0000000000652437
AUTHOR
Edgar Chan
showing 11 related works from this author
Do aetiology, age and cogntive reserve affect executive performance?
2017
Background: The behavioral effect of frontal lesions may be influenced by confounding factors such as aetiology, age and cogntive reserve. Yet no studies have investigated their effects on patients with focal lesions. Objective: Is the grouping of patients with frontal lesions caused by stroke or tumours methodologically appropriate; does age affect cognitive performance, can cognitive reserve protect against cognitive impairment? Patients and Methods/Material and Methods: Cognitive performance was compared across a large sample of frontal patients with stroke, high or low grade tumour, or meningioma. The effect of age, education and NART IQ on the cognitive performance of patients with foc…
Underestimation of cognitive impairments by the Montreal Cognitive Assessment (MoCA) in an acute stroke unit population
2013
Abstract Background and purpose The Montreal Cognitive Assessment (MoCA) is an increasingly popular clinical screening tool for detecting cognitive impairment in stroke, but few studies have directly compared performance on the MoCA with neuropsychological assessment. Our retrospective study examined the extent to which intact performance on the MoCA reflects intact cognition as determined by neuropsychological assessment. Methods In this retrospective study, cognitive profiles for 136 acute stroke patients admitted to the Acute Stroke Unit who had available MoCA and neuropsychological assessment data were examined. Results 22% of our patients were deemed cognitively intact on the MoCA. Of …
The test accuracy of the Montreal Cognitive Assessment (MoCA) by stroke lateralisation
2017
Abstract Background The Montreal Cognitive Assessment (MoCA) is an increasingly popular screening tool for detecting cognitive impairment post-stroke. However its' test accuracy by stroke lateralisation is as yet unknown. Aim Our aim was to investigate whether the test accuracy of the MoCA differs by stroke lateralisation across different cognitive domains. Methods We retrospectively examined the cognitive profiles of 228 subacute stroke patients (86 Left, 142 Right), comparing MoCA-total and domain-specific scores with performance on detailed neuropsychological assessment. Results The prevalence of cognitive impairment detected on neuropsychological assessment was high and relatively compa…
Fluency and rule breaking behaviour in the frontal cortex
2020
Design (DF) and phonemic fluency tests (FAS; D-KEFS, 2001) are commonly used to investigate voluntary generation. Despite this, several important issues remain poorly investigated. In a sizeable sample of patients with focal left or right frontal lesion we established that voluntary generation performance cannot be accounted for by fluid intelligence. For DF we found patients performed significantly worse than healthy controls (HC) only on the switch condition. However, no significant difference between left and right frontal patients was found. In contrast, left frontal patients were significantly impaired when compared with HC and right frontal patients on FAS. These lateralization findin…
Cognitive estimation: Performance of patients with focal frontal and posterior lesions
2018
The Cognitive Estimation Test (CET) is a widely used test to investigate estimation abilities requiring complex processes such as reasoning, the development and application of appropriate strategies, response plausibility checking as well as general knowledge and numeracy (e.g., Shallice and Evans, 1978; MacPherson et al., 2014). Thus far, it remains unknown whether the CET is both sensitive and specific to frontal lobe dysfunction. Neuroimaging techniques may not represent a useful methodology for answering this question since the complex processes involved are likely to be associated with a large network of brain regions, some of which are not functionally necessary to successfully carry …
Limitations of the trail making test part-B in assessing frontal executive dysfunction.
2015
AbstractPart B of the Trail Making Test (TMT-B) is one of the most widely used neuropsychological tests of “executive” function. A commonly held assumption is that the TMT-B can be used to detect frontal executive dysfunction. However, so far, research evidence has been limited and somewhat inconclusive. In this retrospective study, performance on the TMT-B of 55 patients with known focal frontal lesions, 27 patients with focal non-frontal lesions and 70 healthy controls was compared. Completion time and the number of errors made were examined. Patients with frontal and non-frontal lesions performed significantly worse than healthy controls for both completion time and the number of errors.…
Inhibition processes are dissociable and lateralized in human prefrontal cortex
2016
The prefrontal cortex (PFC) is known to make fundamental contributions to executive functions. However, the precise nature of these contributions is incompletely understood. We focused on a specific executive function, inhibition, the ability to suppress a pre-potent response. Functional imaging and animal studies have studied inhibition. However, there are only few lesion studies, typically reporting discrepant findings. For the first time, we conducted cognitive and neuroimaging investigations on patients with focal unilateral PFC lesions across two widely used inhibitory tasks requiring a verbal response: The Hayling Part 2 and Stroop Colour-Word Tests. We systematically explored the rel…
Cognitive Reserve Proxies Do Not Differentially Account for Cognitive Performance in Patients with Focal Frontal and Non-Frontal Lesions
2020
AbstractObjective:Cognitive reserve (CR) suggests that premorbid efficacy, aptitude, and flexibility of cognitive processing can aid the brain’s ability to cope with change or damage. Our previous work has shown that age and literacy attainment predict the cognitive performance of frontal patients on frontal-executive tests. However, it remains unknown whether CR also predicts the cognitive performance of non-frontal patients.Method:We investigated the independent effect of a CR proxy, National Adult Reading Test (NART) IQ, as well as age and lesion group (frontal vs. non-frontal) on measures of executive function, intelligence, processing speed, and naming in 166 patients with focal, unila…
Domain-specific characterisation of early cognitive impairment following spontaneous intracerebral haemorrhage.
2018
Cognitive deficits after spontaneous intracerebral haemorrhage (ICH) are common and result in functional impairment, but few studies have examined deficits across cognitive domains in the subacute phase. This study aims to describe the cognitive profile following acute ICH and explore how cerebral amyloid angiopathy (CAA) may impact performance. We retrospectively reviewed 187 consecutive patients with ICH (mean age 58.9 years, 55.6% male) with available imaging and neuropsychological data (median 12 days after stroke). In our cohort, 84% (n = 158) were impaired in at least one cognitive domain and 65% (n = 122) in two or more domains. Deficits in non-verbal IQ (76.6%), information processi…
The impact of different aetiologies on the cognitive performance of frontal patients
2014
Neuropsychological group study methodology is considered one of the primary methods to further understanding of the organisation of frontal ‘executive’ functions. Typically, patients with frontal lesions caused by stroke or tumours have been grouped together to obtain sufficient power. However, it has been debated whether it is methodologically appropriate to group together patients with neurological lesions of different aetiologies. Despite this debate, very few studies have directly compared the performance of patients with different neurological aetiologies on neuropsychological measures. The few that did included patients with both anterior and posterior lesions. We present the first co…
The effect of age on cognitive performance of frontal patients
2015
Age is known to affect prefrontal brain structure and executive functioning in healthy older adults, patients with neurodegenerative conditions and TBI. Yet, no studies appear to have systematically investigated the effect of age on cognitive performance in patients with focal lesions. We investigated the effect of age on the cognitive performance of a large sample of tumour and stroke patients with focal unilateral, frontal (n=68), or non-frontal lesions (n=45) and healthy controls (n=52). We retrospectively reviewed their cross sectional cognitive and imaging data. In our frontal patients, age significantly predicted the magnitude of their impairment on two executive tests (Raven's Advanc…