020 caused a dose dependent striatal D(2) RO. The 32 mg dose of BL-1020 resulted in an average D(2) RO of 44% at 4-6 h post dosing (pd), which declined to 33% at 24 h pd. Equimolar doses of BL-1020 and perphenazine resulted in similar D(2) RO at 24 h pd. Pharmacokinetic-pharmacodynamic analysis predicted that oral once daily administration of 32 mg BL-1020 would result in D(2) ROs ranging from 52 to 66% at a steady state.
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| 3. |
- Furmark, Tomas, et al.
(författare)
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A link between serotonin-related gene polymorphisms, amygdala activity, and placebo-induced relief from social anxiety
- 2008
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 28:49, s. 13066-74
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Tidskriftsartikel (refereegranskat)abstract
- Placebo may yield beneficial effects that are indistinguishable from those of active medication, but the factors underlying proneness to respond to placebo are widely unknown. Here, we used functional neuroimaging to examine neural correlates of anxiety reduction resulting from sustained placebo treatment under randomized double-blind conditions, in patients with social anxiety disorder. Brain activity was assessed during a stressful public speaking task by means of positron emission tomography before and after an 8 week treatment period. Patients were genotyped with respect to the serotonin transporter-linked polymorphic region (5-HTTLPR) and the G-703T polymorphism in the tryptophan hydroxylase-2 (TPH2) gene promoter. Results showed that placebo response was accompanied by reduced stress-related activity in the amygdala, a brain region crucial for emotional processing. However, attenuated amygdala activity was demonstrable only in subjects who were homozygous for the long allele of the 5-HTTLPR or the G variant of the TPH2 G-703T polymorphism, and not in carriers of short or T alleles. Moreover, the TPH2 polymorphism was a significant predictor of clinical placebo response, homozygosity for the G allele being associated with greater improvement in anxiety symptoms. Path analysis supported that the genetic effect on symptomatic improvement with placebo is mediated by its effect on amygdala activity. Hence, our study shows, for the first time, evidence of a link between genetically controlled serotonergic modulation of amygdala activity and placebo-induced anxiety relief.
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| 4. |
- Furmark, Tomas, et al.
(författare)
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Cerebral blood flow changes after treatment of social phobia with the neurokinin-1 antagonist GR205171, citalopram, or placebo.
- 2005
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Ingår i: Biol Psychiatry. - : Elsevier. - 0006-3223 .- 1873-2402. ; 58:2, s. 132-42
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: Evidence is accumulating that pharmacological blockade of the substance P preferring neurokinin-1 (NK1) receptor reduces anxiety. This study compared the effects of an NK1 receptor antagonist, citalopram, and placebo on brain activity and anxiety symptoms in social phobia. METHODS: Thirty-six patients diagnosed with social phobia were treated for 6 weeks with the NK1 antagonist GR205171 (5 mg), citalopram (40 mg), or matching placebo under randomized double-blind conditions. GR205171 was administered for 4 weeks preceded by 2 weeks of placebo. Before and after treatment, regional cerebral blood flow (rCBF) during a stressful public speaking task was assessed using oxygen-15 positron emission tomography. Response rate was determined by the Clinical Global Impression Improvement Scale. RESULTS: Patients improved to a larger extent with the NK1 antagonist (41.7% responders) and citalopram (50% responders), compared with placebo (8.3% responders). Within- and between-group comparisons showed that symptom improvement was paralleled by a significantly reduced rCBF response to public speaking in the rhinal cortex, amygdala, and parahippocampal-hippocampal regions. The rCBF pattern was corroborated in follow-up analyses of responders and subjects showing large state anxiety reduction. CONCLUSIONS: Short-term administration of GR205171 and citalopram alleviated social anxiety. Neurokinin-1 antagonists may act like serotonin reuptake inhibitors by attenuating neural activity in a medial temporal lobe network.
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| 5. |
- Furmark, Tomas, et al.
(författare)
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Genotype over-diagnosis in amygdala responsiveness: affective processing in social anxiety disorder.
- 2009
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Ingår i: Journal of psychiatry & neuroscience : JPN. - : Canadian Medical Association. - 1488-2434 .- 1180-4882. ; 34:1, s. 30-40
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although the amygdala is thought to be a crucial brain region for negative affect, neuroimaging studies do not always show enhanced amygdala response to aversive stimuli in patients with anxiety disorders. Serotonin (5-HT)-related genotypes may contribute to interindividual variability in amygdala responsiveness. The short (s) allele of the 5-HT transporter linked polymorphic region (5-HTTLPR) and the T variant of the G-703T polymorphism in the tryptophan hydroxylase-2 (TPH2) gene have previously been associated with amygdala hyperresponsivity to negative faces in healthy controls. We investigated the influence of these polymorphisms on amygdala responsiveness to angry faces in patients with social anxiety disorder (SAD) compared with healthy controls. METHODS: We used positron emission tomography with oxygen 15-labelled water to assess regional cerebral blood flow in 34 patients with SAD and 18 controls who viewed photographs of angry and neutral faces presented in counterbalanced order. We genotyped all participants with respect to the 5-HTTLPR and TPH2 polymorphisms. RESULTS: Patients with SAD and controls had increased left amygdala activation in response to angry compared with neutral faces. Genotype but not diagnosis explained a significant portion of the variance in amygdala responsiveness, the response being more pronounced in carriers of s and/or T alleles. LIMITATIONS: Our analyses were limited owing to the small sample and the fact that we were unable to match participants on genotype before enrollment. In addition, other imaging techniques not used in our study may have revealed additional effects of emotional stimuli. CONCLUSION: Amygdala responsiveness to angry faces was more strongly related to serotonergic polymorphisms than to diagnosis of SAD. Emotion activation studies comparing amygdala excitability in patient and control groups could benefit from taking variation in 5-HT-related genes into account.
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| 6. |
- Laukka, Petri, et al.
(författare)
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In a nervous voice : Acoustic analysis and perception of anxiety in social phobics' speech
- 2008
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Ingår i: Journal of nonverbal behavior. - : Springer Science and Business Media LLC. - 0191-5886 .- 1573-3653. ; 32:4, s. 195-214
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effects of anxiety on nonverbal aspects of speech using data collected in the framework of a large study of social phobia treatment. The speech of social phobics (N = 71) was recorded during an anxiogenic public speaking task both before and after treatment. The speech samples were analyzed with respect to various acoustic parameters related to pitch, loudness, voice quality, and temporal apsects of speech. The samples were further content-masked by low-pass filtering (which obscures the linguistic content of the speech but preserves nonverbal affective cues) and subjected to listening tests. Results showed that a decrease in experienced state anxiety after treatment was accompanied by corresponding decreases in a) several acoustic parameters (i.e., mean and maximum voice pitch, high-frequency components in the energy spectrum, and proportion of silent pauses), and b) listeners' perceived level of nervousness. Both speakers' self-ratings of state anxiety and listeners' ratings of perceived nervousness were further correlated with similar acoustic parameters. The results complement earlier studies on vocal affect expression which have been conducted on posed, rather than authentic, emotional speech.
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| 7. |
- Linnman, Clas, et al.
(författare)
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Chronic whiplash symptoms are related to altered regional cerebral blood flow in the resting state
- 2009
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Ingår i: European Journal of Pain. - : Wiley. - 1090-3801 .- 1532-2149. ; 13:1, s. 65-70
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Tidskriftsartikel (refereegranskat)abstract
- The neural pathogenic mechanisms involved in mediating chronic pain and whiplash associated disorders (WAD) after rear impact car collisions are largely unknown. This study's first objective was to compare resting state regional cerebral blood flow (rCBF) by means of positron emission tomography with (15)O labelled water in 21 WAD patients with 18 healthy, pain-free controls. A second objective was to investigate the relations between brain areas with altered rCBF to pain experience, somatic symptoms, posttraumatic stress symptoms and personality traits in the patient group. Patients had heightened resting rCBF bilaterally in the posterior parahippocampal and the posterior cingulate gyri, in the right thalamus and the right medial prefrontal gyrus as well as lowered tempero-occipital blood flow compared with healthy controls. The altered rCBF in the patient group was correlated to neck disability ratings. We thus suggest an involvement of the posterior cingulate, parahippocampal and medial prefrontal gyri in WAD and speculate that alterations in the resting state are linked to an increased self-relevant evaluation of pain and stress.
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| 8. |
- Michelgård, Åsa, et al.
(författare)
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Symptom provocation in specific phobia affects the substance P neurokinin-1 receptor systems
- 2007
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 61:8, s. 1002-1006
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Tidskriftsartikel (refereegranskat)abstract
- Background: Animal studies demonstrate that stress and negative affect enhance the release of the neuropeptide substance P (SP), which binds to the neurokinin 1 (NK1) receptor. This positron emission tomography (PET) study evaluated how the activity in the SP-NK1 receptor system in the amygdala was affected by fear provocation in subjects with specific phobia. Methods: Sixteen adult women with DSM-IV-defined specific phobia for either snakes or spiders but not both viewed pictures of feared and non-feared animals while being PET-scanned for 60 min with the highly specific NK1 receptor antagonist [11C]GR205171 as the labeled PET tracer. Results: The uptake of the labeled NK1 receptor antagonist was significantly reduced in the right amygdala during phobic stimulation. In the left amygdala no significant differences were found between phobic and non-phobic conditions. There was a negative correlation in the right, but not left, amygdala between subjective anxiety ratings and NK1 tracer binding. Conclusions: Fear provocation affects the SP-NK1 receptor system in the right amygdala. This reflects reduced NK1 receptor availability during fear and could mirror an increased release of endogenous substance P.
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| 9. |
- Syvänen, Stina, et al.
(författare)
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Predicting brain concentrations of drug using positron emission tomography and venous input : modeling of arterial-venous concentration differences
- 2006
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Ingår i: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 0031-6970 .- 1432-1041. ; 62:10, s. 839-848
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVEIn a positron emission tomography (PET) study, the concentrations of the labeled drug (radiotracer) are often different in arterial and venous plasma, especially immediately following administration. In a PET study, the transfer of the drug from plasma to brain is usually described using arterial plasma concentrations, whereas venous sampling is standard in clinical pharmacokinetic studies of new drug candidates. The purpose of the study was to demonstrate the modeling of brain drug kinetics based on PET data in combination with venous blood sampling and an arterio-venous transform (T(av)).METHODSBrain kinetics (C(br)) was described as the convolution of arterial plasma kinetics (C(ar)) with an arterial-to-brain impulse response function (T(br)). The arterial plasma kinetics was obtained as venous plasma kinetics (C(ve)) convolved with the inverse of the arterio-venous transform (T(av) (-1)). The brain kinetics was then given by C(br)=C(ve)*T(av) (-1)*T(br). This concept was applied on data from a clinical PET study in which both arterial and venous plasma sampling was done in parallel to PET measurement of brain drug kinetics. The predictions of the brain kinetics based on an arterial input were compared with predictions using a venous input with and without an arterio-venous transform.RESULTSThe venous based models for brain distribution, including a biexponential arterio-venous transform, performed comparably to models based on arterial data and better than venous based models without the transform. It was also shown that three different brain regions with different shaped concentration curves could be modeled with a common arterio-venous transform together with an individual brain distribution model.CONCLUSIONWe demonstrated the feasibility of modeling brain drug kinetics based on PET data in combination with venous blood sampling and an arterio-venous transform. Such a model can in turn be used for the calculation of brain kinetics resulting from an arbitrary administration mode by applying this model on venous plasma pharmacokinetics. This would be an important advantage in the development of drugs acting in the brain, and in other circumstances when the effect is likely to be closer related to the brain than the plasma concentration.
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| 10. |
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