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Challenge Paradigm (challenge + paradigm)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Sumatriptan challenge in bipolar patients with and without migraine: a neuroendocrine study of 5-HT1D receptor function.

HEADACHE, Issue 3 2003
T Mahmood
Int Clin Psychopharmacol. 2002 Jan;17(1):33-36 An association between bipolar disorder and migraine has been lately recognized and an abnormality of central serotonergic function is suggested as the underlying neurophysiological disturbance. To examine the role of serotonin in bipolar disorder and migraine, we used the neuroendocrine challenge paradigm, and we chose sumatriptan, a 5HT1D agonist, as the pharmacological probe. We studied nine bipolar patients with migraine, nine bipolar patients without it, seven migraine patients, and nine matched normal controls. A post-hoc analysis showed subsensitivity of serotonergic function, reflected in a blunted growth hormone response to sumatriptan challenge in bipolar patients who also suffered from migraine. Comment: Given regulatory and labelling concerns about the potential for triptans to provoke serotonin syndrome, the apparent down-regulation of serotonergic function in patients with bipolar disorder may suggest cause for cautious optimism and encourage future study of triptans in these patients to establish true causality or otherwise. A prospective trial of sumatriptan injectable identified 1700 patients who repetitively used the triptan and were concomitantly on selective serotonin reuptake inhibitor (SSRI) medication. No serotonin syndrome was reported in any patient (Putnam GP, O'Quinn S, Bolden-Watson CP, Davis RL, Gutterman DL, Fox AW. Migraine polypharmacy and the tolerability of sumatriptan: a large-scale, prospective study. Cephalalgia. 1999;19:668-675). Since SSRIs can rarely induce serotonin syndrome alone, there is a significant difficulty in establishing a risk of coadministration. DSM and SJT [source]

Dynamic Assessment of Abnormalities in Central Pain Transmission and Modulation in Tension-type Headache Sufferers

HEADACHE, Issue 2 2000
Jonathan D. Neufeld PhD
Objective.,To examine and compare central pain processing and modulation in young tension-type headache sufferers with that of matched healthy controls using an induced headache "challenge" paradigm. Background.,Recent research has suggested that abnormalities in central pain processing and descending pain modulation may contribute to chronic tension-type headache. These abnormalities, if they contribute to headache pathogenesis, should be present in young adult tension-type headache sufferers. Recent research using static measures of physiological variables, such as muscle tenderness and exteroceptive suppression, has identified chronic muscle tenderness as a characteristic of young tension-type headache sufferers, but other central nervous system functional abnormalities may require a dynamic "challenge" to be observed. Methods.,Twenty-four young women meeting the International Headache Society diagnostic criteria for tension-type headache (headache-prone) and a matched group of 24 healthy women who reported fewer than 10 problem headaches per year (control) participated in a double-blind, placebo-controlled, crossover study. Subjects completed jaw clenching and a placebo condition on different days in counterbalanced order. Pericranial muscle tenderness, pressure-pain thresholds on the temporalis, and exteroceptive suppression periods were assessed before and after each procedure. Head pain was recorded for 12 to16 hours following each condition. Results.,Headache-prone subjects were more likely than controls to experience headaches after both the jaw clenching and placebo procedures, but neither group was significantly more likely to experience headaches following jaw clenching than placebo. In pretreatment measurements, headache-prone subjects exhibited greater muscle tenderness than controls, but pressure-pain detection thresholds and exteroceptive suppression periods did not differ in the two groups. Control subjects showed increases in muscle tenderness and exteroceptive suppression periods following both the clenching and placebo procedures, whereas headache-prone subjects exhibited no significant changes in any of the physiological measures following either experimental manipulation. Conclusions.,These results confirm previous findings indicating abnormally high pericranial muscle tenderness in young tension headache sufferers even in the headache-free state. In addition, the results suggest that the development of headaches following noxious stimulation is more strongly related to headache proneness and associated abnormalities in central pain transmission or modulation (indexed by pericranial muscle tenderness and exteroceptive suppression responses) than muscle strain induced by jaw clenching. [source]

Effects of Alcohol on Performance on a Distraction Task During Simulated Driving

ALCOHOLISM, Issue 4 2009
Allyssa J. Allen
Background:, Prior studies report that accidents involving intoxicated drivers are more likely to occur during performance of secondary tasks. We studied this phenomenon, using a dual-task paradigm, involving performance of a visual oddball (VO) task while driving in an alcohol challenge paradigm. Previous functional MRI (fMRI) studies of the VO task have shown activation in the anterior cingulate, hippocampus, and prefrontal cortex. Thus, we predicted dose-dependent decreases in activation of these areas during VO performance. Methods:, Forty healthy social drinkers were administered 3 different doses of alcohol, individually tailored to their gender and weight. Participants performed a VO task while operating a virtual reality driving simulator in a 3T fMRI scanner. Results:, Analysis showed a dose-dependent linear decrease in Blood Oxygen Level Dependent activation during task performance, primarily in hippocampus, anterior cingulate, and dorsolateral prefrontal areas, with the least activation occurring during the high dose. Behavioral analysis showed a dose-dependent linear increase in reaction time, with no effects associated with either correct hits or false alarms. In all dose conditions, driving speed decreased significantly after a VO stimulus. However, at the high dose this decrease was significantly less. Passenger-side line crossings significantly increased at the high dose. Conclusions:, These results suggest that driving impairment during secondary task performance may be associated with alcohol-related effects on the above brain regions, which are involved with attentional processing/decision-making. Drivers with high blood alcohol concentrations may be less able to orient or detect novel or sudden stimuli during driving. [source]

Hypothalamic Function in Response to 2-Deoxy- d -Glucose in Long-Term Abstinent Alcoholics

ALCOHOLISM, Issue 5 2001
John C. Umhau
Background: The body adapts to diverse stressful stimuli with a response characterized by activation of the hypothalamic-pituitary-adrenal (HPA) axis. Chronic alcohol consumption can cause changes in the function of this neuroendocrine system. Although many studies have examined this phenomenon in drinking and recently sober alcoholics, few studies have examined HPA axis function in long-term sober alcoholics. Methods: To characterize HPA axis function in long-term sober alcoholics, we used a challenge paradigm with 2-deoxy-d-glucose (2-DG). An infusion of 2-DG (a nonmetabolizable glucose analog) induces a well-characterized stress response. In a previous study, our laboratory found an exaggerated corticotropin and cortisol response in alcoholics abstinent 3 weeks; in this investigation we compared the effects of an infusion of 2-DG on 19 healthy volunteers and 20 community-living alcoholics who had been abstinent more than 6 months. Results: In contrast to the previous study, long-term sober alcoholics did not have an exaggerated corticotropin and cortisol response after 2-DG. Conclusions: Previously observed abnormalities in cortisol regulation in 3-week-sober alcoholics may be related to the acute effects of recent alcohol consumption and withdrawal. Future investigations into the metabolic function of alcoholics, particularly investigations involving the HPA system, should consider the possibility that normalization may not occur until long-term abstinence has been achieved. [source]

Subjective Response to Alcohol: A Critical Review of the Literature

ALCOHOLISM, Issue 3 2010
Meghan E. Morean
Background:, Subjective response to alcohol (SR), which reflects individual differences in sensitivity to the pharmacological effects of alcohol, may be an important endophenotype in understanding genetic influences on drinking behavior and alcohol use disorders (AUDs). SR predicts alcohol use and problems and has been found to differ by a range of established risk factors for the development of AUDs (e.g., family history of alcoholism). The exact pattern of SR associated with increased risk for alcohol problems, however, remains unclear. The Low Level of Response Model (LLR) suggests that high-risk individuals experience decreased sensitivity to the full range of alcohol effects, while the Differentiator Model (DM) asserts that high risks status is associated with increased sensitivity to alcohol's positive effects but decreased sensitivity to negative effects. Aims:, The current paper (1) reviews two prominent models of subjective response, (2) reviews extant laboratory-based research on subjective response, (3) highlights remaining gaps in our understanding and assessment of subjective response, and (4) encourages collaborative efforts to address these methodological and conceptual concerns. Methods:, This paper reviews studies which employed placebo-controlled and non-placebo-controlled alcohol challenge paradigms to assess a range of alcohol effects including impairment, stimulation, and sedation. Results:, The research literature provides at least partial support for both the LLR and DM models. High-risk individuals have been shown to have a reduced response to alcohol with respect to sedative or impairing effects, particularly on the descending limb of the blood alcohol curve (BAC). There is also evidence that ascending limb stimulant effects are more pronounced or operate differently for high-risk individuals. Discussion:, Despite commendable advances in SR research, important questions remain unanswered. Inconsistent results across studies may be attributable to a combination of an inadequate understanding of the underlying construct and methodological differences across studies (e.g., number and timing of assessments across the BAC, inclusion of a placebo condition). With respect to the underlying construct, existing measures fail to adequately distinguish between cognitive/behavioral impairment and sedation, aspects of which may be perceived positively (e.g., anxiolysis) due to their ability to act as negative reinforcers. Conclusions:, Addressing the concerns raised by the current review will be integral to making meaningful scientific progress in the field of subjective response. [source]