Hormonal contraceptive use predicts decreased perseverance and therefore performance on some simple and challenging cognitive tasks

A growing body of research suggests that hormonal contraceptive (HC) use may be associated with lower self-control, as well as structural and functional differences in women's brains that could contribute to differences in perseverance on tasks requiring cognitive control. Here, we sought to extend this research by examining the relationship between HC use and college-aged women's perseverance (i.e., time spent) and performance on tasks requiring cognitive control. Across two studies, we find that, compared to naturally-cycling women, women using HCs display less perseverance on both simple (i.e., a spot-the-difference game) and challenging (i.e., Graduate Record Examination quantitative problems) tasks. Moreover, these differences in perseverance were found to predict performance decrements across tasks, with women taking HCs performing worse because they spent less time on the tasks. By demonstrating how HC use may influence perseverance and thereby performance, these results contribute to a growing body of research examining the unintended implications of HC use on cognition, learning, and memory.

Effects of aripiprazole versus risperidone on brain activation during planning and social-emotional evaluation in schizophrenia: A single-blind randomized exploratory study

Impaired function of prefrontal brain networks may be the source of both negative symptoms and neurocognitive problems in psychotic disorders. Whereas most antipsychotics may decrease prefrontal activation, the partial dopamine D2-receptor agonist aripiprazole is hypothesized to improve prefrontal function. This study investigated whether patients with a psychotic disorder would show stronger activation of prefrontal areas and associated regions after treatment with aripiprazole compared to risperidone treatment. In this exploratory pharmacological neuroimaging study, 24 patients were randomly assigned to either aripiprazole or risperidone. At baseline and after nine weeks treatment they underwent an interview and MRI session. Here we report on brain activation (measured with arterial spin labeling) during performance of two tasks, the Tower of London and the Wall of Faces. Aripiprazole treatment decreased activation of the middle frontal, superior frontal and occipital gyrus (ToL) and medial temporal and inferior frontal gyrus, putamen and cuneus (WoF), while activation increased after risperidone. Activation increased in the ventral anterior cingulate and posterior insula (ToL), and superior frontal, superior temporal and precentral gyrus (WoF) after aripiprazole treatment and decreased after risperidone. Both treatment groups had increased ventral insula activation (ToL) and middle temporal gyrus (WoF), and decreased occipital cortex, precuneus and caudate head activation (ToL) activation. In conclusion, patients treated with aripiprazole may need less frontal resources for planning performance and may show increased frontotemporal and frontostriatal reactivity to emotional stimuli. More research is needed to corroborate and extend these preliminary findings.

Vitamin B12 and Folic Acid Improve Gross Motor and Problem-Solving Skills in Young North Indian Children: A Randomized Placebo-Controlled Trial

Objectives

Deficiencies of vitamin B12 and folate are associated with delayed development and neurological manifestations. The objective of this study was to measure the effect of daily supplementation of vitamin B12 and/or folic acid on development in young North Indian children.

Methods

In a randomized, double blind trial, children aged six to 30 months, received supplement with placebo or vitamin B12 and/or folic acid for six months. Children were allocated in a 1:1:1:1 ratio in a factorial design and in blocks of 16. We measured development in 422 children by the Ages and Stages Questionnaire 3rd ed. at the end of the intervention.

Results

Compared to placebo, children who received both vitamin B12 and folic acid had 0.45 (95% CI 0.19, 0.73) and 0.28 (95% CI 0.02, 0.54) higher SD-units in the domains of gross motor and problem solving functioning, respectively. The effect was highest in susceptible subgroups consisting of stunted children, those with high plasma homocysteine (> 10 μmol/L) or in those who were younger than 24 at end study. With the exception of a significant improvement on gross motor scores by vitamin B12 alone, supplementation of either vitamin alone had no effect on any of the outcomes.

Conclusion

Our findings suggest that supplementation of vitamin B12 and folic acid benefit development in North Indian Children.

Trial Registration

ClinicalTrials.gov NCT00717730

Assessment of the effects of sex and sex hormones on spatial cognition in adult rats using the Barnes maze

Although sex differences and hormone effects on spatial cognition are observed in humans and animals, consensus has not been reached regarding exact impact on spatial working or reference memory. Recent studies in rats suggest that stress and/or reward, which are often different in tasks used to assess spatial cognition, can contribute to the inconsistencies in the literature. To minimize the impact of these sex- and sex hormone-sensitive factors, we used the Barnes maze to compare spatial working memory, spatial reference memory and spatial learning strategy in adult male, female, gonadectomized (GDX) male, and GDX male rats supplemented with 17β-estradiol (E) or testosterone propionate (TP). Rats received four acquisition trials, four trials 24h later, and a single retention trial one week after. Males and females acquired the task during the first four trials and retained the task thereafter. In contrast, GDX rats took longer to acquire the task and showed retention deficits at 1week. All deficits were attenuated similarly by TP and E. Assessment of search patterns also showed that strategies in the males transitioned from random to spatially focused and eventually direct approaches to the goal. However, this transition was faster in control and GDX-TP than in GDX and GDX-E rats. In contrast, the females almost invariantly followed the maze edge in thigmotactic, serial searches. Thus, while Barnes maze reveals activational, in part estrogenic effects on spatial cognition in males, its amenability to animals' use of multiple strategies may limit its ability to resolve mnemonic differences across sex.

Long-term effects of LCPUFA supplementation on childhood cognitive outcomes

BACKGROUND

The effect of long-chain polyunsaturated fatty acid (LCPUFA) intake on cognitive development is controversial. Most randomized trials have assessed cognition at 18 mo, although significant development of cognitive abilities (early executive function) emerge later.

OBJECTIVE

The objective was to evaluate cognition beyond 18 mo and longitudinal cognitive change from 18 mo to 6 y in children who were fed variable amounts of docosahexaenoic acid (0.32%, 0.64%, and 0.96% of total fatty acids) and arachidonic acid (ARA; 0.64%) compared with children who were not fed LCPUFA as infants.

DESIGN

Eighty-one children (19 placebo, 62 LCPUFA) who participated in a double-blind, randomized trial of LCPUFA supplementation as infants were re-enrolled at 18 mo and tested every 6 mo until 6 y on age-appropriate standardized and specific cognitive tests.

RESULTS

LCPUFA supplementation did not influence performance on standardized tests of language and performance at 18 mo; however, significant positive effects were observed from 3 to 5 y on rule-learning and inhibition tasks, the Peabody Picture Vocabulary Test at 5 y, and the Weschler Primary Preschool Scales of Intelligence at 6 y. Effects of LCPUFAs were not found on tasks of spatial memory, simple inhibition, or advanced problem solving.

CONCLUSIONS

The data from this relatively small trial suggest that, although the effects of LCPUFAs may not always be evident on standardized developmental tasks at 18 mo, significant effects may emerge later on more specific or fine-grained tasks. The results imply that studies of nutrition and cognitive development should be powered to continue through early childhood. This parent trial was registered at clinicaltrials.gov as NCT00266825.

Recovery in schizophrenia: focus on neurocognitive functioning

Recovery encompasses symptom remission and functional elements such as cognition, social functioning and quality of life. Personal recovery is also important in illness management to help the person stay on track with treatment and focus on activities unrelated to taking medication that maintain mental health. In the present study we aimed to identify neurocognitive functioning in two clinically stable groups of patients with personal recovery and non-recovered patients. The results showered generalized cognitive deficits in both groups while the non-recovery group was more impaired in verbal and visual memory, acoustic and tactile gnosis and neurodynamics and executing functioning. Interestingly the recovery group demonstrated lack of programming of actions and sufficient error monitoring and self-correction whereas the non-recovery group was significantly more impaired in all executive domains. The obtained results could be beneficial in identifying a target for psychosocial treatments and specifically cognitive remediation for patients with schizophrenia to facilitate the process of recovery.

Effects of modafinil on non-verbal cognition, task enjoyment and creative thinking in healthy volunteers

Background

Modafinil, a putative cognitive enhancing drug, has previously been shown to improve performance of healthy volunteers as well as patients with attention deficit disorder and schizophrenia, mainly in tests of executive functions. The aim of this study was to investigate the effects of modafinil on non-verbal cognitive functions in healthy volunteers, with a particular focus on variations of cognitive load, measures of motivational factors and the effects on creative problem-solving.

Methods

A double-blind placebo-controlled parallel design study evaluated the effect of 200 mg of modafinil (N = 32) or placebo (N = 32) in non-sleep deprived healthy volunteers. Non-verbal tests of divergent and convergent thinking were used to measure creativity. A new measure of task motivation was used, together with more levels of difficulty on neuropsychological tests from the CANTAB battery.

Results

Improvements under modafinil were seen on spatial working memory, planning and decision making at the most difficult levels, as well as visual pattern recognition memory following delay. Subjective ratings of enjoyment of task performance were significantly greater under modafinil compared with placebo, but mood ratings overall were not affected. The effects of modafinil on creativity were inconsistent and did not reach statistical significance.

Conclusions

Modafinil reliably enhanced task enjoyment and performance on several cognitive tests of planning and working memory, but did not improve paired associates learning. The findings confirm that modafinil can enhance aspects of highly demanding cognitive performance in non-sleep deprived individuals.

This article is part of a Special Issue entitled ‘Cognitive Enhancers’.

[Intellectual abilities in adolescents with former ADHD diagnoses - relationships to current ADHD symptoms, comorbid symptoms, and medication history: results of an 8.5-year follow-up of the Cologne Adaptive Multimodal Treatment Study (CAMT)]

OBJECTIVE

The current analysis was conducted on 16- to 22-year-old persons who had received a multimodal treatment for ADHD during their childhood. The main objective was to analyse the relationships between current intellectual abilities and current ADHD symptoms, comorbid symptoms, and medication history.

METHOD

In an 8.5-year follow-up study current intellectual ability was assessed with the German version of the KAIT (K-TIM). Behavioural problems were rated by parents and the former patients via standardized questionnaires and a semistructured interview. T-tests, Pearson correlations, and multiple regression analyses were then conducted.

RESULTS

No significant correlations were found between former treatment with medication and current intellectual abilities. Moreover, no relationship was found between intellectual abilities and current ADHD symptoms as assessed by self- and parent-rating via questionnaires. However, adolescents with lower IQ did show higher scores of problematic performance behavior during the test. Also, a correlation was found between overall clinical judgement and externalizing problem behavior at home and in school.

CONCLUSIONS

Only small correlations were found between the current residual symptoms and intelligence in adolescent and young adults who had received a diagnosis of ADHD in childhood.

Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks

γ-Aminobutyric acid (GABA) is a kind of amino acid contained in green tea leaves and other foods. Several reports have shown that GABA might affect brain protein synthesis, improve many brain functions such as memory and study capability, lower the blood pressure of spontaneously hypertensive rats, and may also have a relaxation effect in humans. However, the evidence for its mood-improving function is still not sufficient. In this study, we investigated how the oral intake of GABA influences human adults psychologically and physiologically under a condition of mental stress. Sixty-three adults (28 males, 35 females) participated in a randomized, single blind, placebo-controlled, crossover-designed study over two experiment days. Capsules containing 100 mg of GABA or dextrin as a placebo were used as test samples. The results showed that EEG activities including alpha band and beta band brain waves decreased depending on the mental stress task loads, and the condition of 30 min after GABA intake diminished this decrease compared with the placebo condition. That is to say, GABA might have alleviated the stress induced by the mental tasks. This effect also corresponded with the results of the POMS scores.

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.

The effect of alcohol, THC and their combination on perceived effects, willingness to drive and performance of driving and non-driving tasks

BACKGROUND

Driving under the influence of drugs (DUID) is one of the main causes of car accidents. Alcohol and marijuana are the most popular drugs among recreational users. Many classify these drugs as "Light" drugs and therefore allow themselves to drive after consuming them.

OBJECTIVE

The study had two main objectives: 1) to investigate the effect of alcohol (BAC=0.05%), THC (13 mg) and their combination on driving and non-driving tasks. 2) to investigate the extent to which people are willing to drive based on their subjective sensations and their perceived effects of the drugs.

METHOD

7 healthy men and 5 healthy women, ages 24-29, all recreational users of alcohol and marijuana, completed 5 experimental sessions. Sessions included: drinking and smoking placebo, drinking alcohol and smoking placebo, drinking placebo and smoking THC, drinking alcohol and smoking THC, drinking placebo and smoking placebo 24 hours after drinking alcohol and smoking THC. Three types of measures were used: subjective perceptions (with questionnaires), performance parameters of the driving and non-driving tasks (arithmetic task and a secondary target detection task) and physiological changes (heart rate).

RESULTS

Overall, the combination of alcohol and THC had the most intense effect after intake. This effect was reflected in performance impairments observed in the driving and non-driving tasks, in the subjective sensations after intake, and in the physiological measures. Despite significant differences in the size of the effects after the various treatments, there were no differences in the distances subjects were willing to drive while under the influence on each of the treatments.

Prospective cognitive follow-up in primary CNS lymphoma patients treated with chemotherapy and reduced-dose radiotherapy

High-dose chemotherapy and whole brain radiotherapy (WBRT) can prolong survival in primary CNS lymphoma (PCNSL) patients, but is often associated with clinically significant cognitive decline. In this study we assessed neuropsychological functioning prospectively in newly diagnosed PCNSL patients treated with induction chemotherapy followed by reduced-dose WBRT. Twelve patients underwent neuropsychological evaluations at diagnosis, after induction chemotherapy, and 6 and 12 months after WBRT. Nine patients completed additional cognitive evaluations 18 and 24 months post-treatment. At diagnosis, patients had impairments in Executive Functions, Verbal Memory, and Motor Speed. There was a significant improvement in Executive Functions (P < 0.01) and Verbal Memory (P < 0.05) following induction chemotherapy, and scores remained relatively stable up to 12 months post-treatment. Among the nine patients who completed a 2-year follow-up, there was a significant improvement in the Executive domain (P < 0.05) and a trend toward a decline in the Verbal Memory domain. Executive and Verbal Memory functions improved following induction chemotherapy, likely due to decreased tumor burden and discontinuation of corticosteroid and anticonvulsant medications. There was no significant cognitive decline up to 24 months post-chemotherapy and reduced-dose WBRT in this group of PCNSL patients, however, difficulties in Verbal Memory and Motor speed persisted over the follow-up period.

[Cognitive disturbances observed in chronic hepatitis C patients during pegylated interferon alpha and ribavirin therapy]

Chronic hepatitis C (CHC) patients treated with peg-interferon alpha and ribavirin (peg-IFNalpha/RBV) complain of irritability, attention and memory disturbances which may indicate cognitive impairment associated with treatment.

AIM

Assessment of the probable connection between peg-IFNalpha/RBV treatment and the development of cognitive disturbances in CHC patients.

METHOD

47 CHC patients were divided into two groups: experimental (n=26) and control (n=21). The experimental group patients were given peg-IFNalpha2a (n=18) or peg-IFNalpha2b (n=8) plus RBV in standard doses as recommended by the manufacturers. Control group patients did not receive the above treatment. Both groups underwent a neuropsychological examination consisting of R. Brickenkamp d2 test, Auditory Verbal Learning Test and Hooper Visual Organization Test at the beginning (t=0) and after 12 weeks of treatment or observation (t=1).

RESULTS

The experimental group patients showed significant deterioration in all the measured cognitive functions in t=1 comparing to t=0. Cognitive decline was not seen in the control group. The observed cognitive performance changes could not be correlated sufficiently enough with the presence of organic affective disorders diagnosed according to ICD-10 criteria.

CONCLUSIONS

The findings suggest that peg-IFNalpha/RBV therapy of CHC patients is connected with the deterioration in cognitive functioning including attention, auditory verbal memory and visuo-spatial skills. These changes may be the effect of peg-IFNalpha-induced neurotransmission abnormalities in the dorso-lateral prefrontal cortex, anterior cingulate cortex, hippocampus and parieto-orbital cortical regions and can impair patients' ability to drive a motor vehicle, operate machinery, or their engagement in hazardous activities requiring attention and coordination. Medical professionals should thoroughly inform patients about the possibility of cognitive decline associated with peg-IFNalpha/RBV therapy.

Spatial working memory and problem solving in schizophrenia: the effect of symptom stabilization with atypical antipsychotic medication

Reasoning and problem solving in the spatial domain are important aspects of executive function that are reliably impaired in schizophrenia, and the Groton Maze Learning Test(c) (GMLT) provides a valid measure of spatial working memory. In the current study, 34 patients with first-episode schizophrenia and 20 matched controls were assessed for baseline spatial working memory abilities using this hidden maze learning test. Approximately one month after baseline assessment, allowing for symptoms to stabilize in response to treatment with therapeutic doses of atypical antipsychotic medications for individuals with schizophrenia, all participants were again assessed with the GMLT. Prior to pharmacologic intervention, patients with schizophrenia showed significant impairments in performance of all aspects of the GMLT, including measures of learning efficiency and error monitoring. One month of treatment was associated with a reliable improvement in these domains, although impairments in accuracy and error monitoring on this spatial working memory test persisted despite symptomatic improvement. These results indicate that impairments in spatial working memory are present at the earliest stages of the illness, and that such deficits in performance remain present, albeit ameliorated, after treatment with atypical antipsychotic medication.

Executive functioning component mechanisms and schizophrenia

BACKGROUND

Executive functioning refers to a set of processes involved in complex, goal-directed thought and behavior involving multiple brain regions (e.g., prefrontal cortex, parietal cortex, basal ganglia) and multiple neurotransmitters (e.g., dopamine, glutamate, gamma-aminobutyric acid). People with schizophrenia exhibit executive functioning deficits that are associated with treatment-refractory aspects of the disorder. Although there is general consensus about what cognitive tasks involve executive functioning, there is disagreement about the specific cognitive mechanisms that comprise executive functioning.

METHODS

This article discusses a number of possible candidate executive functioning mechanisms and provides a summary of the consensus reached by the executive functioning discussion group at the first CNTRICS (Cognitive Neuroscience for Treatment Research to Improve Cognition in Schizophrenia) meeting in Washington, DC.

RESULTS

The consensus was that two constructs have a well-founded basis in basic cognitive neuroscience research and seem to be impaired in schizophrenia: 1) rule generation and selection; and 2) dynamic adjustments in control (i.e., after conflict and errors).

CONCLUSIONS

The consensus of the first CNTRICS meeting was that immediate translation of measures of these constructs for use in schizophrenia should be pursued. A number of other constructs (e.g., scheduling, sequencing) could also be very important for schizophrenia and are in need of more basic and more clinical research.

Nicotine effects on retrieval-induced forgetting are not attributable to changes in arousal

BACKGROUND

There is emerging evidence from behavioural studies in humans for nicotinic modulation of inhibitory control. Administration of nicotine, however, also increases general arousal, and this may be responsible for the cognitive enhancing effects of nicotine.

DISCUSSION

To test an arousal explanation of nicotine's effects on cognitive inhibition, this study compared the separate and combined effects of an acute dose of nicotine and an arousal manipulation on inhibitory processes associated with the retrieval-induced forgetting (RIF) paradigm.

RESULTS

In a double blind placebo controlled design, 1.0 mg of nicotine delivered via nasal spray to non-smoking healthy young adults significantly increased the retrieval-induced forgetting observed in episodic list learning, relative to the placebo condition. In contrast, negative arousal evoked by an unsolvable anagram task had no effect either separately or in combination with nicotine.

CONCLUSION

This result argues against the attribution of nicotine-induced changes in RIF performance to non-specific arousal effects. It suggests, furthermore, that pharmacological manipulation of the RIF produces effects that are qualitatively distinct from mood-induced effects. We consider these changes to relate to the direct modulation of information processing by nicotine.

Apathy and the processing of novelty in schizophrenia

Apathy is a common negative symptom in schizophrenia that has been associated with poor medication compliance and treatment outcome. Recent studies in neurological patients have observed an association between apathy and reduced attention to novel stimuli. We evaluated whether patients with schizophrenia demonstrate a similar relationship. Participants included 20 patients with schizophrenia and 20 healthy comparison subjects matched for age, sex, handedness, and parental education. A self-paced visual novelty task was presented which assessed the duration that participants looked at frequent standard stimuli, infrequent target stimuli, and novel stimuli. Attention to novelty was defined as the duration of viewing novel relative to standard stimuli. Apathy was assessed with the Marin Apathy Evaluation Scale. Results revealed significantly greater self- and informant-reported apathy, slower reaction time to target stimuli, and longer viewing times to the stimuli, but not reduced attention to the novel stimuli, in the patient group. Although greater self-report of apathy was associated with longer viewing times for all stimuli in the patient group, this was accounted for by depressed mood. The present findings indicate that schizophrenia is associated with slowed information processing, but do not support the hypothesis that apathy in schizophrenia is associated with abnormal processing of novelty.

'Jumping to conclusions' and delusions in psychosis: relationship and response to treatment

'Jumping to conclusions' (JTC) on probabilistic reasoning tasks has been shown to be related with delusions in schizophrenia. However, whether JTC is merely correlated with, moderate or mediate delusions is not known. Further, it is unclear how antipsychotics affect JTC and its relationship to delusions. We examined the effect of treatment on JTC in a sample of patients (N=19) who were initiated on treatment and followed. Two versions of the task were used--the 'beads' version of the task and an emotionally salient version. Within two weeks of treatment, we found an increase in the number of trials to decision on the emotionally salient version and a reduction in intensity of psychotic symptoms and delusions (measured by the change on P1 and PANSS-P scores). While, these two measures, or changes in these measures, showed no reliable correlation, the baseline performance on the emotionally salient version of the task helped predict patients who would show improvements in their PANSS-P and global PANSS scores in response to medication. The findings suggest that JTC might moderate the effects of treatment on symptomatology, but it does not mediate the treatment induced reduction in delusional intensity.

Effects of lorazepam on deductive reasoning

RATIONALE

Benzodiazepines slow reasoning performance, but it is still unknown which phase of reasoning is affected and whether this effect is present for different types of relations between entities in reasoning problems.

OBJECTIVES

We investigated which phases of deductive reasoning are affected by lorazepam and whether this effect varies according to the type of relations in deductive reasoning problems.

METHODS

This was a double-blind, crossover design study of acute oral doses of lorazepam (2 mg) and placebo, using young healthy volunteers. We focused on response delay of three separable phases of deductive reasoning and matched working memory tasks (that involved only maintenance of information) the premise processing phase, the premise integration phase, and the validation phase, in which reasoners decide whether a conclusion logically follows from the premises (reasoning task) or is identical to one of the premises (maintenance task). Type of relations in the premises was also manipulated. We employed material that was difficult to envisage visually and visuospatially ("subiconic") and material easy to envisage visually or visuospatially.

RESULTS

Lorazepam slowed response as memory load increased, irrespective of type of relations. It also specifically slowed validation in reasoning problems with visual relations, an effect that disappeared after subtraction of maintenance scores, and increased validation time in problems with subiconic relations, which remained after this subtraction.

CONCLUSION

Acute lorazepam administration affected reasoning in two ways: it slowed processing nonspecifically when working memory demands increased and augmented validation time depending on the difficulty in generating and/or manipulating mental representations by the central executive.

The neuropsychological effects of chronic methylphenidate on drug-naive boys with attention-deficit/hyperactivity disorder

BACKGROUND

The reported neuropsychological effects of methylphenidate (MPH) in attention-deficit/hyperactivity disorder (ADHD) are inconsistent. The assumed relationships between these neuropsychological effects and clinical efficacy have not been substantiated. We therefore investigated the effects of chronic MPH administration on neuropsychological functioning.

METHODS

We conducted a 12-week, placebo-controlled, double-blinded, randomized, crossover trial (MPH .3 and .6 mg/kg/dose and placebo). Participants were 75 boys aged 7-15 years with ADHD. Neuropsychological performance was assessed with tests taken from the Cambridge Neuropsychological Test Automated Battery (CANTAB) battery and a GoNoGo task.

RESULTS

Chronic MPH improved performance (p < .001) on aspects of the GoNoGo task (p < .02) and on three CANTAB tasks which together contributed to a "recognition memory" component identified through principal components analysis (delayed matching to sample [DMtS], pattern and spatial recognition). There were no effects on other, high or low "executive demand" tasks (p > .05). GoNoGo performance improvements were the only neuropsychopharmacological changes associated with clinical response. Poor performance on the DMtS task was the sole baseline neuropsychological predictor of clinical response.

CONCLUSIONS

Chronic MPH predominantly enhanced neuropsychological functioning on "recognition memory" component tasks with modest "executive" demands. Neuropsychological measures offer only modest contributions to the prediction of clinical responses to MPH in ADHD.

Neurocognitive characterizations of Russian heroin addicts without a significant history of other drug use

Research on the neurocognitive characteristics of heroin addiction is sparse and studies that do exist include polydrug abusers; thus, they are unable to distinguish neurocognitive effects of heroin from those of other drugs. To identify neurocognitive correlates specific to heroin addiction, the present study was conducted in St. Petersburg, Russia where individuals typically abuse and/or become addicted to only one substance, generally alcohol or heroin. Heroin addicts were recruited from an inpatient treatment facility in St. Petersburg. Three comparison groups included alcoholics, addicts who used both alcohol and heroin, and non-abusers. Psychiatric, background, and drug history evaluations were administered after detoxification to screen for exclusion criteria and characterize the sample. Executive Cognitive Functions (ECF) that largely activate areas of the prefrontal cortex and its circuitry measured include complex visual pattern recognition (Paired Associates Learning), working memory (Delayed Matching to Sample), problem solving (Stockings of Cambridge), executive decision making (Cambridge Decision Making Task), cognitive flexibility (Stroop Color-Word Task) and response shifting (Stop Change Task). In many respects, the heroin addicts were similar to alcohol and alcohol+heroin dependent groups in neurocognitive deficits relative to controls. The primary finding was that heroin addicts exhibited significantly more disadvantageous decision making and longer deliberation times while making risky decisions than the other groups. Because the nature and degree of recovery from drug abuse are likely a function of the type or pattern of neurocognitive impairment, differential drug effects must be considered.

Ecological assessment of executive functions in substance dependent individuals

Substance dependence is associated with executive function deficits. However, most available studies have examined the performance of substance dependent individuals (SDI) on traditional laboratory measures of executive functions, whereas few studies have used ecologically valid assessments with SDI. Our aim was to examine the performance of 37 SDI (poly-substance users) and 37 matched controls on an ecologically valid measure of executive function (the Behavioural Assessment of the Dysexecutive Syndrome - BADS). We also administered the Wisconsin Card Sorting Test (WCST) to investigate whether ecological measures were more discriminative than traditional tests in detecting SDI deficits. A related aim was to examine the ability of the BADS (and the WCST) to predict everyday executive problems. Results showed that SDI had widespread deficits on ecological measures of executive function. Conversely, we found no differences between groups on the WCST. Furthermore, the BADS (but not the WCST) predicted everyday problems related to apathy, disinhibition, and executive dysfunction.

The neuropsychology of amphetamine and opiate dependence: implications for treatment

Chronic use of amphetamines and/or opiates has been associated with a wide range of cognitive deficits, involving domains of attention, inhibitory control, planning, decision-making, learning and memory. Although both amphetamine and opiate users show marked impairment in various aspects of cognitive function, the impairment profile is distinctly different according to the substance of abuse. In light of evidence showing that cognitive impairment in drug users has a negative impact on treatment engagement and efficacy, we review substance-specific deficits on executive and memory function, and discuss possibilities to address these during treatment intervention.

Sleep deprivation reduces perceived emotional intelligence and constructive thinking skills

BACKGROUND AND PURPOSE

Insufficient sleep can adversely affect a variety of cognitive abilities, ranging from simple alertness to higher-order executive functions. Although the effects of sleep loss on mood and cognition are well documented, there have been no controlled studies examining its effects on perceived emotional intelligence (EQ) and constructive thinking, abilities that require the integration of affect and cognition and are central to adaptive functioning.

PATIENTS AND METHODS

Twenty-six healthy volunteers completed the Bar-On Emotional Quotient Inventory (EQi) and the Constructive Thinking Inventory (CTI) at rested baseline and again after 55.5 and 58 h of continuous wakefulness, respectively.

RESULTS

Relative to baseline, sleep deprivation was associated with lower scores on Total EQ (decreased global emotional intelligence), Intrapersonal functioning (reduced self-regard, assertiveness, sense of independence, and self-actualization), Interpersonal functioning (reduced empathy toward others and quality of interpersonal relationships), Stress Management skills (reduced impulse control and difficulty with delay of gratification), and Behavioral Coping (reduced positive thinking and action orientation). Esoteric Thinking (greater reliance on formal superstitions and magical thinking processes) was increased.

CONCLUSIONS

These findings are consistent with the neurobehavioral model suggesting that sleep loss produces temporary changes in cerebral metabolism, cognition, emotion, and behavior consistent with mild prefrontal lobe dysfunction.

Effects of hormone replacement therapy and aging on cognition: evidence for executive dysfunction

The present study was designed to explore whether the frontal lobe hypothesis of cognitive aging may be extended to describe the cognitive effects associated with estrogen use in postmenopausal women. Postmenopausal estrogen-only users, estrogen + progesterone users, and non-users (60-80 years old), as well as young, regularly cycling women (18-30 years old) completed an item and source memory task. Since source memory is thought to rely more on executive processes than item memory, we hypothesized that aging and estrogen effects would be greater for source memory than for item memory. Neuropsychological tests explored whether the effects of aging and estrogen use were revealed on other tests of frontal lobe function. Results from the experimental task revealed greater aging and estrogen effects for source memory than for item memory, and neuropsychological results revealed aging and estrogen effects on a subset of tests of executive function. Women on estrogen + progesterone therapy did not outperform non-users, suggesting that the addition of progesterone to hormone therapy may mitigate the benefits induced by estrogen use alone. Overall, findings support the hypothesis that estrogen use may temper age-related cognitive decline by helping to maintain functions subserved by the frontal lobes.

Forecasting three-month outcomes in a laboratory school comparison of mixed amphetamine salts extended release (Adderall XR) and atomoxetine (Strattera) in school-aged children With ADHD

OBJECTIVE

Compare observed and forecasted efficacy of mixed amphetamine salts extended release (MAS-XR; Adderall) with atomoxetine (Strattera) in ADHD children.

METHOD

The authors analyze data from a randomized, double-blind, multicenter, parallel-group, forced-dose-escalation laboratory school study of children ages 6 to 12 with ADHD combined or hyperactive/impulsive type. Primary efficacy measures are attention and deportment scores on the SKAMP behavioral rating scale, and secondary efficacy measures are academic performance scores from the PERMP test.

RESULTS

MAS-XR elicits greater improvements than atomoxetine in each domain within 3 weeks of treatment, including attention, number of math problems attempted and correct, and overall clinical functioning. Treatment differences in each outcome measure at subsequent weeks are projected from generalized estimating equations to become greater with the duration of extension of the treatment regimen.

CONCLUSION

This study suggests that relative advantages of MAS-XR seen in the first 3 weeks are likely to be maintained in subsequent weeks.

Impaired verbal memory and otherwise spared cognition in remitted bipolar patients on monotherapy with lithium or valproate

OBJECTIVES

Patients with bipolar disorder have been reported to have neurocognitive deficits; however, it is not known whether the cognitive dysfunctions are state-dependent or a stable trait. Lithium and valproate, 2 of the most widely used mood stabilizers in the treatment of bipolar disorder, have also been associated with cognitive impairment. However, the degree and pattern of neurocognitive impairment in euthymic bipolar patients on either monotherapy with lithium or valproate have not been compared before in depth.

METHODS

We compared 17 euthymic outpatients with bipolar disorder (BD) on lithium monotherapy to 11 euthymic outpatients with BD on valproate monotherapy and 29 comparison subjects using tests measuring immediate verbal memory and executive functions in addition to 3 subtests of the Wechsler Adult Intelligence Scale Revised. The groups were similar in terms of level of education, duration and severity of illness, and gender distribution. Patients on lithium monotherapy were older than patients on valproate and healthy controls. Mood symptoms as assessed by standardized scales were mild to non-existent in both patient groups.

RESULTS

Immediate verbal memory was impaired in both patient groups compared to controls, where the main effect of age was not significant. No significant differences could be found on the other cognitive measures.

CONCLUSIONS

Both lithium and valproate may be associated with immediate verbal memory impairment, sparing other cognitive functions. Presence of a similar verbal memory deficit in the lithium and valproate groups suggests that this deficit might be intrinsic to BD or that the 2 medications influence immediate verbal memory similarly. Larger samples of remitted bipolar patients on monotherapy should be studied for more precise conclusions.

Maternal consumption of a docosahexaenoic acid-containing functional food during pregnancy: benefit for infant performance on problem-solving but not on recognition memory tasks at age 9 mo

BACKGROUND

There are few studies reporting on docosahexaenoic acid (DHA, 22:6n-3) supplementation during pregnancy and infant cognitive function. DHA supplementation in pregnancy and infant problem solving in the first year have not been investigated.

OBJECTIVE

We tested the hypothesis that infants born to women who consumed a DHA-containing functional food during pregnancy would demonstrate better problem-solving abilities and recognition memory than would infants born to women who consumed the placebo during pregnancy.

DESIGN

In a double-blind, placebo-controlled, randomized trial, pregnant women consumed a DHA-containing functional food or a placebo from gestation week 24 until delivery. Study groups received DHA-containing cereal-based bars (300 mg DHA/92-kcal bar; average consumption: 5 bars/wk; n = 14) or cereal-based placebo bars (n = 15). The Infant Planning Test and Fagan Test of Infant Intelligence were administered to infants at age 9 mo. The problem-solving trial included a support step and a search step. The procedure was scored on the basis of the infant's performance on each step and on the entire problem (intention score and total intentional solutions). Scores were generated on the basis of the cumulative performance of the infant on 5 trials.

RESULTS

Treatment had significant effects on the performance of problem-solving tasks: total intention score (P = 0.017), total intentional solutions (P = 0.011), and number of intentional solutions on both cloth (P = 0.008) and cover (P = 0.004) steps. There were no significant differences between groups in any measure of Fagan Test of Infant Intelligence.

CONCLUSION

These data point to a benefit for problem solving but not for recognition memory at age 9 mo in infants of mothers who consumed a DHA-containing functional food during pregnancy.

Neurobehavioral development in children with potential exposure to pesticides

BACKGROUND

Children may be at higher risk than adults from pesticide exposure, due to their rapidly developing physiology, unique behavioral patterns, and interactions with the physical environment. This preliminary study conducted in Ecuador examines the association between household and environmental risk factors for pesticide exposure and neurobehavioral development.

METHODS

We collected data over 6 months in the rural highland region of Cayambe, Ecuador (2003-2004). Children age 24-61 months residing in 3 communities were assessed with the Ages and Stages Questionnaire and the Visual Motor Integration Test. We gathered information on maternal health and work characteristics, the home and community environment, and child characteristics. Growth measurements and a hemoglobin finger-prick blood test were obtained. Multiple linear regression analyses were conducted.

RESULTS

Current maternal employment in the flower industry was associated with better developmental scores. Longer hours playing outdoors were associated with lower gross and fine motor and problem solving skills. Children who played with irrigation water scored lower on fine motor skills (8% decrease; 95% confidence interval = -9.31 to -0.53), problem-solving skills (7% decrease; -8.40 to -0.39), and Visual Motor Integration test scores (3% decrease; -12.00 to 1.08).

CONCLUSIONS

These results suggest that certain environmental risk factors for exposure to pesticides may affect child development, with contact with irrigation water of particular concern. However, the relationships between these risk factors and social characteristics are complex, as corporate agriculture may increase risk through pesticide exposure and environmental contamination, while indirectly promoting healthy development by providing health care, relatively higher salaries, and daycare options.

Prefrontal cognitive dysfunction following brainstem lesion

Prefrontal cortex (PFC) dysfunction can lead to impairment in planning and behavioral inhibition, as well as personality changes. As ascending monoaminergic brainstem systems modulate PFC functioning, it is possible that lesions in the brainstem lead to symptoms similar to prefrontal dysfunction. A 29-year-old man developed several cognitive and behavioral symptoms after neurosurgery for resection of a pilocytic astrocytoma in the pontine-mesencephalic area. A careful analysis of symptoms indicated PFC dysfunction that could be attributed to lesions in the ascending monoaminergic brainstem systems. Interestingly, the cognitive symptoms improved after treatment with methylphenidate, which is a drug that modules catecholaminergic neurotransmission, thereby supporting this hypothesis. This is a unique case of PFC dysfunction that may be related to post-operative lesion of the catecholaminergic nuclei in the brainstem.

Self-regulation of visual attention and facial expression of emotions in ADHD children

OBJECTIVE

To test if visual focusing and mimic display as features of self-regulation in ADHD children show a curvilinear relation to rising methylphenidate (MPH) doses. To test if small dose steps of 2.5mg MPH cause significant changes in behavior. And to test the relation of these features to intellectual performance, parents' ratings, and clinical outcome.

METHOD

Twenty-five children of a clinical convenience sample are filmed playing cards and doing oral arithmetic exercises without medication and after intake of MPH raised in steps of 2.5 mg. Recordings are revised by four blinded raters counting visual focus loss and rating the variability of patients' smile.

RESULTS

All hypotheses are confirmed. Best self-regulation coincides with best intellectual performance, highly significant improvement in parents' ratings, and good clinical outcome.

CONCLUSION

The procedure could be helpful for MPH dose finding in the physician's practice and make therapy more efficient by means of a more precise dosage.

Early initiation of L-dopa therapy enables stable development of executive function in tetrahydrobiopterin (BH4) deficiency

Executive function (EF) has been presumed to be mediated by the dopaminergic system in the prefrontal cortex. However, little is known about the early development of this function and the roles dopamine plays in it. Tetrahydrobiopterin (BH4) deficiencies are genetic disorders affecting catecholamine and serotonin biosynthesis which, if untreated, result in motor and cognitive symptoms including impairment of EF. A comprehensive neuropsychological test battery was administered to six participants with BH4 deficiency (four males, two females, mean Full-scale intelligence quotient [FIQ] 63.8 [SD 14.7]); all were on replacement therapy with L-dopa and BH4, but time of initiation of treatment varied. Age range (median) was 28 days to 41 years (2y 6mo) at initiation of treatment and 10 to 47 years (19y) at follow-up. On non-EF tests, performance agreed with those of IQ-matched controls (four males, two females; mean age 16y 6mo [SD 6mo]; mean FIQ 62.3 [SD 13.4]). On EF tests those who initiated treatment after 2 years 6 months of age performed poorly. In patients with BH4 deficiency, replacement therapy should be started in the first weeks or months of life. Patients diagnosed before the age of 2 years 6 months obtain normal EF, which suggests dopamine may play a critical role in ensuring stable development of EF in early life.

Problem-solving ability and comorbid personality disorders in depressed outpatients

Major depressive disorder (MDD) is associated with poor problem-solving abilities. In addition, certain personality disorders (PDs) that are common among patients with MDD are also associated with limited problem-solving skills. Attempts to understand the relationship between PDs and problem solving can be complicated by the presence of acute MDD. Our objective in this study was to investigate the relationships between PDs, problem-solving skills, and response to treatment among outpatients with MDD. We enrolled 312 outpatients with MDD in an open, fixed-dose, 8-week fluoxetine trial. PD diagnoses were ascertained via structured clinical interview before and after fluoxetine treatment. Subjects completed the Problem-Solving Inventory (PSI) at both time points. We used analyses of covariance (ANCOVAs) to assess relationships between PD diagnoses and PSI scores prior to treatment. Subjects were divided into three groups: those with PD diagnoses that remained stable after fluoxetine treatment (N=91), those who no longer met PD criteria after fluoxetine treatment (N=119), and those who did not meet criteria for a PD at any time point in the study (N=95). We used multiple chi(2) analyses to compare rates of MDD response and remission between the three PD groups. ANCOVA was also used to compare posttreatment PSI scores between PD groups. Prior to fluoxetine treatment, patients with avoidant, dependent, narcissistic, and borderline PDs reported significantly worse problem-solving ability than did patients without any PDs. Only subjects with dependent PD remained associated with poorer baseline problem-solving reports after the effects of baseline depression severity were controlled. Patients with stable PD diagnoses had significantly lower rates of MDD remission. Across PD groups, problem solving improved as MDD improved. No significant differences in posttreatment problem-solving were found between PD groups after controlling for baseline depression severity, baseline PSI score, and response to treatment. Treatment with fluoxetine is less likely to lead to remission of MDD in patients with stable PDs. More study is needed to investigate causal links between PDs, problem solving, and MDD treatment response.

The effect of alpha-2 adrenergic agonists on memory and cognitive flexibility

BACKGROUND

The noradrenergic system modulates cognitive flexibility for insight-based problem solving in studies using beta-adrenergic antagonists, which block noradrenergic neurotransmission postsynaptically. However, it is not known whether alpha2-adrenergic agonists, that decrease noradrenergic neurotransmission by presynaptic inhibition, have the same effect.

OBJECTIVES

Therefore, we wished to test whether alpha2-adrenergic agonists would have a similar effect on cognitive flexibility.

METHODS

Eighteen normal adults were tested on cognitive flexibility, problem solving, verbal and spatial memory tasks after receiving clonidine (0.1 mg), an alpha2-agonist, placebo, or ephedrine (25 mg), a noradrenergic stimulant.

RESULTS

Three-way analysis of variance revealed no significant drug effect on cognitive flexibility or problem solving. There was also no significant effect of clonidine on memory.

CONCLUSIONS

Therefore, alpha2-agonists do not influence cognitive flexibility in the same manner as beta-antagonists. Better performance on memory with clonidine might be expected based on primate studies demonstrating benefits in working memory using clonidine. This benefit was not observed for the commonly used clinical memory tasks in our study. This may have implications for why clonidine has not demonstrated efficacy for cognitive disorders such as Alzheimer disease, despite its known benefit for working memory in animal models.

Lack of deleterious effects of buspirone on cognition in healthy male volunteers

Buspirone is a serotonin 5-HT(1A) receptor agonist licensed for the treatment of anxiety. Other anxiolytic drugs such as benzodiazepines show significant sedative and other unwanted effects on cognition. Studies to date have yet to investigate cognitive effects of buspirone using well-validated computerized tests. The aim of this study was to assess acute subjective and cognitive effects of buspirone in healthy volunteers. Sixty healthy male volunteers received 20 mg buspirone, 30 mg buspirone, or placebo per os in a double-blind parallel groups design (N=20 per group). Subjective ratings (visual analogue scales) were completed at baseline, and at 1.5 and 3.5 hours post-capsule. Cognitive assessment was undertaken between 1.5 and 3.5 hours post-capsule, including tests of memory, executive planning, impulse control, decision making and cognitive flexibility. The 30 mg buspirone group showed significantly higher subjective ratings of contentedness 3.5 hours after capsule relative to placebo. Treatment and placebo groups did not differ significantly on cognitive measures. In contrast to benzodiazepines, the anxiolytic buspirone appears to lack detectable deleterious effects on cognition when administered acutely at clinically meaningful doses. Future research directions are discussed in relation to acute and chronic studies in neuropsychiatric populations.

The effects of chewing versus caffeine on alertness, cognitive performance and cardiac autonomic activity during sleep deprivation

Chewing has been shown to alleviate feelings of sleepiness and improve cognitive performance during the day. This study investigated the effect of chewing on alertness and cognitive performance across one night without sleep as well as the possible mediating role of cardiac autonomic activity. Fourteen adults participated in a randomized, counterbalanced protocol employing a chewing, placebo and caffeine condition. Participants completed tasks assessing psychomotor vigilance, tracking, grammatical reasoning, alertness and sleepiness each hour across the night. All participants received either placebo or caffeine (200 mg), while the chewing condition also chewed on a tasteless and odorless substance for 15 min each hour. Heart rate (HR), root mean square of the successive differences in R-R intervals on the ECG (RMSSD), and preejection period (PEP) were simultaneously recorded. Alertness and cognitive performance amongst the chewing condition did not differ or were in fact worse when compared with placebo. Similarly, measures of HR and RMSSD remained the same between these two conditions; however, PEP was reduced in the later part of the night in the chewing condition compared with a relative increase for placebo. Caffeine led to improved speed and accuracy on cognitive tasks and increased alertness when compared with chewing. Relative increases in RMSSD and reductions in HR were demonstrated following caffeine; however, no change in PEP was seen. Strong associations between cardiac parasympathetic activity and complex cognitive tasks, as well as between subjective alertness and simpler cognitive tasks, suggest a differential process mediating complex versus simple cognitive performance during sleep deprivation.

Effects of levodopa and subthalamic nucleus stimulation on cognitive and affective functioning in Parkinson's disease

In Parkinson's disease (PD), levodopa and subthalamic nucleus (STN) stimulation lead to major improvement in motor symptoms. Effects of both treatments on cognition and affective status are less well understood. Motor, cognitive, and affective symptoms may relate to the dysfunctioning of parallel cortico-striatal loops. The aim of this study was to assess cognition, behavior, and mood, with and without both treatments in the same group of PD patients. A group of 22 nondemented PD patients was included in this study. Patients were tested twice before surgery (off and on levodopa) and twice 3 months after surgery (OFF and ON STN stimulation, off levodopa). Cognitive and affective effects of STN stimulation and levodopa had some common, but also different, effects. STN stimulation improved performance on the planning test, associated with the dorsolateral prefrontal cortex. However, the treatments had opposite effects on tests associated with the orbitofrontal cortex; specifically, levodopa impaired while STN stimulation improved performance on the extinction phase of a reversal/extinction task. Acutely, both treatments improved motivation and decreased fatigue and anxiety. On chronic treatment (3 months after surgery), depression improved, whereas apathy worsened 3 months after surgery. To conclude, there were significant but contrasting effects of levodopa and STN stimulation on cognition and affective functions.

Strategic Subcortical Hyperintensities in Cholinergic Pathways and Executive Function Decline in Treated Alzheimer Patients

OBJECTIVE

To investigate changes in cognition, function, and behavior after 1 year in patients with Alzheimer disease being treated with cholinesterase inhibitors, in relation to the presence or absence of subcortical hyperintensities involving the cholinergic pathways.

DESIGN

One-year prospective cohort study.

SETTING

Memory Clinic, Sunnybrook Health Sciences Centre, University of Toronto. Patients Ninety patients with possible/probable Alzheimer disease who were being treated with cholinesterase inhibitors at baseline.

INTERVENTIONS

Yearly standardized neuropsychological testing and brain magnetic resonance imaging (MRI). The Cholinergic Pathways Hyperintensities Scale (CHIPS) was applied to baseline MRIs to rate the severity of subcortical hyperintensities in cholinergic pathways. The consensus-derived Age-Related White Matter Changes (ARWMC) Rating Scale was used as a general measure of white matter disease burden.

MAIN OUTCOME MEASURES

Tests of global cognition, function, and behavior and specific cognitive and functional domains.

RESULTS

Patients in the low CHIPS group were equivalent to those in the high CHIPS group with regard to baseline demographic characteristics, cognitive severity, and vascular risk factors. After covarying age and education, no differences were found after 1 year in overall cognition, function, and behavior or on memory, language, and visuospatial tasks. Patients in the high CHIPS group showed improvement on executive function and working memory tasks compared with those in the low CHIPS group. For the ARWMC scale, groups with and without white matter abnormalities were equivalent on baseline demographics and in cognitive, functional, and behavioral outcomes.

CONCLUSION

Cerebrovascular compromise of the cholinergic pathways may be a factor that contributes more selectively than does total white matter lesion burden to response to cholinergic therapy in Alzheimer disease, particularly on frontal/executive tasks.

Cardiovascular reactivity to mental stress is not affected by alpha2-adrenoreceptor activation or inhibition

RATIONALE

It has been postulated that cardiovascular reactivity to mental stress varies with tonic central sympathetic nervous system activity, but pharmacological evidence is missing.

OBJECTIVE

To test whether modulation of central sympathetic nervous system activity by alpha2-adrenergic agonism and antagonism affects cardiovascular reactivity to mental stress.

MATERIALS AND METHODS

On three five-stepped dose/concentration-response study days, 12 healthy male volunteers received intravenous infusions of dexmedetomidine (alpha2-agonist, target plasma concentrations: 0.04-0.32 ng/ml), yohimbine (alpha2-antagonist, doses: 0.016-0.125 mg/kg), and placebo, respectively. During each dose step, subjects performed a 5-Choice Reaction Time Task (CRTT) and a Paced Auditory Serial Addition Task (PASAT) to induce moderate mental stress. Prestress baseline, as well as stress-induced responses of heart rate, and noninvasive finger arterial blood pressure (Finapres) were assessed.

RESULTS

Prestress baseline heart rate and blood pressure decreased with increasing doses of dexmedetomidine and increased with increasing doses of yohimbine. However, dexmedetomidine and yohimbine did not affect stress-induced heart-rate and blood-pressure changes.

CONCLUSIONS

Cardiovascular reactivity to mental stress is not related to pharmacologically manipulated tonic central sympathetic nervous system activity by alpha2-adrenergic agonists and antagonists. These results do not support the assumption that cardiovascular reactivity is an index of tonic central sympathetic nervous system activity.

COMT val108/158met genotype, cognitive function, and cognitive improvement with clozapine in schizophrenia

Preliminary evidence suggests that a single nucleotide polymorphism (SNP), the val108/158met SNP, within the gene that codes for catechol-O-methyltransferase (COMT), a key enzyme involved in regulating dopamine (DA) transmission within the prefrontal cortex (PFC), is related to cognitive function in schizophrenia and cognitive improvement with atypical antipsychotic drugs (APDs). Specifically, several studies have identified an association between working memory and executive functions, and COMT val108/158met genotype in schizophrenia; although there have been several negative findings that are likely related to small sample sizes and, possibly, medication status of patients at the time of testing. The association between COMT val108/158met genotype, cognitive function, and cognitive improvement with clozapine was investigated in a relatively large prospective sample of patients with schizophrenia, most of whom were unmedicated at baseline. Patients were genotyped for the COMT val108/158met SNP after completing a cognitive battery consisting of tests of attention, working memory, verbal learning and memory, executive function, and verbal fluency at baseline and after 6 weeks and 6 months of treatment with clozapine. Consistent with several previous studies, an association between COMT genotype and tests of executive function and working memory was identified at baseline. In addition, a novel interaction between genotype and improvement on tests of attention and verbal fluency was identified. Specifically, met homozygous and val/met heterozygous patients demonstrated significantly greater improvement than val homozygous patients following 6 months of treatment with clozapine. The results are discussed in relation to previous cross-sectional studies and prospective investigations of the associations between COMT genotype, cognition, and cognitive improvement with atypical APDs in schizophrenia.

Cognitive performance following premature awakening from zolpidem or melatonin induced daytime sleep

BACKGROUND

The hypnotic zolpidem and the hormone melatonin were evaluated and directly compared for their effects on performance when subjects sleeping under their influence were prematurely awakened from daytime sleep.

METHOD

Non-sleep deprived volunteers (eight men and five women) received single oral doses of 5 or 10 mg melatonin (Mel-5; Mel-10), 10 or 20 mg zolpidem (Zol-10; Zol-20), or placebo immediately before retiring at 13:00. Performance testing and subjective evaluations occurred prior to dosing and following forced awakening at 15:00, 2 h after dosing.

RESULTS

Compared with placebo, on being awakened under Zol-20, significant performance decrements were prevalent on 9 of 10 cognitive tasks, including grammatical reasoning, mathematical processing, and word memory. Recovery required up to 6 h post-awakening for the more complex tasks. Loss of coordination and nausea were also present on awakening under Zol-20. On being awakened under Zol-10, significant but relatively less severe and shorter duration performance decrements occurred for 4 of the 10 tasks and recovered by 4 h post-awakening. Under Mel-5 or Mel-10, performance decrements seldom occurred and were considerably less severe, briefer, and less systematic than for zolpidem.

CONCLUSION

Findings indicated that when operational personnel sleeping with the aid of either 10 or 20 mg zolpidem are prematurely awakened, it would be prudent to evaluate their general well-being and possible need for assistance prior to their being permitted to depart crew-rest or to perform tasks and duties. In contrast, we found little to no evidence of deteriorated well-being or need for assistance when awakened while sleeping under the influence of melatonin.

MDMA use and neurocognition: a meta-analytic review

RATIONALE

To determine the association between MDMA misuse and neurocognition using meta-analysis.

OBJECTIVE

Separate analyses were conducted based on two sets of inclusion/exclusion criteria. A relatively stringent set required that the subjects be matched on important moderator variables, whereas the other did not. The study participants' performance in the following neurocognitive domains was reviewed: attention/concentration, verbal and nonverbal learning and memory, psychomotor speed and executive systems functioning.

RESULTS

In the 11 studies meeting the relatively stringent inclusion/exclusion criteria for this review, MDMA use was associated with neurocognitive deficits in each domain. Similarly, in the 23 studies meeting the relatively lenient inclusion/exclusion criteria for this review, MDMA use was associated with neurocognitive deficits in each domain. Small to medium effect sizes were generally observed. A comparison of the effect sizes across the two sets of analyses did not reveal significant differences.

CONCLUSIONS

The findings from this review reveal that MDMA use is associated with neurocognitive deficits. The implications of these findings are discussed.

Reactivity and regulation in children prenatally exposed to cocaine

Children prenatally exposed to cocaine may be at elevated risk for adjustment problems in early development because of greater reactivity and reduced regulation during challenging tasks. Few studies have examined whether cocaine-exposed children show such difficulties during the preschool years, a period marked by increased social and cognitive demands and by rapid changes in reactivity and regulation. The authors addressed this question by examining frustration reactivity and regulation of behavior during a problem-solving task in cocaine-exposed and -unexposed preschoolers. Participants were 174 4.5-year-olds (M age = 4.55 years, SD = 0.09). Frustration reactivity was measured as latency to show frustration and number of disruptive behaviors, whereas regulation was measured as latency to approach and attempt the problem-solving task and number of problem-solving behaviors. Results indicated that cocaine-exposed children took longer to attempt the problem-solving task but that cocaine-exposed boys showed the most difficulties: They were quicker to express frustration and were more disruptive. Effect sizes were relatively small, suggesting both resilience and vulnerabilities.

Long-term cognitive impact of anticholinergic medications in older adults

OBJECTIVE

The objective of this study was to determine whether chronic use of medications with anticholinergic (AC) properties impact older adults' cognitive functioning.

METHODS

Six years of cognitive test data from two groups of older adults (AC and control) were examined retrospectively (N = 592).

RESULTS

Declines over time were found for the AC group on parts A and B of the Trail Making Test.

CONCLUSION

Physicians prescribing ACs to older adult patients should be aware of their potential effects on psychomotor speed and executive functioning. These cognitive effects may lead to impairments in daily functioning resulting in the need to reevaluate patient medications.

Acute neuropsychological effects of methylphenidate in stimulant drug-naïve boys with ADHD II--broader executive and non-executive domains

BACKGROUND

Accumulating evidence supports methylphenidate-induced enhancement of neuropsychological functioning in attention deficit hyperactivity disorder (ADHD). The present study was designed to investigate the acute effects of the psychostimulant drug, methylphenidate (MPH), on neuropsychological performance in stimulant naïve boys with ADHD.

METHODS

Seventy-three drug-naïve boys (age 7-15) with ADHD (combined type) completed neuropsychological tasks from the CANTAB battery under randomised, placebo controlled, double-blind conditions following an acute challenge with either placebo (n = 24), .3 (n = 25) or .6 (n = 24) mg/kg oral MPH.

RESULTS

MPH did not impair performance on any task. MPH (.6 mg/kg) lengthened response latencies on a task of Spatial Recognition, shortened response times on a Reaction Time task and restored performance on a Delayed Matching to Sample visual, non-working memory task. Contrary to predictions, MPH did not enhance performance on tasks with a prominent executive component, including Go/NoGo, Spatial Working Memory, Stockings of Cambridge and Attentional Set shifting tasks.

CONCLUSIONS

Acute administration of MPH to drug-naïve boys with ADHD did not impair neuropsychological performance. Acute MPH enhanced performance on some aspects of non-executive functioning. MPH-induced slowing of responding on a relatively complex Spatial Recognition memory task and quickened responding on a reaction time task requiring less cognitive resources suggests that MPH may act by improving self-regulatory ability. MPH may not exert its effects on neuropsychological functioning by enhancing executive processes.

Effects of nicotinic therapies on attention and executive functions in chronic low-dose MPTP-treated monkeys

Chronic administration of low doses of the neurotoxin MPTP to nonhuman primates induces cognitive deficits similar to those seen in early Parkinson's disease (PD) patients, without the confounding effect of significant motor impairment. The present study assessed the extent to which specific attentional and central executive deficits in chronic low dose (CLD) MPTP-treated monkeys could be modified by nicotinic therapies. Four adult male rhesus monkeys were trained to perform attention and executive function tasks and were then administered low doses of MPTP (dose range: 0.025-0.1 mg/kg, i.v.) over 98-158 days until stable cognitive deficits appeared. Results showed that both nicotine and the alpha4beta4 subtype-selective nAChR agonist SIB-1553A could improve certain aspects of attentional and central executive functioning in this model of early Parkinsonism. Nicotine failed to improve performance of CLD-MPTP-treated animals on an attention set-shifting task while SIB-1553A significantly improved at least some aspects of performance, suggesting that the compound increased the animals' ability to maintain a previously formed response set and restored cognitive flexibility. Both nicotine and SIB-1553A caused a dose-dependent enhancement of performance on the focused attention (cued reaction time) task, decreasing reaction times on both cued and noncued trials. Nicotine caused a significant reduction in reaction times but did not alter the error profile on an impulse (motor readiness) task. SIB-1553A reduced reaction times but caused an increase in bar release (i.e. impulsivity) errors. These data suggest that nicotinic drugs may have therapeutic potential for treating cognitive dysfunction in PD.

High-potency marijuana impairs executive function and inhibitory motor control

Human performance studies have usually relied on low-potency marijuana (4% THC) for determining THC-induced impairment. The present study was designed to assess the effects of high-potency marijuana (13% THC) on human performance. In all, 20 recreational users of marijuana participated in a double-blind, placebo controlled, three way cross-over study. The treatments consisted of single doses of 0, 250, and 500 microg/kg THC. Performance tests were conducted at regular intervals between 15 min and 6 h postsmoking and included measures of motor control (Critical tracking task), executive function (Tower of London) motor impulsivity (Stop signal task), and risk taking (Iowa gambling task). THC significantly impaired performance in the Critical tracking task and decreased the number of correct decisions in the Tower of London task. In addition, THC significantly increased stop reaction time and the proportions of commission and omission errors in the Stop signal task. THC-induced impairments lasted up to 6 h postsmoking as indicated by the absence of a THC x Time after smoking interaction. Effect sizes for performance impairments produced by THC 250 microg/kg were relatively low but generally increased by a factor of two in case of THC 500 microg/kg. These data suggest that high potency marijuana consistently impairs executive function and motor control. Use of higher doses of THC in controlled studies may offer a reliable indication of THC induced impairment as compared to lower doses of THC that have traditionally been used in performance studies.