Nicotine withdrawal and reward responsivity in a card-sorting task

Rationale  Animal studies have demonstrated decreased reward responsivity during nicotine withdrawal (e.g., Epping-Jordan et al., Nature 393:76–79, 1998) and the Card Arranging Reward Responsivity Objective Test (CARROT) has recently been used to study the effect of nicotine withdrawal on reward responsivity in humans (e.g., Al-Adawi and Powell, Addiction 92:1773–1782, 1997; Powell et al., Biol Psychiatry 51:151–163, 2002). We investigated a suggestion that nicotine withdrawal may have additional reward-related effects apart from the reward responsivity effects already observed. Objective  The objective of this study was to determine whether or not nicotine withdrawal results in slower improvements in performance on a card-sorting task over a series of trials. Method  We carried out two experiments using a modified version of the CARROT, the mCARROT, to compare the performance of human participants in nicotine withdrawal with those who were satiated. Results  Although withdrawal produced no direct effect on the mCARROT measure of reward responsivity, the overall sorting rate was lower, and the increase in sorting rate across successive trials was slower during nicotine withdrawal than during satiation. Conclusions  These data indicate that nicotine withdrawal impacted on task performance independently of the introduction of a performance contingent reward, suggesting a novel reward-related effect of nicotine withdrawal.     

Memory associations between negative emotions and alcohol on the lexical decision task predict alcohol use in women

Implicit alcohol expectancies, or beliefs about alcohol which exist in the form of automatic memory associations, are thought to uniquely affect drinking behavior. Research also has indicated that there may be a distinctive relationship between negative reinforcement and alcohol use in women. However, the most common measures used to examine implicit alcohol cognitions may be insufficient to examine associations involving negative reinforcement. The current study utilized the Lexical Decision Task (LDT) to examine the relationship between implicit alcohol cognitions and reported drinking in a sample of college women. Seventy-eight female participants completed a LDT including alcohol- and emotion-words, questionnaire measures of explicit alcohol expectancies, and a measure of drinking behavior at baseline and after two months. Strong associations between negative emotion-words and alcohol-words (as measured by the LDT) were found to predict drinking at follow up, and to account for unique variance in drinking beyond the contribution of explicit measures. In addition, women who reported heavier drinking in response to social conflict on an explicit measure showed stronger priming of alcohol words by negative emotion words, thus implying that the LDT may tap into implicit cognitions related to alcohol use as a method of coping. These findings suggest that the LDT is sensitive to negative-reinforcement associations in a way that other measures are not.     

Nicotine and smoking: Effects upon subjective changes in mood

A Mood Adjective Check List and an activation scale were used to measure subjective reports on mood changes in 24 male habitual smokers before and after smoking cigarettes with known content of nicotine, at different times of day and rates of puffing. Ratings on pleasantness were dose related. Aggression and anxiety showed effects attributable to circadian influence and slight decreases in both factors occurred after smoking the highest nicotine cigarette. The MACL scores were greatly affected by the experimental procedure. Levels of inner tension were found related to the nicotine inhaled. The heuristic value of the concept of activation in these studies is suggested.This work was supported by the Tobacco Research Council, and carried out at the Institute of Psychiatry, London.     

Nicotine administration in rabbits using Habitrol nicotine patches and nicotine nasal spray

1. Several methods are used to provide predictable and effective nicotine to experimental animals in scientific studies. Due to the expense and technical challenges of these methods, we sought suitable alternatives. Consequently, the purpose of the present study was to develop a reliable experimental nicotine protocol in rabbits that included either Habitrol nicotine patches (Novartis Consumer Health Inc., Summit, NJ, USA) or nicotine nasal spray. 2. Administration of one of three doses of nicotine (2.5, 5, or 10 mg) was accomplished daily on 13 rabbits divided between either the patch or spray groups. Systemic nicotine and cotinine levels at 0 h, 15 min and 8 and 24 h were assayed. Data were analysed by a Fisher's protected least significant difference test at P = 0.05. 3. Rabbits treated with Habitrol patches exhibited consistent and predictable systemic nicotine levels. The nicotine nasal spray produced an immediate dose-dependent response with no measurable nicotine serum levels at 8 h. 4. For nicotine administration in rabbits, nicotine patches are easy to administer and provide a nicotine serum level between 5 and 25 ng/mL, which is consistent with the average daily level found in a patient who smokes cigarettes.     

Smoking,processing speed and attention in a choice reaction time task

Nineteen subjects performed a choice reaction time task in which two levels of choice (two and four stimuli), and two levels of spatial attention (narrow and wide) were manipulated under each of two smoking conditions: sham smoking (denicotinised cigarette) or regular smoking (0.8 mg nicotine cigarette). All three factors significantly affected reaction time, with the smallest reaction times being recorded to the two-choice narrow grouped stimuli recorded under the high nicotine condition. Nicotine appears to speed decision time for both complex and hard-to-attend tasks, which is compatible with a role for nicotinic receptors in systems jointly mediating attention, memory and processing speed.     

Nicotine improves performance in an attentional set shifting task in rats

A large number of studies in both humans and experimental animals have demonstrated nicotine-induced improvements in various aspects of cognitive function, including attention and memory. The prefrontal cortex (PFC) is thought to be critically involved in the modulation of executive function and these attentional processes are enhanced by nicotine acting at nicotinic acetylcholine receptors. The involvement of nicotinic processes on cognitive flexibility in particular has not been specifically investigated. The effects of nicotine on attentional flexibility were therefore evaluated using the rodent attentional set shifting task in rats. Nicotine injected both acutely and following repeated pre-exposure significantly improved both intradimensional and extradimensional set shifting performance in the task. Further investigation of the acute effects of nicotine demonstrated this improvement in attentional flexibility to be dose-dependent. These results implicate the nicotinic receptor system in the mediation of processes underlying cognitive flexibility and suggest that nicotine improves attentional flexibility in rats, both within and between perceptual dimensions of a compound stimulus. Nicotine-induced alterations in prefrontal circuitry may underlie these effects on cognitive flexibility. This article is part of a Special Issue entitled 'Cognitive Enhancers'.     

Nicotine improves memory in an object recognition task in rats.

Nicotine was investigated for its mnemonic effect in a two trials object recognition task. In the first trial, two copies of the same object were presented. In the second trial (24 h after), one of the familiar object and a new object were presented. The time spent exploring the new object by control rats was not significantly different from the exploration time of the familiar object, indicating that they did not remember the familiar object. Rats injected with nicotine before the first trial, after the first trial or before the second trial spent more time in exploring the new object than the familiar one at the second trial. These results suggest that, in normal rats, acute nicotine enhances acquisition, consolidation and restitution of the information in an object recognition task.     

Yoga training and motor speed based on a finger tapping task

A finger tapping task was used to assess motor speed (MS) of both hands in 53 adults and 152 children before and after yoga training and in 38 adults of a non-yoga (control) group. All subjects were right hand dominant. The 30-second tapping speed (TS) test was considered as three time intervals, i.e. 0-10 second (TS1), 10-20 seconds (TS2) and 20-30 seconds (TS3). There was a significant (Student's t-test) increase in all three TS values following 10 days of yoga in children and 30 days of yoga in adults. However for both groups at baseline and final assessments, TS2 and TS3 were significantly lower than TS1. Hence the TS was increased after yoga training during the first 10-seconds of the test but not during the next 20 seconds. These results suggest an increase in motor speed for repetitive finger movements following yoga training, but not in strength or endurance, as the increase was not sustained over 30 sec.     

Nicotine enhances sustained attention in the rat under specific task conditions

Although nicotine has cognitive enhancing effects in both animals and humans, most studies in humans have only shown consistent improvements in sustained attention. Moreover, many studies with smokers have been criticised, since nicotine may simply be relieving withdrawal-induced deficits. The present study investigated the effect of nicotine on sustained attention in drug-naïve rats using a five-choice serial reaction time task. Initially, the task was demonstrated to satisfy some of the criteria for the construct validity of a vigilance task: reducing signal length and either increasing or decreasing the inter-trial interval significantly (P<0.05) impaired performance. Whether nicotine (0.05–0.4 mg/kg, SC) reversed the deficits induced by a signal length of 0.25 s (weak signal) or an inter-trial-interval of either 20 s (low event rate) or 1 s (high event rate) was assessed. Nicotine (0.15 mg/kg) improved accuracy and decreased omission errors under low event rate conditions only. However, nicotine (0.05/0.15 mg/kg) improved reaction time and increased anticipatory responses under both weak signal and low event rate conditions. There was no effect of nicotine on performance under high event rate conditions. Under the low event rate condition, nicotine enhanced the ability of rats to maintain attention (i.e. accuracy) throughout a session. These findings suggest (i) that nicotine’s effect on attention depends upon task characteristics; (ii) these effects on attention may reflect self-reports by smokers that nicotine aids concentration, particularly in stressful situations, and (iii) nicotinic agonists may have therapeutic benefits in patient populations suffering from attentional deficits.     

Captopril and enalapril improve cognition and depressed mood in hypertensive patients

In this study, we evaluate the effects of two angiotensin converting enzyme inhibitors (ACEIs), captopril and enalapril given chronically as antihypertensive treatment, on certain cognitive and emotional processes in humans. Thirty-nine subjects with mild to moderate hypertension and fifteen normotensive controls were divided into four groups consisting of normotensive and hypertensive subjects taking captopril, enalapril, or no medication at all. The Rey Auditory Verbal Learning Test and the Wechsler Memory Scale were used to evaluate their cognitive functioning. Mood changes in all subjects were assessed using the Beck Depression Inventory and the Hopkins Symptom Check- list (HSC). Results: Untreated hypertensive patients scored lower than normotensive controls in cognitive tests and significantly worse in cumulative recall (P < 0.05) and paired words association (P < 0.01). When compared with normotensive subjects, untreated hypertensive patients also scored significantly higher on the depression with anxiety subscale in HSC (P < 0.05). No significant influence of hypertension was found in any other examined aspect of cognition and mood. In most cases captopril improved and enalapril reversed the adverse memory effects of hypertension. High arterial blood pressure is significantly associated with an impairment of cognition and the occurrence of depression with anxiety in humans. Enalapril and, to a lesser extent, captopril reversed these deficits.     

Nicotine effects on affective response in depression-prone smokers

Rationale Comorbidity between cigarette smoking and depression is thought to arise because depression-prone smokers self-administer nicotine to improve mood. Yet little evidence supports this view, and nicotine’s effect on positive affect deficiency in depression remains largely unstudied. Objectives We hypothesized that (1) nicotine would dispel negative affect and enhance positive affect and (2) effects would be stronger for smokers vulnerable to depression, particularly during a depressed state. Materials and methods Regular smokers (N = 165) were recruited from the community: 63 with no history of major depressive disorder (MDD), 61 with recurrent past but no current MDD, and 41 with both current and past MDD. During four sessions, participants smoked either a nicotinized (NIC+) or denicotinized (NIC−) cigarette double blind after experiencing a negative mood induction or while undergoing a positive mood induction. Positive and negative affects were measured at baseline and at two time points after smoking. Results Previously depressed smokers showed a heightened positive mood response to positive mood induction when smoking a nicotinized cigarette. Nicotine also increased the degree to which positive mood induction dispelled negative mood in depression-vulnerable smokers. Finally, nicotine worsened the negative affect response to negative mood induction for all groups. Conclusion Self-administering nicotine appears to improve depression-prone smokers’ emotional response to a pleasant stimulus.     

Attention control in mood and anxiety disorders: evidence from the antisaccade task

The antisaccade task (in which participants must suppress a reflexive saccade towards a sudden, peripheral stimulus and generate a volitional saccade in the opposite direction) is considered a measure of cognitive inhibition. The task has been used to examine cognitive control deficits in several neuropsychiatric conditions, most notably schizophrenia. This commentary summarizes recent evidence from antisaccade tasks in mood and anxiety disorders, with reference to neuropsychological models and psychopharmacological mechanisms. Copyright © 2013 John Wiley & Sons, Ltd.     

Nicotine improves Morris water task performance in rats given medial frontal cortex lesions

The object of this study was to investigate whether nicotine would improve cognitive impairments produced by medial frontal cortex lesions in rats behaviorally tested on the Morris water task (MWT). Rats were assigned to either a lesion or sham group. In the lesion group, animals were given vehicle (peanut oil) treatment or treatment with nicotine for 11 consecutive days before, after, or before and after a medial frontal cortex lesion. Additionally, a sham group was included that was given vehicle both before and after the lesion. Results showed that lesioned rats receiving pre- or post-operative nicotine treatment demonstrated improved Morris task acquisition performance relative to the lesioned group given the vehicle, although a deficit was shown relative to shams. On the probe trial, rats that received a pre- and post-treatment of nicotine demonstrated performance equivalent to shams and had significantly better performance than rats that received nicotine treatment before the lesion and lesioned animals treated with the vehicle. These results demonstrate that nicotine has therapeutic effects in rats that have received cortical injury.     

Negative mood induction normalizes decision making in male cocaine dependent individuals

Rationale  

Decision making is thought to play a key role in psychostimulant relapse, but very few studies have addressed the issue of how to counteract decision-making deficits in addicted individuals. According to the somatic marker framework, pervasive decision-making problems in addicted individuals may relate to abnormalities in the processing of emotional signals that work to anticipate the prospective outcomes of potential decisions.     

Simultaneous blockade of dopamine and noradrenaline reuptake promotes disadvantageous decision making in a rat gambling task

Rationale

The inability to make profitable long-term decisions has been implicated in several psychiatric disorders. There is emerging evidence to support a role for dopamine (DA) in decision making, but our understanding of the role of noradrenaline (NA) and serotonin (5-HT) in decision making, and of possible interactions between the three monoamines, is limited. Moreover, impulsivity has been associated with aberrant decision making, but the underlying mechanisms are incompletely understood.

Objective

The purpose of this study is to improve our understanding of the neuropharmacological mechanisms of decision making and impulse control.

Methods

We investigated the effects of amphetamine (0.25–1.0 mg/kg) and selective reuptake inhibitors of DA (GBR12909; 2.5–10 mg/kg), NA (atomoxetine; 0.3–3.0 mg/kg), and 5-HT (citalopram; 0.3–3.0 mg/kg) in a rat gambling task (rGT). Since the rGT allows for detection of impulsive action, i.e., premature responding, we also assessed the relationship between decision making and impulsivity.

Results

In the rGT, rats developed an optimal choice strategy from the first session onwards. Elevation of endogenous DA or NA levels increased and decreased impulsivity, respectively, but did not alter decision making. However, simultaneous blockade of DA and NA disrupted decision making, reflected by a relative decrease in choice for the advantageous choice options. Increasing 5-HT neurotransmission did not affect decision making or impulsivity.

Conclusions

These data suggest important but complementary or redundant roles of DA and NA neurotransmission in decision-making processes based on reward probability and punishment. Moreover, impulse control and decision making in the rGT rely on dissociable mechanisms.     

Nicotine poisoning in a dog

Nicotine poisoning is a rarely reported toxicosis. The clinical signs and symptoms are complex and are mostly of central nervous system derangement. In addition, animals may have hypersalivation, vomiting, diarrhea, tachycardia, tachypnea, hypertension and hyperthermia. Some animals are presented in total collapse with slow and shallow respirations, hypotension, dilated pupils, and a weak, rapid and irregular pulse. Treatment is directed toward removing the unabsorbed poison and diluting, and counteracting or controlling the animal's signs. This report emphasises the comparative ease with which a dog would readily ingest chewing tobacco, which is sweet in taste, and come down with nicotine poisoning, as compared to cigarette tobacco which is nonpalatable and therefore less of a threat. The report further discusses clinical nicotine toxicosis, its incidence, clinical manifestations, diagnosis, prognosis and treatment.     

Nicotine dependence,internalizing symptoms,mood variability and daily tobacco use among young adult smokers

IntroductionCigarette use among young adults continues to rise. As young adults transition to college and assume other adult roles and responsibilities, they are at risk for the development of mental health problems and for the progression of substance use problems. Previous studies suggest that individual differences in negative and positive mood contribute to cigarette use in established college-aged smokers, but less is known whether fluctuations in mood influence daily cigarette use, controlling for trait levels of internalizing symptoms and nicotine dependence.MethodsData for this study came from a sample of college students (N = 39, 59% female, mean age 20.4 years) who reported regular cigarette use and participated in a 21-day ecological momentary assessment (EMA) study assessing within-individual variation in cigarette use and mood.ResultsA three-level hierarchical linear model accounting for the structure of 1896 occasions of cigarette use nested within days and individuals indicated that within-individual variability in positive mood was associated with cigarette use at each occasion, after taking into account baseline levels of nicotine dependence and internalizing problems.ConclusionsDaily shifts in positive moods are importantly associated with consuming cigarettes throughout the day.     

Stressor-provoked response patterns in a swim task: modification by diazepam

When placed in a water-filled arena in which one area is illuminated mice tend to remain in the illuminated region. Moreover, in a forced-swim task mice initially exhibit vigorous responding followed by a rapid decay of active swimming, and the adoption of a characteristic floating posture. Immediately following exposure to inescapable shock the response invigoration was appreciably enhanced, as was the tendency to remain in the illuminated region of the arena. Administration of low doses of diazepam (0.5 and 1.0 mg/kg) prior to testing effectively eliminated the response invigoration, as well as the response of approaching the illuminated region of the arena. It is proposed that the behavioral variations evident soon after uncontrollable shock are related to a transient increase of anxiety or vigilance. Moreover, it is suggested that several time-dependent behavioral variations associated with inescapable shock may be related to alterations of anxiety.     

Nicotine and caffeine effects on the task-elicited blood pressure response

Nine subjects participated in four daily sessions during which a psychomotor task was performed prior to and following drug administration. Blood pressure was reliably increased by task performance, cigarette smoking, and caffeine administration. The effect of the combination of task performance, cigarette smoking and caffeine administration was additive, resulting in a markedly increased blood pressure during task performance for subjects smoking cigarettes and receiving caffeine.