Alexandra L. Seddon

Bio: Alexandra L. Seddon is an academic researcher from Liverpool John Moores University. The author has contributed to research in topics: Cognitive flexibility & Human multitasking. The author has an hindex of 3, co-authored 5 publications receiving 99 citations. Previous affiliations of Alexandra L. Seddon include Liverpool School of Tropical Medicine.

Cannabis‐related deficits in real‐world memory

Abstract: Background Research shows that cannabis users exhibit deficits in prospective memory (PM) and executive function, which persist beyond acute intoxication. However, many studies rely on self-reports of memory failures or use laboratory-based measures that may not mimic functional deficits in the real world. The present study aimed to assess real-world memory functioning. Method Twenty cannabis-only users and 20 non-illicit drug users were recruited. Participants completed a substance use inventory and a mood scale, followed by a non-immersive virtual reality task assessing PM and executive functioning. The task involved the participant playing the role of an office worker for the day and performing routine office duties. A number of subscales were used to assess facets of executive function (planning, adaptive thinking, creative thinking, selection, prioritisation) and PM (time-based, event-based and action-based PM). Results Multivariate analysis of variance revealed cannabis users performed worse overall on the task, with poor performance on the planning, time-based PM and event-based PM subscales. In addition, indices of cannabis (length, dose, frequency, total use) were correlated with performance on these three subscales. Conclusions The present study expands on previously established research, providing support for the cannabis-related deficits in PM and executive functioning, and the role of different aspects of cannabis use in these deficits.

Novel Analysis of Immune Cells from Nasal Microbiopsy Demonstrates Reliable, Reproducible Data for Immune Populations, and Superior Cytokine Detection Compared to Nasal Wash.

Abstract: The morbidity and mortality related to respiratory tract diseases is enormous, with hundreds of millions of individuals afflicted and four million people dying each year. Understanding the immunological processes in the mucosa that govern outcome following pathogenic encounter could lead to novel therapies. There is a need to study responses at mucosal surfaces in humans for two reasons: (i) Immunological findings in mice, or other animals, often fail to translate to humans. (ii) Compartmentalization of the immune system dictates a need to study sites where pathogens reside. In this manuscript, we describe two novel non-invasive nasal mucosal microsampling techniques and their use for measuring immunological parameters: 1) using nasal curettes to collect cells from the inferior turbinate and; 2) absorptive matrices to collect nasal lining fluid. Both techniques were well tolerated and yielded reproducible and robust data. We demonstrated differences in immune populations and activation state in nasal mucosa compared to blood as well as compared to nasopharyngeal lumen in healthy adults. We also found superior cytokine detection with absorptive matrices compared to nasal wash. These techniques are promising new tools that will facilitate studies of the immunological signatures underlying susceptibility and resistance to respiratory infections.

Exploring the relationship between executive functions and self-reported media-multitasking in young adults

Abstract: Media-multitasking involves simultaneous engagement with information streams from multiple media sources, and is most prevalent in young adults. Heavy media-multitasking has been associated with differential performance on tasks involving attentional control and working memory relative to light media-multitasking. The aim of the present study was to systematically investigate relationships between executive functions and self-reported media-multitasking. Healthy participants (N = 112, aged 18–25, male N = 36) completed a battery of 10 traditional executive function tasks, that included assessments of attentional inhibition, response inhibition, working memory, and cognitive flexibility. Scores on the individual executive function tasks were correlated against frequency of self-reported media-multitasking, but no significant relationships were found. Trait anxiety, however, was found to be significantly associated with greater frequency of self-reported media-multitasking. The present study found no evidence of a relationship between the frequency of self-reported media-multitasking and executive functioning. The possible reasons for this are discussed. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

Individual differences in media multitasking ability: The importance of cognitive flexibility

Abstract: Previous research on media multitasking has often focussed on the frequency with which people perform this type of behaviour. Heavy media multitaskers have been found to differ from light media multitaskers in their performance of tasks involving executive functioning (although these differences have not always been found consistently). The aim of the present study was to explore individuals’ executive functioning in relation to their ability to media multitask (i.e., their ability to recall information presented during the session), rather than their propensity to media multitask. Participants (N= 116, aged 18-25, male N= 32) completed an executive function task battery, inclusive of working memory, inhibition and cognitive flexibility tasks, followed by a studious media multitasking situation. Individual executive function task performance scores were correlated with media multitasking ability scores. Greater cognitive flexibility was significantly associated with greater ability to media multitask, in terms of recall of information from a media multitasking situation. Furthermore, media multitasking had a fatiguing effect on mood, reducing levels of self-reported arousal. Thus, the present study provides some elucidation as to what cognitive characteristics are involved in being able to effectively media multitask, whilst also indicating a possible cognitive mechanism for negative associations found between media multitasking and academic performance.

Media Multitasking and Executive Functioning in Young Adults

Abstract: The purpose of this thesis was to determine the relationships between young adults executive functioning and media multitasking. This was addressed through the systematic exploration of executive functioning utilising behavioural performance tasks, informed by Diamond’s (2013) executive function framework that details three functions; inhibition, working memory and cognitive flexibility, in relation to media multitasking. In fulfilling this aim, an initial investigation was conducted which assessed self-reported frequency of media multitasking (utilising the Media Multitasking Index by Ophir, Nass & Wagner, 2009, including the full continuum of scores) in relation to performance on executive function tasks assessing inhibition, working memory and cognitive flexibility. No association between aspects of young adults executive functioning and self-reported frequency of media multitasking was found. Following this, the thesis continued with the systematic exploration of inhibition, working memory and cognitive flexibility in relation to media multitasking, progressing with the inclusion of a novel assessment of media multitasking ability. Within this second study, media multitasking was explored using objective measures, with participants completing a media multitasking situation. This type of media multitasking assessment has not previously been used in conjunction with performance on a full battery of executive function tasks. The study demonstrated an association between young adults’ cognitive flexibility and their ability to media multitask, in terms of recall of information from a media multitasking situation. It also reflected real world implications of media multitasking in terms of including a novel manipulation of media multitasking within a single device or between multiple devices. Lastly, the final empirical study explored the proximal effects of media multitasking on executive functioning in young adults, for which none were found. In addition to the main aim, a concern of the thesis was to explore the relationship between trait mood and media multitasking. In this regard, self-reported media multitasking was associated with trait anxiety, with higher levels of anxiety associated with more frequent media multitasking in young adults. Other aspects of mood were also assessed throughout the two latter empirical studies, which highlighted a possible fatiguing effect of media engagement (inclusive of media multitasking) on mood. This thesis found no evidence that young adults’ self-reported frequency of media multitasking is associated with their executive functioning. However, there is evidence of the involvement of cognitive flexibility in young adults’ ability to media multitask, when assessing the recall of information from a session of media multitasking. Furthermore, media multitasking between multiple devices is no more detrimental than media multitasking within a single device in terms of the recall of information from a media multitasking situation. Additionally, media engagement (inclusive of media multitasking) does not proximally affect executive function performance although it may fatigue mood.

Streptococcus pneumoniae: transmission, colonization and invasion

Abstract: Streptococcus pneumoniae has a complex relationship with its obligate human host. On the one hand, the pneumococci are highly adapted commensals, and their main reservoir on the mucosal surface of the upper airways of carriers enables transmission. On the other hand, they can cause severe disease when bacterial and host factors allow them to invade essentially sterile sites, such as the middle ear spaces, lungs, bloodstream and meninges. Transmission, colonization and invasion depend on the remarkable ability of S. pneumoniae to evade or take advantage of the host inflammatory and immune responses. The different stages of pneumococcal carriage and disease have been investigated in detail in animal models and, more recently, in experimental human infection. Furthermore, widespread vaccination and the resulting immune pressure have shed light on pneumococcal population dynamics and pathogenesis. Here, we review the mechanistic insights provided by these studies on the multiple and varied interactions of the pneumococcus and its host.

Effects of Cannabis on Neurocognitive Functioning: Recent Advances, Neurodevelopmental Influences, and Sex Differences

Abstract: Decades of research have examined the effects of cannabis on neurocognition. Recent advances in this field provide us with a better understanding of how cannabis use influences neurocognition both acutely (during intoxication) and non-acutely (after acute effects subside). Evidence of problems with episodic memory is one of the most consistent findings reported; however, several other neurocognitive domains appear to be adversely affected by cannabis use under various conditions. There is significant variability in findings across studies, thus a discussion of potential moderators is increasingly relevant. The purpose of this review was to 1) provide an update on research of cannabis’ acute and non-acute effects on neurocognition, with a focus on findings since 2007 and 2) suggest and discuss how neurodevelopmental issues and sex differences may influence cannabis effects on neurocognition. Finally we discuss how future investigations may lead to better understanding of the complex interplay among cannabis, stages of neurodevelopment, and sex on neurocognitive functioning.

Acute and long-term effects of cannabis use: a review.

Abstract: Cannabis remains the most commonly used and trafficked illicit drug in the world. Its use is largely concentrated among young people (15- to 34-year-olds). There is a variety of cannabis use patterns, ranging from experimental use to dependent use. Men are more likely than women to report both early initiation and frequent use of cannabis. Due to the high prevalence of cannabis use, the impact of cannabis on public health may be significant. A range of acute and chronic health problems associated with cannabis use has been identified. Cannabis can frequently have negative effects in its users, which may be amplified by certain demographic and/or psychosocial factors. Acute adverse effects include hyperemesis syndrome, impaired coordination and performance, anxiety, suicidal ideations/tendencies, and psychotic symptoms. Acute cannabis consumption is also associated with an increased risk of motor vehicle crashes, especially fatal collisions. Evidence indicates that frequent and prolonged use of cannabis can be detrimental to both mental and physical health. Chronic effects of cannabis use include mood disorders, exacerbation of psychotic disorders in vulnerable people, cannabis use disorders, withdrawal syndrome, neurocognitive impairments, cardiovascular and respiratory and other diseases.

Inflammation induced by influenza virus impairs human innate immune control of pneumococcus

Abstract: Colonization of the upper respiratory tract by pneumococcus is important both as a determinant of disease and for transmission into the population. The immunological mechanisms that contain pneumococcus during colonization are well studied in mice but remain unclear in humans. Loss of this control of pneumococcus following infection with influenza virus is associated with secondary bacterial pneumonia. We used a human challenge model with type 6B pneumococcus to show that acquisition of pneumococcus induced early degranulation of resident neutrophils and recruitment of monocytes to the nose. Monocyte function was associated with the clearance of pneumococcus. Prior nasal infection with live attenuated influenza virus induced inflammation, impaired innate immune function and altered genome-wide nasal gene responses to the carriage of pneumococcus. Levels of the cytokine CXCL10, promoted by viral infection, at the time pneumococcus was encountered were positively associated with bacterial load.