Home About us Contact
|
Home About us Contact | ||
|
|
||
Double-blind Design (double-blind + design)
Selected AbstractsCognitive effects of a Ginkgo biloba/vinpocetine compound in normal adults: systematic assessment of perception, attention and memoryHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 5 2001John Polich Abstract A computerized test battery was used in a double-blind design to assess the cognitive effects of a nutrient compound containing Ginkgo biloba in 24 normal adults. Ten tasks (perceptual, attention and short-term memory) were presented in a standardized manner designed to maximize performance, with substantial pre-test practice employed to minimize response variability. Subjects were given either placebo or Ginkgo biloba extract capsules to consume for 14 days, after which they performed all tasks twice. They then received the other condition, and after 14 days completed the final test session. Response time and error rate stabilized after pre-test practice. A ,working memory capacity' paradigm demonstrated a reliable 50,ms response time decrease between the placebo and Ginkgo biloba testing, suggesting that Ginkgo biloba speeds short-term working memory processing in normal adults. Copyright © 2001 John Wiley & Sons, Ltd. [source] ALDH2 Status, Alcohol Expectancies, and Alcohol Response: Preliminary Evidence for a Mediation ModelALCOHOLISM, Issue 11 2001Denis M. McCarthy Background: A genetic variant in the alcohol-metabolizing enzyme (aldehyde dehydrogenase;ALDH2*2 allele), common in individuals of Asian heritage, has been associated with both physiologic response to alcohol and alcohol consumption. Prior research has also demonstrated that those with ALDH2*2 alleles have lower positive alcohol expectancies than those without these alleles. This preliminary study was designed to test whether the level of response to alcohol is the mechanism by which ALDH2 status may affect alcohol expectancies. Methods: Data were collected from 32 Asian American college students (14 women and 18 men). By use of a randomized, double-blind design, participants were administered oral placebo and alcohol at separate laboratory sessions. Data included blood tests to establish ALDH2 status, questionnaire measures of demographic information and alcohol expectancy, and several physiologic measures collected after placebo and alcohol administration. Results: ALDH2 status was related to alcohol response measures for both men and women. ALDH2 status was also related to tension reduction expectancies for women and to expectancies for cognitive behavioral impairment for men. In the male sample, the ALDH2/expectancy relationship was fully explained by the level of response to alcohol. Conclusions: These results represent a first step in understanding the mechanisms by which genetic factors, such as ALDH2 status, can affect alcohol-related learning. [source] Single-dose dexmedetomidine attenuates airway and circulatory reflexes during extubationACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2005G. Guler Background:, The alpha agonist dexmedetomidine, a sedative and analgesic, reduces heart rate and blood pressure dose-dependently. We investigated whether it also has the ability to attenuate airway and circulatory reflexes during emergence from anaesthesia. Methods:, Sixty ASA I,III patients received a standard anaesthetic. Five minutes before the end of surgery, they were randomly allocated to receive either dexmedetomidine 0.5 µg/kg (Group D) (n = 30) or saline placebo (Group P) (n = 30) intravenously (i.v.) over 60 s in a double-blind design. The blinded anaesthetist awoke all the patients, and the number of coughs per patient was continuously monitored for 15 min after extubation; coughing was evaluated on a 4-point scale. Any laryngospasm, bronchospasm or desaturation was recorded. Heart rate (HR) and systolic and diastolic blood pressure (SAP, DAP) were measured before, during and after tracheal extubation. The time from tracheal extubation and emergence from anaesthesia were recorded. Results:, Median coughing scores were 1 (1,3) in Group D and 2 (1,4) in Group P (P < 0.05), but there were no differences between the groups in the incidence of breath holding or desaturation. HR, SAP and DAP increased at extubation in both groups (P < 0.05), but the increase was less significant with dexmedetomidine. The time from tracheal extubation and emergence from anaesthesia were similar in both groups. Conclusion:, These findings suggest that a single-dose bolus injection of dexmedetomidine before tracheal extubation attenuates airway-circulatory reflexes during extubation. [source] Acute cortisol effects on immediate free recall and recognition of nouns depend on stimulus valencePSYCHOPHYSIOLOGY, Issue 2 2003Mattie Tops Abstract The present study investigated the acute effects of cortisol administration in normal healthy male volunteers on immediate free recall and recognition of pleasant, unpleasant, and neutral nouns using a between-subjects double-blind design. Two hours after cortisol (10 mg) or placebo administration, impaired recall and recognition of neutral and pleasant words was found in the treatment group, whereas recall and recognition of unpleasant words was similar in both groups. The interaction between treatment and stimulus valence was not mediated by "semantic cohesion," nor does it seem to have been mediated by stimulus arousal. Cortisol did not change mood. The changes with cortisol in recall and recognition of pleasant and unpleasant words parallel those found in depression, a condition that is often accompanied by elevated basal cortisol levels. [source] Comparison of clozapine and haloperidol on some autonomic and psychomotor functions, and on serum prolactin concentration, in healthy subjectsBRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 3 2001J. L. Pretorius Aims To compare the autonomic, neuroendocrine and psychomotor effects of single doses of the ,atypical' antipsychotic clozapine and the ,classical' antipsychotic haloperidol, in healthy male volunteers. Methods Clozapine (50 mg), haloperidol (3 mg) and placebo were administered to 12 healthy male volunteers at weekly intervals, according to a balanced double-blind design. Resting pupil diameter, salivary output, heart rate, blood pressure, plasma prolactin concentration, critical flicker fusion frequency and subjective ,alertness', ,contentedness' and ,anxiety' were measured at baseline and 2, 3, 4 and 5 h after drug ingestion. Data were analysed by analysis of variance with individual comparisons (Dunnett's test) with a significance criterion of P < 0.05. Results Significant treatment effects (difference from placebo [mean, 95% CI] 5 h after drug ingestion) were as follows: clozapine reduced pupil diameter (mm; ,3.02 [,3.56, ,2.47]), salivary output (g; ,0.34 [,0.60, ,0.08]), mean arterial blood pressure (mm Hg; ,8.7 [,14.3, ,3.1]), critical flicker fusion frequency (Hz; ,3.26 [,3.94, ,2.58]), and subjectively-rated ,alertness' (mm; ,20.94 [,29.21, ,12.67]) and ,contentedness' (mm; ,12.98 [,17.90, ,8.06]), whereas haloperidol increased prolactin concentration (mU l,1; 301.3 [196.7, 405.8]) and caused small reductions in pupil diameter (mm; ,0.68 [,1.23, ,0.14]), mean arterial blood pressure (mm Hg; ,7.0 [,12.6, ,1.4]) and critical flicker fusion frequency (Hz; ,1.15 [,1.83, ,0.47]). Conclusions The effects of the antipsychotics are in agreement with their receptor binding profiles: ,1 -adrenoceptor blockade by clozapine may contribute to reductions in pupil diameter, salivation, mean arterial blood pressure and sedation, and muscarinic cholinoceptor blockade by the drug may underlie the reduction in salivation. Conversely, D2 dopamine receptor blockade by haloperidol is likely to be responsible for the increase in prolactin secretion evoked by the drug. [source] | ||||||||||