Biomedical subjects

Joseph A Sergeant

Publications and source records attributed to Joseph A Sergeant.

9 recordsLinked to original sources

PubMed2003

The top and the bottom of ADHD: a neuropsychological perspective.

Five models of attention deficit/hyperactivity disorder (ADHD) are reviewed. It is proposed that the cognitive-energetic model provides a reasonably comprehensive account of ADHD by incorporating the features of both the inhibition and delay aversion models. It is suggested that ADHD can only be accounted for by an analysis at three levels: top-down control, specific cognitive processes and energetic factors. It is argued that a refined and conceptually comprehensive neuropsychological battery is needed to advance research in ADHD. A widely distributed neural network involving frontal, basal ganglia, limbic and cerebellar loci seem implicated in ADHD.

Attention Deficit Disorder with Hyperactivity↗

PubMed2003

Hemispheric differences in stop task performance.

This study examined hemispheric specialization for stop task performance. It was found that inhibitory performance was better for stop signals presented in the right visual field. This result provided support for the hypothesis that, during stop task performance, subjects call upon the left-lateralized neural system that is involved in active attention. It was suggested that a stop task requires such a mode of attention because subjects maintain a tonic readiness for inhibitory action while being engaged in the stop task's go routine. Subjects are continuously alert for possible stop signals while discriminating between go stimuli. The stop task may be considered a typical activation task.

Adolescent↗

PubMed2003

Pain processing in dementia and its relation to neuropathology.

Most clinical studies of pain in dementia have focused on assessment procedures that are sensitive to pain in "demented" or "cognitively impaired" elderly patients. The neuropathology of dementia has not played a major part in pain assessment. In this review, the neuropathological effects of dementia on the medial and the lateral pain systems are discussed. We focus on Alzheimer's disease (AD), vascular dementia, and frontotemporal dementia. Lewy-body disease and Creutzfeldt-Jakob disease are briefly reviewed. The results of the studies reviewed show that, although the subtypes of dementia show common neuropathological features (such as atrophy and white-matter lesions), the degree by which they occur and affect pain-related areas determine the pattern of changes in pain experience. More specifically, in AD and even more so in frontotemporal dementia, a decrease in the motivational and affective components of pain is generally present whereas vascular dementia might be characterised by an increase in affective pain experience. Future studies should combine data from experimental pain studies and neuropathological information for pain assessment in dementia.

Animals↗

PubMed2003

The effect of methylphenidate on three forms of response inhibition in boys with AD/HD.

The current study was aimed at (a) investigating the effect of three doses methylphenidate (MPH) and placebo on inhibition of a prepotent response, inhibition of an ongoing response, and interference control in Attention Deficit/Hyperactivity Disorder (AD/HD), and (b) studying dose-response relations for the three forms of response inhibition. To meet these aims, the following tasks were selected: two versions of the Stop Paradigm for inhibition of a prepotent response, a Circle Tracing Task and a recently developed Follow Task for inhibition of an ongoing response, and the Stroop Color-Word Test and an Eriksen Flanker Task for interference control. These tasks were administered to 23 boys with AD/HD during four treatment conditions: 5 mg MPH, 10 mg MPH, 20 mg MPH, and placebo. A pseudorandomized, multiple-blind, placebo-controlled, within-subject design was used. As hypothesized, inhibitory control in children with AD/HD improved under MPH compared to placebo. However, this effect was only significant for inhibition of a prepotent response and inhibition of an ongoing response (as measured by the Follow Task), but not for interference control. The relation between treatment condition and response was linear. However, this linear relation was due to improved inhibitory control under MPH compared to placebo, because no effects of MPH dose were observed for any of the response inhibition measures.

Attention↗

PubMed2003

Non-pharmacological interventions in cognitively impaired and demented patients--a comparison with cholinesterase inhibitors.

The present paper reviews studies examining the effects of non-pharmacological stimulation, i.e. bright light, physical activity and tactile stimulation (touch), on cognition, affective behaviour, and the sleep-wake rhythm of impaired and demented elderly, both in a qualitative (narrative) and quantitative (meta-analytic) manner. An extensive search through eight bibliographic data bases (PubMed, Web of Science, ERIC, PsychINFO, Psyndex, Cinahl, Biological Abstracts and Rehabdata) was performed up to August 2002. The primary criterion for inclusion in this review was that studies provided sufficient data to calculate effect-sizes. In the qualitative analysis, all three types of stimulation appeared to improve cognitive functioning. Disturbances in behaviour react positively to bright light and tactile stimulation. Bright light was also beneficial to sleep. Tactile stimulation had, moreover, a beneficial influence on the patient-caretaker relationship. A comparison was made with several representative papers published since 1991 on the effects of acetylcholinesterase inhibitors on cognition and behaviour with representative papers on non-pharmacological stimulation interventions. Data indicated that improvements in cognition and affective behaviour by non-pharmacological interventions (d' = 0.32) and by cholinesterase inhibitors (d' = 0.31) were of similar effect-size. Possible mechanisms underlying the non-pharmacological stimulation effects are discussed and suggestions offered for future research.

Affect↗

PubMed2003

Pain assessment in patients with possible vascular dementia.

PREVIOUS studies comparing Alzheimer's disease (AD) patients with the normal elderly suggest that AD patients experience less pain. In the present study, pain reporting in 20 patients with possible vascular dementia (VaD) was compared to 20 nondemented elderly who had comparable pain conditions. It was hypothesized that, due to de-afferentiation, the possible VaD patients would experience more pain than the cognitively intact elderly. Pain assessment was conducted using three visual analogue scales, (1) the Coloured Analogue Scale (CAS) for Pain Intensity, (2) the CAS for Pain Affect, and (3) the Faces Pain Scale (FPS); a verbal pain questionnaire, Number of Words Chosen--Affective (NWC-A) of the McGill Pain Questionnaire; and an observation scale, the Checklist of Nonverbal Pain Indicators (CNPI). Results showed a significant increase in the scores on the CAS for Pain Affect and the FPS in the demented patients compared to the control group. There was a tendency for an increase in scores on the CNPI in the VaD group. These results suggest that patients with possible VaD suffer more pain than healthy elderly without cognitive impairment.

Aged↗

PubMed2002

How specific is a deficit of executive functioning for attention-deficit/hyperactivity disorder?

A selective review of research in the executive functioning (EF) is given for attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), conduct disorder (CD), higher functioning autism (HFA) and Tourette syndrome. The review is restricted due to changes in the classification of the disorder in recent years and secondly the heterogeneity of EF is restricted to five key areas of concern, inhibition, set shifting, working memory, planning, and fluency. The review makes clear that there are strong differences between child psychopathological groups and controls on these EFs. However, future research will be needed to identify an EF deficit or profile, which is specific for these disorders.

Adolescent↗

PubMed2002

Fronto-central dysfunctions in reading disability depend on subtype: guessers but not spellers.

The goal of this study was to test the hypothesis that the inhibitory deficits previously found in children with the guessing subtype of dyslexia (who read fast and inaccurately) can be attributed to dysfunctions in the fronto-central brain areas. For this purpose, the electrocortical correlates of the inhibition mechanism were assessed in a stop task that was adapted for event-related brain potential recording. It was found that in children with the spelling subtype of dyslexia (who read slowly and accurately) and normal readers, a positive component with a fronto-central scalp distribution was related to processes engaged in the inhibition of a response. Guessers did not show this "inhibition P300." Analyses of the lateralized readiness potential (LRP) data suggested that response inhibition in spellers depended (at least in part) on their ability to inhibit the central activation of the response. In guessers, the association between response inhibition and inhibition of activity in the central motor structures was found to be weaker. It was concluded that the inhibitory deficits in guessers can be attributed to dysfunctions in the fronto-central brain structures involved in selective motor inhibition (indicated by the LRP data) and nonselective motor inhibition (indicated by the P300 data). It was suggested that there may be an association between guessers and attention deficit hyperactivity disorder children in that both clinical groups may suffer from the same type of deficits in executive functioning.

Analysis of Variance↗

PubMed2002

Effects of transcutaneous electrical nerve stimulation (TENS) on non-pain related cognitive and behavioural functioning.

An extensive search through nine electronic bibliographic databases (PubMed, Cochrane Library, Web of Science, ERIC, PsychINFO, Psyndex, Cinahl, Biological Abstracts, Rehabdata) was performed in order to review the effects of Transcutaneous Electrical Nerve Stimulation (TENS) on non-pain related cognitive and behavioural functioning. Eight studies were identified on neglect due to stroke, six studies on Alzheimer's disease (AD), one study on aging, and two studies on coma due to traumatic brain injury. The results of the various studies revealed that TENS has a variety of effects. These consist of enhancement of somatosensory functioning, visuo-spatial abilities and postural control in neglect, improved memory, affective behaviour and rest-activity rhythm in AD and acceleration of awakening in coma. Effectiveness of TENS is discussed in relation to various stimulation parameters: duration, frequency, pulse width and intensity. It is argued that arousal may underlie the beneficial influence of TENS in various conditions. Finally, suggestions are offered for future research.

Adolescent↗