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Risk factors for cognitive decline in older people with type 2 diabetes
Full text linkPeople with type 2 diabetes are at increased risk of age-related cognitive impairment.
Previous literature has focused on case-control studies comparing rates of cognitive
impairment in patients with and without diabetes. Investigations of potential risk
factors for cognitive impairment (including those with increased prevalence in
diabetes, such as macrovascular disease, and diabetes-specific factors such as
hypoglycaemia) in study populations consisting exclusively of patients with type 2
diabetes have been largely neglected. Moreover, previous studies have failed to take
advantage of the extensive characterisation and prospective nature of longitudinal
cohort studies to investigate the relative predictive ability of a wider range of
potential risk factors for cognitive decline. Using data from the prospective
Edinburgh Type 2 Diabetes Study (ET2DS) the present thesis aimed (i) to determine
associations of cognitive decline with macrovascular disease and with severe
hypoglycaemia, and (ii) to compare a wider range of potential risk factors in their
ability to predict cognitive decline.
In 2006/2007, 1066 patients with type 2 diabetes (aged 60 to 75 years) attended the
baseline ET2DS clinic and 831 returned for the follow-up at year 4. Subjects were
extensively characterised for risk factor profiles at baseline, and at year 4 for
incidence of severe hypoglycaemia. Socioeconomic status was estimated using
postcode data. Scores on seven tests of age-sensitive ‘fluid’ cognitive function,
which were administered at baseline and at year 4, were used to derive a general
cognitive component (‘g’). A vocabulary-based test, administered at baseline,
estimated pre-morbid ability. Findings are reported in three parts. 1.) Macrovascular
disease and cognition: Subjects with higher levels of biomarkers indicative of
subclinical macrovascular disease, including plasma N-terminal pro-brain natriuretic
peptide and carotid intima-media thickness, had significantly steeper four-year
cognitive decline, independent of traditional cardiovascular risk factors, stroke,
socioeconomic status and estimated pre-morbid cognitive ability. For ankle-brachial
pressure index, the association fell just short of statistical significance. Effect sizes
were overall modest, with fully adjusted standardised beta coefficients ranging from
0.06 to -0.12. Little evidence was found for associations of the symptomatic markers
of macrovascular disease with four-year change in cognitive function that was independent of participants’ pre-morbid ability and socioeconomic status. 2.) Severe
hypoglycaemia and cognition: Subjects with lower cognitive ability at baseline were
at two-fold increased risk of experiencing their first-ever incident severe
hypoglycaemia during follow-up. The rate of four-year cognitive decline was
significantly steeper in those exposed to hypoglycaemia compared with
hypoglycaemia-free participants, independently of cardiovascular risk factors, microand
macrovascular disease and of estimated pre-morbid cognitive ability. Effect sizes
again were overall modest (Cohen’s d = 0.2 to 0.3 for statistically significant
differences in four-year cognitive decline between subjects with and those without
hypoglycaemia, following multivariable adjustment) 3.) Consideration of a wider
range of risk factors and cognition: A stepwise linear regression model including a
total of 15 metabolic and vascular risk factors identified inflammation, smoking and
poorer glycaemic control (in addition to some of the subclinical markers of
macrovascular disease) as predictive of a steeper four-year cognitive decline. Other
traditional cardiovascular risk factors, diabetic retinopathy, clinical macrovascular
disease and a baseline history of severe hypoglycaemia were not included in this
model. The interpretation of the latter finding is limited, however, by the fact that the
stepwise regression procedure may exclude true predictors from a model when they
correlate with already included risk factors.
This thesis has demonstrated associations of later-life cognitive decline in people
with type 2 diabetes with markers of subclinical macrovascular disease and poor
glycaemic control (including hypoglycaemia) as well as other cardiometabolic risk
factors (inflammation, smoking). Findings suggest that associations are relatively
weak and complex due to inter-relationships amongst risk factors, and indicate a role
of pre-morbid ability and socioeconomic status (which as risk factors are difficult to
modify) in the relationships of risk factors with cognitive decline. Future research
including case-control studies to compare risk factor associations between people
with type 2 diabetes and non-diabetic older adults and randomised controlled trials to
evaluate potential causal effects of individual modifiable risk factors on cognitive
decline, will help to evaluate the mechanisms underlying the observation that people
with type 2 diabetes are at risk of cognitive impairment in later life
Metabolische Risikofaktoren für kognitive Dysfunktion im perioperativen Verlauf
Full text linkPostoperative cognitive dysfunction (POCD) is characterized by a cognitive decline from pre- to post-surgery assessment, but is underresearched from an epidemiological perspective. Previous studies have identified metabolic dysfunction as a risk factor for age-related cognitive impairment (ACI) which too is characterized by cognitive deficits but occurs in the general population during ageing. Thus, metabolic dysfunction is a strong candidate risk factor for POCD. Here, I used a total of 4 surgical cohort studies of middle-aged to older adults with extensive anthropometric, clinical (and in part molecular) phenotyping as well as detailed pre- and post-surgical cognitive assessment to test the hypothesis that ACI and POCD share metabolic risk factors. I found partial evidence for in favor of this hypothesis. The implications of this work are three-fold: i) the findings suggest that ACI and POCD may (in part) be driven by similar pathophysiological mechanisms. ii) by measuring metabolic function before surgery, we may be able to risk stratify older surgical patients and – in elective surgery settings – empower at-risk patients for informed decision making. ii) if future work determines that the associations found here reflect causal relationships of metabolic dysfunction with ACI and POCD, we could set up preventive measures. Ultimately, the epidemiological analyses presented here provide one step towards a better understanding of ACI and POCD
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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