Altered Mental Status at High Altitude.

Intrathecal baclofen pumps are commonly used in pediatric patients with spastic cerebral palsy. Baclofen binds to γ-aminobutyric acid receptors to inhibit both monosynaptic and polysynaptic reflexes at the spinal cord level. The blockade stops the release of excitatory transmitters and thereby decreases muscle contraction. It is commonly used for lower limb spasticity and has been shown to improve postural ability and functional status. The US Food and Drug Administration has approved baclofen for the treatment of spasticity of cerebral or spinal origin in adult and pediatric patients 4 years or older. Various complications of baclofen pumps are described in the literature. Immediately after surgery, problems from infection can arise and range from superficial skin infections to meningitis and bacteremia. Another early complication includes cerebrospinal fluid leak that can be observed by notable swelling beneath the lumbar incision. Additional problems that arise later are usually from the mechanics of the pump and catheter. Pump-related complications include failure, migration, and flipping. Catheter-related complications include disconnection, occlusion, fracture, or kink. Most of these complications typically lead to baclofen withdrawal, although there are a few case reports of overdose due to mechanical causes. Here we describe 2 cases of individuals experiencing complications of excessive baclofen exposure after significant changes in the atmospheric pressure due to travel involving ambient altitude change. These cases reflect the need to discuss this potential complication with families and patients with baclofen pumps before travel to high elevations.

Impacto das drogas na saúde física e mental de dependentes químicos / Drug use impact in drug addicts' physical and mental health

Pesquisa qualitativa e exploratória -desenvolvida em 2012 e 2013 -em uma unidade de reabilitação para dependentes químicos no Paraná, com objetivo de verificar o impacto do uso de drogas na saúde física e mental do dependente químico. Foram entrevistados vinte dependentes químicos em tratamento. Os dados foram coletados mediante entrevista semiestruturada e tratados com a técnica de análise categorial temática. Os resultados demonstraram impactos na condição física do dependente químico relacionados à intoxicaçãopor drogas, estado de abstinência, alterações de alimentação, sono, higiene e aparência pessoal. Em relação ao impacto das drogas na saúde mental, os resultados apontaram a presença de comorbidades psiquiátricas, como: esquizofrenia e transtorno afetivo bipolar, bem como alterações de pensamento, percepção, memória, cognição e comportamento. Conclui-se que as drogas ocasionam graves impactos na saúde física e mental dos dependentes químicos a partir de consequências nocivas na condição física, no autocuidado, no pensamento, na cognição e no comportamento.

This is a qualitative study of exploratory method, developedin2012 and 2013,in a rehab unity to drug addicts, Paraná, Curitiba, Brazil, its aim is verify the drug use impact in addicts' physical and mental health. Twenty drug addicts in treatment were interviewed.Data collected by through of semi-structured interviews andprocessed using the categorical thematic analysis.The results showed impacts on physical medical condition related to drug poisoning, the state of abstinence, changes on feed, sleep, rest, hygiene and personal appearance.Regarding the impact of substance abuse in mental health, the results indicated the presence of psychiatric comorbidies as schizophrenia and bipolar affective disorder, thought changes, perception, memory and cognition, also behavioral changes. As conclusion, drugs are responsible for huge impacts in addicts' physical and mental health considering the harmful consequences in the physical conditions, self-care, thought, cognition and in the behavior.

Cannabis and creativity: highly potent cannabis impairs divergent thinking in regular cannabis users.

RATIONALE: Cannabis users often claim that cannabis has the potential to enhance their creativity. Research suggests that aspects of creative performance might be improved when intoxicated with cannabis; however, the evidence is not conclusive. OBJECTIVE: The aim of this study was to investigate the acute effects of cannabis on creativity. METHODS: We examined the effects of administering a low (5.5 mg delta-9-tetrahydrocannabinol [THC]) or high (22 mg THC) dose of vaporized cannabis vs. placebo on creativity tasks tapping into divergent (Alternate Uses Task) and convergent (Remote Associates Task) thinking, in a population of regular cannabis users. The study used a randomized, double-blind, between-groups design. RESULTS: Participants in the high-dose group (n = 18) displayed significantly worse performance on the divergent thinking task, compared to individuals in both the low-dose (n = 18) and placebo (n = 18) groups. CONCLUSIONS: The findings suggest that cannabis with low potency does not have any impact on creativity, while highly potent cannabis actually impairs divergent thinking.

Beta-blockers may reduce intrusive thoughts in newly diagnosed cancer patients.

OBJECTIVE: A cancer diagnosis provokes significant levels of emotional distress, with intrusive thoughts being the most common manifestation among breast cancer survivors. Cancer-related intrusive thoughts can take the form of emotional memories, flashbacks, nightmares, and intrusive images. Emotional arousal after a severe life stressor prolongs adrenergic activation, which in turn may increase risk for post-traumatic symptomatology. However, antihypertensive beta-blockers block adrenergic activation and are known to reduce traumatic memories and related psychological distress. Thus, the current study examined the association between beta-blocker use and the severity of cancer-related intrusive thoughts and related symptoms following a cancer diagnosis. METHODS: The 174 breast and 36 female colorectal cancer patients who had recently undergone diagnostic screening or biopsy included 39 beta-blocker users and 171 non-users. Prior to any cancer treatment including surgery, participants completed questionnaires that included the Impact of Events Scale and the Center for Epidemiological Studies Depression Scale. Analyses controlled for age, education, cancer stage, cancer type, days since diagnosis, marital status, depression, and comorbidities. RESULTS: Although the high rates of cancer-related distress in this sample were similar to those of other studies with recently diagnosed patients, beta-blocker users endorsed 32% fewer cancer-related intrusive thoughts than non-users. CONCLUSIONS: Recently diagnosed cancer patients using beta-blockers reported less cancer-related psychological distress. These results suggest that beta-blocker use may benefit cancer patients' psychological adjustment following diagnosis, and provide a promising direction for future investigations on the pharmacological benefits of beta-blockers for cancer-related distress.

Investigating the impact of nicotine on executive functions using a novel virtual reality assessment.

AIMS: Nicotine is known to enhance aspects of cognitive functioning in abstinent smokers, but the effects on specific areas of executive functions and in non-smokers are inconclusive. This may be due in part to the poor sensitivity of tests used to assess executive functions. This study used a new virtual reality assessment of executive functions known as JEF (the Jansari assessment of Executive Functions) to address this issue. DESIGN: A 2 × 2 design manipulating group (smokers and never-smokers) and drug [nicotine (4 mg for smokers; 2 mg for never smokers) versus placebo gum]. SETTING: School of Psychology; University of East London. PARTICIPANTS: Seventy-two participants (aged 18-54 years): 36 minimally deprived (2 hours) smokers and 36 never-smokers. MEASUREMENTS: Components of executive function were measured using the virtual reality paradigm JEF, which assesses eight cognitive constructs simultaneously as well as providing an overall performance measure. FINDINGS: Univariate analyses of variance revealed that nicotine improved overall JEF performance, time-based prospective memory and event-based prospective memory in smokers (P < 0.01), but not in never-smokers. Action-based prospective memory was enhanced in both groups (P < 0.01) and never-smokers out-performed smokers on selective thinking and adaptive thinking (P < 0.01). CONCLUSIONS: Executive functioning and prospective memory as aspects of cognitive performance can be enhanced by nicotine gum in smokers who have abstained for as little as 2 hours.

Do suicidal thoughts or behaviors recur during a second antidepressant treatment trial?

OBJECTIVE: A subset of patients undergoing initial antidepressant treatment experience worsening of symptoms, including thoughts of suicide or suicidal behavior. The present study explores whether this subset of patients is also more likely to experience recurrence or worsening of these symptoms during a second treatment trial with a different antidepressant. METHOD: We examined data collected between July 2001 and September 2006 from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study, a multicenter effectiveness study of outpatients with major depressive disorder diagnosed by a DSM-IV checklist. In that study, subjects who did not remit with citalopram treatment were randomized among next-step treatment options. The main outcome measure for this post hoc analysis, presence of suicidal thoughts and behaviors, was assessed using the suicide item on the 16-item Quick Inventory of Depressive Symptomatology--Self-Rated. Logistic regression was used to examine association between emergence or worsening of these symptoms with the first-step (level 1) citalopram treatment and emergence or worsening with next-step (level 2) pharmacologic or psychosocial treatment, including augmentation with bupropion or buspirone; switch to sertraline, venlafaxine, or bupropion; or addition of or switch to cognitive therapy. RESULTS: Of 1,240 subjects entering level 2 with a score less than 3 on the suicide item, 102 (8.2%) experienced emergence or worsening of suicidal thoughts or behaviors. Emergence or worsening at level 1 was strongly associated with reemergence or worsening at level 2 (crude OR = 4.00 [95% CI, 2.45-6.51], adjusted OR = 2.95 [95% CI, 1.76-4.96]). Overall magnitude of risk was similar among next-step pharmacologic augmentation versus switching. CONCLUSIONS: These results suggest that individuals who experience emergence or worsening of suicidal thoughts or behaviors with one antidepressant treatment may warrant closer follow-up during the next-step treatment, as these symptoms may recur regardless of which modality is selected.

Expecting innovation: psychoactive drug primes and the generation of creative solutions.

Many individuals expect that alcohol and drug consumption will enhance creativity. The present studies tested whether substance related primes would influence creative performance for individuals who possessed creativity-related substance expectancies. Participants (n = 566) were briefly exposed to stimuli related to psychoactive substances (alcohol, for Study 1, Sample 1, and Study 2; and marijuana, for Study 1, Sample 2) or neutral stimuli. Participants in Study 1 then completed a creative problem-solving task, while participants in Study 2 completed a divergent thinking task or a task unrelated to creative problem solving. The results of Study 1 revealed that exposure to the experimental stimuli enhanced performance on the creative problem-solving task for those who expected the corresponding substance would trigger creative functioning. In a conceptual replication, Study 2 showed that participants exposed to alcohol cues performed better on a divergent thinking task if they expected alcohol to enhance creativity. It is important to note that this same interaction did not influence performance on measures unrelated to creative problem solving, suggesting that the activation of creativity-related expectancies influenced creative performance, specifically. These findings highlight the importance of assessing expectancies when examining pharmacological effects of alcohol and marijuana. Future directions and implications for substance-related interventions are discussed.

Mind-body interactions in pain: the neurophysiology of anxious and catastrophic pain-related thoughts.

The well-accepted biopsychosocial model proposes that the experience of pain and responses to it result from a complex interaction of biological, psychological, and social factors. However, the separation of these constructs is substantially artificial, and we presume that psychological processes have biological effects, that biological processes affect an individual's psychosocial environment, and so on. Considerable research has demonstrated that pain-coping strategies influence perceived pain intensity and physical functioning, and individual differences in styles of pain coping even shape the persistence of long-term pain complaints in some populations. A good deal of this coping research has focused on catastrophizing, which is a generally maladaptive cognitive and emotional mental set that involves feelings of helplessness when in pain, rumination about pain symptoms, and magnification of pain-related complaints. Collectively, catastrophizing has been consistently associated with heightened experiences of pain across a variety of samples. Although catastrophic thinking regarding pain-related symptoms is often classified under the "psychologic" category within the broader biopsychosocial model, we propose that catastrophizing exerts biologic effects that may account for some of its negative consequences. In general, the cognitive and affective processes captured within the construct of catastrophizing may exert effects on the neuromuscular, cardiovascular, immune, and neuroendocrine systems, and on the activity in the pain neuromatrix within the brain. The interface between pain-related neurobiology and processes such as pain-related catastrophizing represents an important avenue for future pain research.

Neuropsychological effects of formaldehyde use.

This study compared five individuals who intentionally ingested formaldehyde (possibly laced with PCP) in marijuana cigarettes to a control group on measures of cognitive ability. Formaldehyde, a major component in embalming fluid, is legal to purchase and possess and has become popular due to its euphoric properties. In significant doses, the chemical is a neurotoxin. The effects of inadvertent exposure are fairly well known, but the effects of intentional ingestion have only recently been investigated. In addition, there has been little research on the effects of formaldehyde use specific to intellectual ability and cognitive intactness. The results of this study indicate intentional ingestion may cause a decline in neuropsychological intactness, as measured by performance on the Shipley Institute of Living Scale.

Differences in depressive thoughts between major depressive disorder, IFN-alpha-induced depression, and depressive disorders among cancer patients.

OBJECTIVE: The objective of this study is to test the hypothesis that there are differences in the distribution of negative thoughts among major depressive disorders (MDD), depressive disorders among cancer patients, and IFN-alpha-induced depression. METHODS: Twenty-three patients affected by MDD, 25 cancer patients affected by depressive disorders (20 MDD), and 19 patients affected by IFN-alpha-induced depression satisfying MDD criteria were evaluated using the 17-item Hamilton Depression Rating Scale and the 13-item Beck Depression Inventory. RESULTS: Sense of guilt was higher among MDD patients (56.5%) and was lower among cancer patients (4%) (P<.0001). Sense of failure, dissatisfaction, and self-dislike were higher among MDD patients than among IFN-alpha patients (P<.0001). CONCLUSIONS: In our study, patients affected by MDD present a different pattern of symptoms in comparison with patients affected by IFN-alpha-induced depression and depressive disorders. In particular, core depressive thoughts were less frequent in the last two conditions.

Estrogen and comprehension of metaphoric speech in women suffering from schizophrenia: results of a double-blind, placebo-controlled trial.

OBJECTIVE: The effects of estrogen on comprehension of metaphoric speech, word fluency, and verbal ability were investigated in women suffering from schizophrenia. The issue of estrogen-dependent neuropsychological performance could be highly relevant because women with schizophrenia frequently suffer from hypoestrogenism. METHOD: A placebo-controlled, double-blind, crossover study using 17beta-estradiol for replacement therapy and as an adjunct to a naturalistic maintenance antipsychotic treatment was carried out over a period of 8 months. Nineteen women (mean age = 38.0 years, SD = 9.9 years) with schizophrenia were included in the study. Comprehension of metaphoric speech was measured by a lexical decision paradigm, word fluency, and verbal ability by a paper-and-pencil test. RESULTS: Significant improvement was seen for the activation of metaphoric meaning during estrogen treatment (P = .013); in contrast, no difference was found for the activation of concrete meaning under this condition. Verbal ability and word fluency did not improve under estrogen replacement therapy either. CONCLUSIONS: This is the very first study based on estrogen intervention instead of the physiological hormone changes to examine the estrogen effects on neuropsychological performance in women with schizophrenia. In addition, it is the first time that the effect of estrogen on metaphoric speech comprehension was investigated in this context. While in a previous study estrogen therapy as adjunct to a naturalistic maintenance treatment with antipsychotics did not show an effect on psychopathology measured by a rating scale, a significant effect of estrogen on the comprehension of metaphoric speech and/or concretism, a main feature of schizophrenic thought and language disturbance, was found in the present study. Because the improvement of formal thought disorders and language disturbances is crucial for social integration of patients with schizophrenia, the results may have implications for the treatment of these individuals.

Marijuana coping motives interact with marijuana use frequency to predict anxious arousal, panic related catastrophic thinking, and worry among current marijuana users.

The present investigation evaluated whether coping motives for marijuana use interacted with past 30-day frequency of marijuana use in relation to anxiety-relevant variables among community-recruited young adult marijuana users (n=149). As expected, after covarying cigarettes per day, alcohol use, and total years of marijuana use, the interaction between frequency of past 30-day marijuana use and coping motives predicted anxious arousal symptoms, agoraphobic cognitions, and worry. Marijuana users who demonstrated high use frequency and high coping motives demonstrated the highest levels of anxiety across these anxiety-relevant criterion variables. No such effects were evident, as expected, for depressive symptoms, offering explanatory specificity for anxiety relative to depressive factors. These results are discussed in relation to better understanding the role of marijuana use and coping motives in regard to anxiety vulnerability.

Treatment resistance in unipolar depression: Is it an iatrogenic phenomenon caused by antidepressant treatment of patients with a bipolar diathesis?

Major depressive disorder is a common psychiatric illness that is considered generally treatable; however, there are some patients who fail to respond in spite of adequate trials of antidepressants. Clinical factors known to contribute to treatment resistance include psychiatric and physical comorbidity, undiagnosed bipolarity, and treatment non-adherence. There is also emerging evidence that the use of antidepressants in some 'unipolar' patients may lead to a pattern of progressive diminution of therapeutic response and ultimately treatment resistance. A large number of these patients may have a bipolar diathesis even though there are no symptoms of hypomanic, manic or mixed episodes. It is hypothesized that the widespread and injudicious use of antidepressants in patients with a bipolar diathesis might result in treatment-induced resistant depression. Furthermore, attempts to manage the antidepressant-led mood instability might cause increased utilisation of other psychotropic drugs including sedative/hypnotics, neuroleptics and mood stabilisers and contribute to polypharmacotherapy.

Acute influences of estrogen and testosterone on divergent and convergent thinking in postmenopausal women.

Previous studies indicated an enhanced capability of divergent creative thinking in young women during the ovulatory phase, which expressed itself also by an increased dimensional complexity of ongoing electroencephalographic (EEG) activity. Considering the enhanced plasma levels of estrogen and testosterone characterizing the ovulatory phase, we tested whether short-term administration of estrogen or testosterone in postmenopausal women with constantly low levels of gonadal steroids induces similar changes in divergent thinking. In two placebo-controlled cross-over studies, healthy postmenopausal women (n=12, in each study, mean age 58 years, range 47-65 years) were treated transdermally over 3 days with estrogen and testosterone, respectively, at doses inducing plasma hormone concentrations comparable with those observed in young women around ovulation. Capabilities of divergent thought and convergent analytical thought, performance on motor perseveration, and verbal memory were examined. EEG activity was recorded while subjects performed on tasks of thinking and during mental relaxation. Estrogen impaired divergent thinking (p <0.01) and enhanced convergent thinking, motor perseveration, and memory for the initial word list (p <0.05 for all tests). In parallel, EEG dimensional complexity was reduced (p <0.05). Overall, these changes indicate an estrogen-induced shift from a "divergent" towards a more "convergent" mode of processing. However, overall less consistent, effects of testosterone were opposite to those of estrogen. It increased performance on some of the divergent thinking tasks (p <0.05), and tended to increase EEG dimensional complexity during divergent thinking. Data indicate a differential sensitivity of modes of thinking to short-term treatment with estrogen and testosterone in postmenopausal women.

Abstinence effects and reactivity to nicotine during 11 days of smoking deprivation.

The purpose of the present study was to investigate smoking abstinence effects and the dissipation of tolerance (reactivity to nicotine) under controlled laboratory conditions. Seventeen male and female regular smokers were tested first in a session following ad libitum smoking and then in an additional five sessions over the course of 11 days during which they abstained from smoking. A metered dose of nicotine was administered via intranasal spray to ensure standard exposure, and pre- and post-dosing measures of heart rate, blood pressure, cortisol, galvanic skin response (GSR), craving, and several DSM-IV withdrawal symptoms (anxiety, irritability, restlessness, difficulty concentrating, and appetite) were collected. Prior to the nicotine test dose during deprivation sessions, heart rate and systolic blood pressure evinced elements of both an 'offset abstinence pattern' (deflection in a direction opposite to that produced by smoking) and a 'transient abstinence pattern' (deflection followed by a subsequent return); for cortisol, an offset pattern was observed, whereas for GSR and craving, a transient pattern was found. With respect to loss of tolerance, heart rate reactivity was found to increase significantly after 2 days' abstinence from nicotine, and the increase was sustained in subsequent sessions. Cortisol reactivity revealed more gradual dissipation, with significant differences evident only after 9 days of abstinence. These findings extend research on nicotine abstinence effects and on the dissipation of tolerance to nicotine deprivation intervals of nearly 2 weeks and confirm prior observations of variability across different response systems.

The effects of 3-week estrogen hormone replacement on cognition in elderly healthy females.

RATIONALE: Estrogen concentrations decline with age and menopause is often followed by an acceleration of the age effects on cognition. It is suggested that replacement of estrogen would reinstate, at least in part, cognitive abilities. Effects of estrogens on memory have been reported in studies with women in a clinical setting who either needed or wished to have the estrogen replacement and are mostly in the perimenopausal age-band. OBJECTIVE: The present study investigated the effects of estradiol on memory and on frontal lobe function in elderly female subjects who did not suffer any of the postmenopausal symptoms and had never taken estrogen hormone replacement (EHR) previously. METHODS: EHR (Progynova TS, transdermal estradiol; n=19) or placebo (n=18) was given for a period of 3 weeks to elderly healthy female subjects. Memory, frontal lobe functions (inhibition and planning) and visuospatial abilities (mental rotation) were tested before and after treatment. Estrogen plasma levels were measured to confirm the result of EHR. Cortisol plasma levels were also measured before and after cognitive performance in order to evaluate the effects of EHR on the sensitivity of the hypothalamo-pituitary-adrenal (HPA) axis to mild mental stress. RESULTS: Plasma estradiol levels in the drug group increased to levels equivalent to that of a fertile woman (0.21+/-0.5 nmol/l). Memory function as well as visuospatial abilities as measured by a mental rotation task improved significantly with EHR. However, there was no effect of EHR on frontal lobe functions. The cognitive effects were not dependent on an improvement in mood or general well-being as may be the case with EHR in women at peri- or post-menopausal stage. EHR was found to increase the HPA response to task-induced stress, as indicated by an increase in cortisol plasma levels. CONCLUSIONS: The present study has provided evidence of a beneficial effect of EHR on cognitive abilities given for first time to healthy elderly women. Furthermore, the present study has demonstrated a differential effect of EHR on memory, visuospatial abilities and frontal lobe function.

Event-related potential measures of information processing during general anesthesia.

To investigate the incidence and manner of auditory information processing during a state of presumed unconsciousness event-related brain potentials (ERPs) were studied in 41 patients undergoing cardiac surgery with propofol/alfentanil anesthesia. The ERPs were recorded during auditory oddball tasks administered before and within several periods of the operation. Mean nasopharyngeal temperature and anesthetic concentrations were determined for each intraoperative ERP recording epoch. During anesthesia ERP waves could still be observed up to 500 ms after stimulus onset indicating that auditory information processing was not suppressed completely by the administered anesthetic agents. Relative to the preoperative recordings, the P1-N1-P2 complex was delayed and more positive going during anesthesia. Comparable changes in ERP morphology have been observed during Stage II-IV sleep, suggesting parallels in the mechanisms underlying early auditory processing in both states of reduced arousal level, possibly related to a selective reduction of a non-specific activity. N1 and P2 peak amplitudes were found to be larger for the deviant tones compared to the standard tones. These amplitude differences most likely reflect automatic detection of stimulus deviance, although it cannot be excluded entirely that they were due to differences in refractoriness. Anesthetic concentrations and nasopharyngeal temperature were found to be of minor significance for ERP control. It is suggested that ERPs could serve as intraoperative reference measures, providing the earliest evidence for auditory processing. This characteristic is important for validation of signals and techniques that are proposed to improve conventional monitoring of anesthesia with respect to detecting unintended awareness.

Effects of early adolescent drug use on cognitive efficacy in early-late adolescence: a developmental structural model.

Despite an accumulated body of research evidence that documents the negative physical consequences of chronic alcohol and drug use, it is less clear whether the use of these same substances produces impaired cognitive abilities during the early stages of use. Early drug use may impede acquisition of critical thinking skills and hinder the learning of important cognitive strategies required for successful transition to adulthood. To better understand these relations, longitudinal latent-variable analyses were used to examine the effects of early adolescent drug use on early-late adolescent cognitive efficacy. Latent factors of polydrug use, behavioral control, and cognitive efficacy were hypothesized in early adolescence, the latter two controlling for potential spurious relations. At outcome, six constructs were hypothesized tapping polydrug use, cognitive mastery, self-reinforcement, problem-solving confidence, decision-making skills, and cognitive and affective self-management strategies. Models were psychometrically sound and accounted for large portions of variance. Early adolescent drug use had a small but significant negative effect on cognitive and affective self-management strategies. By the 12th grade, linkages between drug use and cognitive functioning were of larger magnitude than long-term influences, perhaps reinforcing the argument that deficits in cognitive skills are developmentally delayed and surface only with exacerbated or persistent drug use. Overall, specific effects of drug use adversely influenced important cognitive skills that may be critically related to functioning in both interpersonal and intrapersonal domains.

The effects of nicotine upon memory and problem solving performance.

This study examined the effects of 4 mg nicotine and placebo upon problem solving performance in word and number tasks, and subsequent recall and recognition of the answers to these problems. The results demonstrated that the drug had no effect upon the subject's ability to generate the correct answers to the problems, but that immediate and delayed recall and recognition were significantly impaired. These data clearly do not support the view that nicotine, without exception, enhances information processing, and it was suggested that the effects of nicotine upon information retrieval may be specific to tasks which assess episodic memory in the absence of retrieval cues or a problem solving context.

The separate and combined effects of scopolamine and nicotine on human information processing.

Previous work in this and another laboratory has shown that nicotine tablets improve the performance of a rapid information processing task and reduce the Stroop effect, whereas scopolamine has the opposite effects. The purpose of this study was to extend these previous findings by determining whether, when administered together, these two drugs have mutually antagonistic effects on task performance. Two experiments are reported, both using within-subjects double-blind Latin Square designs. In the first, six subjects received single and combined doses of scopolamine 1.2 mg and nicotine 1.5 mg, and there was some evidence that the two drugs had mutually antagonistic effects on the rapid information processing task. In the second experiment 12 subjects received the same doses, but rapid information processing testing was carried out over a longer time period and Stroop testing was introduced at the end of the 2.5 h session. Nicotine was found to counteract the depression of performance produced by scopolamine on both the rapid information task and the Stroop test. These results provide further support for the theory that central cholinergic pathways play a major role in human information processing.