Biomedical subjects

Oleg V Tcheremissine

Publications and source records attributed to Oleg V Tcheremissine.

12 recordsLinked to original sources

PubMed2006

Response perseveration and adaptation in heavy marijuana-smoking adolescents.

The present study examined two behavioral processes - response perseveration and response adaptation - in adolescents who were heavy marijuana smokers and control adolescents. Testing took place in a controlled laboratory setting, using customized software and either a computer keyboard or a custom built response panel for response input. Adolescents age 14-18 were recruited into a heavy smoking (near daily) group (N=22) or a control group (N=31) with <15 lifetime uses of marijuana and no history of substance abuse or dependence. Marijuana use was verified by daily quantification of urinary cannabinoids and self-reports. Participants completed laboratory tasks designed to measure response perseveration (Wisconsin Card Sort Task, WCST) and response adaptation (concurrent variable-ratio reinforcement schedule with changing contingencies). Data were analyzed via ANOVA, controlling for multiple factors including: gender, age, nicotine use, presence of conduct disorder, and subscales of the Youth Self Report. After controlling for these compared to controls marijuana-using participants made significantly more perseverative and total errors on the WCST and showed significantly impaired (e.g., less adaptive) response allocation to the changing reinforcement contingencies on the concurrent-reinforcement task. Within the constraints of the study's limitations in controlling for alternative sources of between-subject variability, the data suggest that individuals who regularly smoke marijuana during adolescence show measurable perturbations in important basic behavioral processes. The data are also consistent with a previous laboratory study demonstrating reduced motivation in marijuana-smoking adolescents versus controls [Lane, S.D., Cherek, D.R., Pietras, C.J., and Steinberg, J.L. (2005). Performance of heavy marijuana-smoking adolescents on a laboratory measure of motivation. Addictive Behaviors, 30, 815-828].

Adaptation, Psychological↗

PubMed2006

Effects of marijuana on temporal discriminations in humans.

Marijuana has been reported to alter the discrimination of time. The present study used a psychophysical approach to examine the effects of marijuana on temporal discrimination in humans. Research participants were required to push one of two buttons depending on the duration of a conditional stimulus (a blue square on a computer monitor). Correct choices ('C' button after a 2-s stimulus; 'A' button after a 4-s stimulus) resulted in an increase in session earnings of 0.12 dollars. Intermediate durations (probe stimuli between 2 and 4 s) were also presented. Psychophysical functions relating the probability of judging a duration as 'long' (4 s) as a function of actual stimulus durations were characterized by a logistic function fitted to the data. Administration of both low (1/2 placebo and 1/2 2.2% Delta (9)-tetrahydrocannabinol cigarette) and high (3.89% Delta(9)-tetrahydrocannabinol) potency marijuana cigarettes produced a bias of judging intervals as long, consistent with an interpretation that subjective time passes more quickly when an individual is intoxicated by marijuana. Deliberation time, operationally defined as response latency, peaked on trials with sample durations that corresponded to the measure of central tendency, and shifted in a similar manner after marijuana administration. The data are consistent with other studies on the effects of marijuana on time estimation.

Adult↗

PubMed2006

Pharmacological aspects of the treatment of conduct disorder in children and adolescents.

In recent years, the rates of psychosocial disorders in children and adolescents have increased, with behavioural manifestations of conduct disorder being one of the most common reasons for referrals to community psychiatrists. Childhood conduct problems are associated with a variety of psychiatric disorders in adult life that extend beyond antisocial behaviour. An increased awareness of the costs of conduct disorder to individuals, families and society has led to advancements in the pharmacological and nonpharmacological therapeutic modalities for this disorder. Despite this, patients with conduct disorder are difficult to treat as the patterns of maladaptive behaviours they exhibit are diverse and can vary as a function of age and sex. A multidisciplinary approach to the treatment of conduct disorder, which includes behavioural parent training, interpersonal skills training, family therapy and the use of psychotropic agents targeted at a particular cluster of symptoms, can increase the overall effectiveness of each of the applied interventions. Aggression, hyperactivity, impulsivity and mood symptoms are the most sensitive proximal targets. Evidence suggests that antipsychotics, antidepressants, mood stabilisers, antiepileptic drugs, stimulants and adrenergic drugs can be well tolerated and effective therapeutic options for individuals with conduct disorder and comorbid psychiatric conditions. However, the most successful therapeutic outcomes are likely to be achieved by combining the current advances in psychopharmacology with behavioural and psychosocial interventions, aimed at modifying the excessive patterns of maladaptive behaviours observed in conduct disorder.

Adolescent↗

PubMed2005

Acute effects of alprazolam on risky decision making in humans.

RATIONALE: GABA-A receptor ligands, including benzodiapines, may induce disinhibitory effects that increase the probability of risky decision making. To date, few laboratory studies have examined the acute, dose-related effects of benzodiazepines on human risk-taking behavior. Recent data indicate that in the United States alprazolam is the benzodiazepine most frequently misused for recreational purposes. OBJECTIVES: The present study was designed to demonstrate a dose-response relationship between acute alprazolam administration and human risk taking. Furthermore, this investigation sought to examine: (1) the behavioral mechanisms that may be involved in changes in the probability of risky decision making related to alprazolam administration and (2) risk seeking-related personality variables that may predict drug effects on risk taking. METHODS: Using a laboratory measure of risk taking designed to address acute drug effects, 16 adults were administered placebo, 0.5, 1.0, and 2.0 mg alprazolam in a within-subject repeated-measures design. The risk-taking task presented subjects with a choice between two response options operationally defined as risky and nonrisky. Data analyses examined subjective effects, response rates, distribution of choices between the risky and nonrisky option, trial-by-trial response probabilities, and personality correlates related to drug effects at the 2.0-mg dose. RESULTS: Alprazolam administration produced dose-related changes in subjective effects, response rates, and, most importantly, dose-dependently increased selection of the risky response option. The 2.0-mg dose increased the probability of making consecutive risky responses following a gain on the risky response option. Increases at 2.0 mg were related to a combination of personality scales that included high venturesomeness and novelty seeking and low harm avoidance. CONCLUSIONS: Alprazolam administration produced increases in human risk taking under laboratory conditions. In union with previous studies, the observed shift in trial-by-trial response probabilities suggests that sensitivity to consequences (e.g., oversensitivity to recent rewards) may be an important mechanism in the psychopharmacology of risky decision making. Additionally, risk-seeking personality traits may be predictive of acute drug effects on risk-taking behavior.

Administration, Oral↗

PubMed2005

Acute marijuana effects on human risk taking.

Previous studies have established a relationship between marijuana use and risky behavior in natural settings. A limited number of laboratory investigations of marijuana effects on human risk taking have been conducted. The present study was designed to examine the acute effects of smoked marijuana on human risk taking, and to identify behavioral mechanisms that may be involved in drug-induced changes in the probability of risky behavior. Using a laboratory measure of risk taking designed to address acute drug effects, 10 adults were administered placebo cigarettes and three doses of active marijuana cigarettes (half placebo and half 1.77%; 1.77%; and 3.58% Delta9-THC) in a within-subject repeated-measures experimental design. The risk-taking task presented subjects with a choice between two response options operationally defined as risky and nonrisky. Data analyses examined cardiovascular and subjective effects, response rates, distribution of choices between the risky and nonrisky option, and first-order transition probabilities of trial-by-trial data. The 3.58% THC dose increased selection of the risky response option, and uniquely shifted response probabilities following both winning and losing outcomes following selection of the risky option. Acute marijuana administration thereby produced measurable changes in risky decision making under laboratory conditions. Consistent with previous risk-taking studies, shifts in trial-by-trial response probabilities at the highest dose suggested a change in sensitivity to both reinforced and losing risky outcomes. Altered sensitivity to consequences may be a mechanism in drug-induced changes in risk taking. Possible neurobiological sites of action related to THC are discussed.

Adult↗

PubMed2005

Individual differences in aggressive responding to intravenous flumazenil administration in adult male parolees.

Nonhuman and human studies have shown that benzodiazepine (BZD) receptor agonists can modify aggressive behaviour. However, it is unknown whether flumazenil, a BZD receptor antagonist, enhances or inhibits aggressive behaviour. The present study was designed to investigate the effects of acute administrations of flumazenil on aggressive responding in adult humans. Six adult males with histories of childhood conduct disorder (DSM IV R) participated in experimental sessions. Aggression was measured using the Point Subtraction Aggression Paradigm (PSAP; Cherek 1992), which provided subjects with aggressive and monetary-reinforced response options. Acute doses of flumazenil (2 and 3mg) did not produce statistically significant changes in either monetary-reinforced responding or aggressive responding. The analysis of individual subjects data revealed that aggressive responses varied across subjects. The results are discussed in terms of individual differences based on the previous history of BZD abuse. Additional laboratory research is needed to better clarify the behavioural mechanisms by which BZD receptor antagonists modify human aggressive responding.

Adult↗

PubMed2005

Pharmacotherapy of postpartum depression: current practice and future directions.

Postpartum depression has well-documented consequences for the mother, child, family and society as a whole. Despite an increasing awareness of postpartum depression, it often remains unrecognised by clinicians and poorly understood by researchers. The current trend is undoubtedly a result of the complex nature of depressive disorders accentuated by difficulties with the current classification schemas. Systematic prospective data on the onset of depression during pregnancy and the postpartum period, as well as on the risk of relapse during these periods in women with previous histories of mood and anxiety disorders, are limited. This article reviews clinically relevant outcomes and current trends in the pharmacotherapy of postpartum depression from selected clinical trials. Critical issues of the neurobiology and phenomenology of postpartum depression are raised, and future directions of the pharmacological treatments of postpartum depression are examined.

Antidepressive Agents↗

PubMed2005

Marijuana effects on human forgetting functions.

It has long been known that acute marijuana administration impairs working memory (e.g., the discrimination of stimuli separated by a delay). The determination of which of the individual components of memory are altered by marijuana is an unresolved problem. Previous human studies did not use test protocols that allowed for the determination of delay-independent (initial discrimination) from delay-dependent (forgetting or retrieval) components of memory. Using methods developed in the experimental analysis of behavior and signal detection theory, we tested the acute effects of smoked marijuana on forgetting functions in 5 humans. Immediately after smoking placebo, a low dose, or a high dose of marijuana (varying in delta9-THC content), subjects completed delayed match-to-sample testing that included a range of retention intervals within each test session (0.5, 4, 12, and 24 s). Performances (discriminability) at each dose were plotted as forgetting functions, as described and developed by White and colleagues (White, 1985; White & Ruske, 2002). For all 5 subjects, both delta9-THC doses impaired delay-dependent discrimination but not delay-independent discrimination. The outcome is consistent with current nonhuman studies examining the role of the cannabinoid system on delayed matching procedures, and the data help illuminate one behavioral mechanism through which marijuana alters memory performance.

Adult↗

PubMed2004

Psychopharmacology of conduct disorder: current progress and future directions.

Behavioural manifestations of conduct disorder (CD) among children and adolescents are one of the most common referrals to community psychiatrists. Patients with CD are difficult to treat. The patterns of maladaptive behaviours they exhibit are diverse and can vary as a function of age and gender. Although different pharmacological interventions have been reported as potentially promising options in the treatment of CD, no medication has yet received a formal approval from the licensure authorities, either in the US or Europe. This article reviews efficacy results and associated adverse effects from selected clinical trials that have the strongest outcome evidence for the treatment of CD in children and adolescents. Critical issues in the effectiveness of the evidence-based pharmacotherapy for CD are raised and future directions of the psychopharmacology of CD are examined.

Comorbidity↗

PubMed2003

Alcohol effects on human risk taking.

RATIONALE: Despite a well-established relationship between alcohol and risky behavior in the natural environment, laboratory investigations have not reliably shown acute alcohol effects on human risk-taking. OBJECTIVES: The present study was designed to demonstrate a dose-response relationship between acute alcohol administration and human risk taking. Further, this investigation sought to delineate behavioral mechanisms that may be involved in alcohol-induced changes in the probability of risky behavior. METHODS: Using a laboratory measure of risk taking designed to address acute drug effects, 16 adults were administered placebo, 0.2, 0.4, and 0.8 g/kg alcohol in a within-subject repeated measures experimental design. The risk-taking task presented subjects with a choice between two response options operationally defined as risky and non-risky. Data analyses examined: breath alcohol level (BAL), subjective effects, response rates, distribution of choices between the risky and non-risky option, and trial-by-trial probabilities of making losing and winning risky responses. RESULTS: The alcohol administration produced the expected changes in BAL, subjective effects, and response rate. Alcohol dose-dependently increased selection of the risky response option, and at the 0.8 g/kg dose, increased the probability of making consecutive losing risky responses following a gain on the risky response option. CONCLUSIONS: Acute alcohol administration can produce measurable changes in human risk-taking under laboratory conditions. Shifts in trial-by-trial response probabilities suggest insensitivity to past rewards and more recent losses when intoxicated, an outcome consistent with previous studies. This shift in sensitivity to consequences is a possible mechanism in alcohol-induced changes in risk taking.

Adult↗

PubMed2003

Effects of methylphenidate on impulsive choice in adult humans.

RATIONALE: Several studies with nonhumans and humans have shown that stimulants decrease impulsive choices on delay-to-reinforcement (self-control) procedures. Little is known, however, about the effects of the stimulant methylphenidate on choice for delayed reinforcers in humans. OBJECTIVES: The present study was designed to investigate the effects of acute methylphenidate administrations on impulsive responding in adult humans on a delay-to-reinforcement task. METHODS: Eleven adult males with a history of criminal behavior but no history of attention-deficit hyperactivity disorder (ADHD) participated. Impulsive responding was measured using an adjusting-delay procedure in which subjects were presented with repeated choices between a small amount of money delivered after a short delay and a larger amount of money delivered after a delay that adjusted as a function of previous choices. Subjects were exposed to four experimental sessions each day of participation and 60 min prior to the first daily session received placebo or 0.15, 0.30, or 0.60 mg/kg methylphenidate. Stable choice patterns were re-established between each methylphenidate dose. RESULTS: Individuals differed in their sensitivity to methylphenidate, but in over half of the subjects methylphenidate decreased impulsive (i.e., increased the number of self-control choices) and increased the delay to the large reinforcer. The largest increases in self-control choices tended to occur at the 0.30-mg/kg and 0.60-mg/kg doses, and the effects often persisted across multiple daily sessions. In six subjects, under at least one methylphenidate dose, the number of impulsive choices decreased to zero. CONCLUSIONS: Acute methylphenidate administrations tended to decrease the number of impulsive choices in adult humans on an adjusting-delay procedure, although there were substantial individual differences in the sensitivity of choice to methylphenidate. In no case, however, did methylphenidate increase impulsive choices. These results are consistent with several recent laboratory studies with nonhumans and humans showing that stimulants increase preference for large, delayed reinforcers.

Adolescent↗

PubMed2003

Acute effects of gabapentin on laboratory measures of aggressive and escape responses of adult parolees with and without a history of conduct disorder.

RATIONALE: The possible role of GABA in human aggression was evaluated by administering gabapentin to subjects with and without a history of conduct disorder and comparing the effects on laboratory measures of aggression and escape. METHODS: Eighteen male and two female subjects with a history of criminal behavior participated in experimental sessions, which measured aggressive and escape responses. Ten subjects had a history of childhood conduct disorder (CD+) and ten subjects with no history (non-CD controls). Aggression was measured using the Point Subtraction Aggression Paradigm (PSAP), which provided subjects aggressive, escape and monetary reinforced response options. RESULTS: Acute doses (200, 400 and 800 mg) of gabapentin had similar effects on aggressive responses among CD+ subjects compared to non-CD control subjects. Aggressive responses of CD+ and non-CD control subjects increased at lower gabapentin doses, and decreased at the highest 800 mg gabapentin dose. Gabapentin increased escape responses for both CD+ and non-CD controls CD- subjects at the lowest dose, but then produced dose-related decreases at the two higher doses in both groups. No changes in monetary reinforced responses were observed, indicative of no CNS stimulation or sedation. CONCLUSIONS: Gabapentin produced similar bitonic effects upon aggressive and escape responses in subjects with and without a history of childhood conduct disorder. This is in marked contrast to prior differential effects of baclofen on aggressive responses between CD+ and non-CD control subjects in a previous study.

Acetates↗