751 research outputs found
Comparable effects of nicotine in smokers and nonsmokers on a prospective memory task.
In a double-blind placebo-controlled study, we examined the effect of nicotine, a cholinergic agonist, on performance of a prospective memory (ProM) task in young adult volunteers. Volunteers were required to complete an ongoing lexical decision task while maintaining the ProM task (responding with a different button press to items containing particular target letters). Half of the volunteers were smokers, half were nonsmokers. Half of each group received a single dose (1 mg) of nicotine nasal spray before completing the task; the remaining volunteers received a matched inactive placebo spray. Nicotine improved performance on the ProM task when volunteers were able to devote resources to that task. Under a variant procedure, where volunteers completed a concurrent auditory monitoring task, ProM performance was impaired under nicotine. Results are discussed in terms of the resource model of ProM, and the arousal model of drug effects. The data suggest that ProM under the conditions tested here is a resource-needy process, and that nicotine can improve performance by increasing available resources. Increased working memory demands that encourage redirection of resources may impair ProM performance, but the conditions under which these deficits emerge depend upon the subjective allocation of resources across tasks, rather than resource availability per se
Investigating the impact of nicotine on executive functions using a novel virtual reality assessment
Aims Nicotine is known to enhance aspects of cognitive functioning in abstinent smokers but the effects on specific areas of executive functions, and in non-smokers are inconclusive. This may be due in part to the poor sensitivity of tests used to assess executive functions. This study used a new virtual reality assessment of executive functions known as JEF (the Jansari assessment of Executive Functions) to address this issue. Design 2x2 design manipulating group (smokers and never-smokers) and drug (nicotine [4mg for smokers; 2mg for never smokers] vs placebo gum). Setting School of Psychology; University of East LondonParticipants 72 participants (aged 18 to 54). 36 minimally-deprived (2 hr) smokers and 36 never-smokers.Measurements Components of executive function were measured using the virtual reality paradigm JEF, which assesses eight cognitive constructs simultaneously as well as providing an overall performance measure. Results Univariate ANOVAs revealed that nicotine improved overall JEF performance, time-based prospective memory and event-based prospective memory in smokers (p < 0.01) but not in never-smokers. Action-based prospective memory was enhanced in both groups (p < 0.01) and never-smokers out-performed smokers on selective thinking and adaptive thinking (p < 0.01). Conclusions. Overall executive functioning and prospective memory can be enhanced by nicotine gum in abstinent smokers. That smokers were only minimally deprived suggests that JEFis a sensitive measure of executive functioning and that prospective memory is particularly susceptible to disruption by abstinence
Affective problems and decline in cognitive state in older adults: a systematic review and meta-analysis
Evidence suggests that affective problems, such as depression and anxiety, increase risk for late-life dementia. However, the extent to which affective problems influence cognitive decline, even many years prior to clinical diagnosis of dementia, is not clear. The present study systematically reviews and synthesises the evidence for the association between affective problems and decline in cognitive state (i.e. decline in non-specific cognitive function) in older adults. An electronic search of PubMed, PsycInfo and ScienceDirect was conducted to identify studies of the association between depression and anxiety separately and decline in cognitive state. Key inclusion criteria were prospective, longitudinal designs with a minimum follow-up period of one year. Data extraction and methodological quality assessment using the STROBE checklist were conducted independently by two raters. A total of 34 studies (n=71,244) met eligibility criteria, with 32 studies measuring depression (n=68,793), and 5 measuring anxiety (n=4,698). A multi-level meta-analysis revealed that depression assessed as a binary predictor (OR=1.36, 95% CIs: 1.05-1.76, p=.02) or a continuous predictor (B=-0.008, 95% CIs: -0.015, -0.002, p=.012; OR=0.992, 95% CIs: 0.985-0.998) was significantly associated with decline in cognitive state. The number of anxiety studies were insufficient for meta-analysis and are instead described in a narrative review. Results of the present study improve current understanding of the temporal nature of the association between affective problems and decline in cognitive state. They also suggest that cognitive function need to be monitored closely in individuals with affective disorders, as these individuals may be at a particular risk of greater cognitive decline
The APOE paradox: how do attentional control differences in mid-adulthood reflect risk of late-life cognitive decline
Possession of an APOE e4 allele is an established risk factor for Alzheimer’s disease, while the less commonly studied e2 variant is premised to offer some protection. This research explores the purported deleterious-protective dichotomy of APOE variants on attentional control in mid-adulthood. 66 volunteers, aged 45-55 years, completed three tasks that provided complementary measures of attentional control: prospective memory, sustained attention and inhibition. Performance was compared between e2 carriers, e4 carriers and e3 homozygotes (the population norm). Carriers of the e4 allele showed subtle disadvantages, compared to the e3 group, in accuracy of Stroop task and prospective memory performance. Contrary to expectations, e2 carriers showed performance disadvantages in sustained attention. The finding of detrimental effects in attentional control for both e4 and e2 complicates the current model that proposes opposing effects of these variants on later-life cognition. Future research is needed to understand how cognitive differences develop with increasing age, and the physiological mechanisms that underpin these changes
Cognitive impairment in HIV and HCV co-infected patients: a systematic review and meta-analysis
Cognitive impairment has been well documented in human immunodeficiency virus (HIV) and hepatitis C virus (HCV) mono-infections. However, in the context of HIV/HCV co-infection the research is more limited. The aim of this systematic review was to describe the characteristics of cognitive impairment in HIV/HCV co-infection and to examine the differences in cognitive performance between HIV/HCV and HIV and HCV mono-infected patients. Of the 437 records initially screened, 24 papers met the inclusion criteria and were included in the systematic review. Four studies were included in the meta-analysis. Most studies indicated that HIV/HCV co-infected patients had a higher level of cognitive impairment than HIV mono-infected patients. Meta-analysis also indicated that HIV mono-infected patients had a significantly lower global deficit score than co-infected patients. The results also indicated that co-infected patients were more likely to be impaired in information processing speed than HIV mono-infected patients. These findings can be challenged by biasing factors such as the small number of included studies, heterogeneity of the samples and a large diversity of methodological procedures. Future research with consistent and comprehensive neuropsychological batteries and covering a greater diversity of risk factors is needed, in order to clarify the effects of both viruses on cognitive function and the mechanisms that underlie these effects. Because cognitive impairments may pose significant challenges to medication adherence, quality of life and overall functioning, such knowledge may have important implications to the planning and implementation of effective interventions aimed at optimising the clinical management of these infections
The elusive nature of APOE ε4 in mid-adulthood: understanding the cognitive profile
Objectives: The apolipoprotein E (APOE) ε4 allele is an established risk factor for dementia, yet this genetic variant is associated with a mixed cognitive profile across the lifespan. This study undertakes both a systematic and meta-analytic review of research investigating APOE-related differences in cognition in mid-adulthood, when detrimental effects of the allele may first be detectable.
Methods: Thirty-six papers investigating the behavioral effects of APOE ε4 in mid-adulthood (defined as a mean sample age between 35 and 60 years) were reviewed. In addition, the effect of carrying an ε4 allele on individual cognitive domains was assessed in separate meta-analyses.
Results: The average effect size of APOE ε4 status was non-significant across cognitive domains. Further consideration of genotype effects indicates preclinical effects of APOE ε4 may be observable in memory and executive functioning.
Conclusions: The cognitive profile of APOE ε4 carriers at mid-age remains elusive. Although there is support for comparable performance by ε4 and non-e4 carriers in the 5th decade, studies administering sensitive cognitive paradigms indicate a more nuanced profile of cognitive differences. Methodological issues in this field preclude strong conclusions, which future research must address, as well as considering the influence of further vulnerability factors on genotype effects
Depression in HIV and HCV co-infected patients: a systematic review and meta-analysis
The aim of this study was to carry out a systematic review and meta-analysis of the differences in the prevalence of depression and presence of depressive symptoms between HIV/HCV co-infection, HIV mono-infection, and hepatitis C virus (HCV) mono-infection. A systematic electronic search of bibliographic databases was performed to locate articles published from the earliest available online until December 2014. Outcomes of depression were based on clinical interviews and validated self-reported measures of depression/depressive symptoms. Of the 188 records initially screened, 29 articles were included in the descriptive systematic review and six were included in the meta-analysis. The meta-analytic results indicated that, as measured by self-reported measures of depression, HIV/HCV co-infected patients were significantly more likely to report depressive symptoms than either HIV (SMD = .24, 95% CI: .03-.46, p = .02) or HCV mono-infected (SMD = .55, 95% CI: .17-.94, p = .005) patients. The variability of the results of the reviewed studies, largely dependent on the samples' characteristics and the methods of assessment of depression, suggests that a clear interpretation of how depression outcomes are affected by the presence of HIV/HCV co-infection is still needed. Failing to diagnose depression or to early screen depressive symptoms may have a significant impact on patients' overall functioning and compromise treatments' outcomes
Long-term high-effort endurance exercise in older adults: diminishing returns for cognitive and brain aging
While there is evidence that age-related changes in cognitive performance and brain structure can be offset by increased exercise, little is known about the impact on these of long-term high-effort endurance exercise. In a cross-sectional design with 12-month follow-up, we recruited older adults engaging in high-effort endurance exercise over at least twenty years, and compared their cognitive performance and brain structure with a non-sedentary control group similar in age, sex, education, IQ, and lifestyle factors. Our findings showed no differences on measures of speed of processing, executive function, incidental memory, episodic memory, working memory, or visual search for older adults participating in long-term high-effort endurance exercise, when compared without confounds to non-sedentary peers. On tasks that engaged significant attentional control, subtle differences emerged. On indices of brain structure, long-term exercisers displayed higher white matter axial diffusivity than their age-matched peers, but this did not correlate with indices of cognitive performance
A longitudinal study assessing depression in hepatitis C: does gender play a role in the new onset depression during interferon-alpha treatment?
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