Age Differences in Intra-Individual Variability in Simple and Choice Reaction Time: Systematic Review and Meta-Analysis

Intra-individual variability in reaction time (RT IIV) is considered to be an index of central nervous system functioning. Such variability is elevated in neurodegenerative diseases or following traumatic brain injury. It has also been suggested to increase with age in healthy ageing.To investigate and quantify age differences in RT IIV in healthy ageing; to examine the effect of different tasks and procedures; to compare raw and mean-adjusted measures of RT IIV.Four electronic databases: PsycINFO, Medline, Web of Science and EMBASE, and hand searching of reference lists of relevant studies.English language journal articles, books or book chapters, containing quantitative empirical data on simple and/or choice RT IIV. Samples had to include younger (under 60 years) and older (60 years and above) human adults.Studies were evaluated in terms of sample representativeness and data treatment. Relevant data were extracted, using a specially-designed form, from the published report or obtained directly from the study authors. Age-group differences in raw and RT-mean-adjusted measures of simple and choice RT IIV were quantified using random effects meta-analyses.Older adults (60+ years) had greater RT IIV than younger (20-39) and middle-aged (40-59) adults. Age effects were larger in choice RT tasks than in simple RT tasks. For all measures of RT IIV, effect sizes were larger for the comparisons between older and younger adults than between older and middle-aged adults, indicating that the age-related increases in RT IIV are not limited to old age. Effect sizes were also larger for raw than for RT-mean-adjusted RT IIV measures.RT IIV is greater among older adults. Some (but not all) of the age-related increases in RT IIV are accounted for by the increased RT means

Next steps after diagnosing dementia: interventions to help patients and families

The way that a diagnosis of dementia is delivered to patients, what information is provided and what practical advice and support is arranged has a lasting impact and deserves at least as much attention as the process of assessment and investigation. Individuals and their families require an honest yet sensitive discussion about the nature and cause of their problems, using non-technical language and tailored to their priorities and needs. This should lead on to the provision of good-quality information in an accessible format. Priorities for intervention include medication review, attention to sensory deficits, appropriate pharmacological and nonpharmacological treatment, best use of memory aids and strategies and discussion of driving eligibility, financial entitlement and legal advice. Referral onwards should be made to an appropriate individual or service to provide ongoing emotional and practical support and signposting

Subcortical ischaemic vascular cognitive impairment: insights from reaction measures

In this study, reaction time (RT), intraindividual variability (IIV), and errors, and the effects of practice and processing load upon such function, were compared in patients with subcortical ischemic vascular cognitive impairment (SIVCI) [n = 27] and cognitively healthy older adults (CH) [n = 26]. Compared to CH aging, SIVCI was characterized by a profile of significantly slowed RT, raised IIV, and higher error levels, particularly in the presence of distracting stimuli, indicating that the integrity and/or accessibility of the additional functions required to support high processing load, serial search strategies, are reduced in SIVCI. Furthermore, although practice speeded RT in SIVCI, unlike CH, practice did not lead to an improvement in IIV. This indicates that improvement in RT in SIVCI can in fact mask an abnormally high degree of IIV. Because IIV appears more related to disease, function, and health than RT, its status and potential for change may represent a particularly meaningful, and relevant, disease characteristic of SIVCI. Finally, a high level of within-group variation in the above measures was another characteristic of SIVCI, with such processing heterogeneity in patients with ostensibly the same diagnosis, possibly related to individual variation in pathological load. Detailed measurement of RT, IIV, errors, and practice effects therefore reveal a degree of functional impairment in brain processing not apparent by measuring RT in isolation

The role of biomarkers and imaging in the clinical diagnosis of dementia

Recognition of dementia relies on a good clinical history, supported by formal cognitive testing, but identifying the subtype of dementia may be wrong in 20% or more of cases. Accuracy may be improved by use of imaging and cerebrospinal fluid (CSF) biomarkers. Structural neuroimaging is recommended for most patients, not just to identify potentially reversible surgical pathology, but also to detect vascular changes and patterns of cerebral atrophy. Functional imaging can help to confirm neurodegeneration and to distinguish dementia subtypes when structural imaging has been inconclusive. Amyloid-positron emission tomography scans reflect neuritic plaque burden and identify the earliest pathological changes in Alzheimer’s disease, but their value outside research settings is still uncertain. A combination of low CSF amyloid β1–42 and high CSF total-tau or phospho-tau also has high predictive power for AD pathology, but diagnostic usefulness decreases with age because of the increased prevalence of AD-type pathology in non-demented people. The need to use biomarkers more routinely will become necessary as disease-modifying treatments become available and accurate subtype diagnosis will be required at an early (ideally pre-dementia) stage. Clinicians should be considering the resources and expertise that will soon be needed for optimal dementia diagnosis

Segmentation of clock drawings based on spatial and temporal features

The Clock Drawing Test (CDT) is an inexpensive and effective measure for early detection of cognitive impairment in the elderly, which is important for timely diagnosis and initiation of appropriate treatment. Currently, medical experts assess the drawings based on their judgement and a number of available scoring systems. An automatic system for assessment of CDT drawings would simultaneously decrease the waiting time for a specialist appointment and improve accessibility of the test to the patients. Published research has only started to address the problem of automatic assessment of CDT drawings and existing systems require user intervention during the segmentation of the CDT drawing into its composing parts, such as numbers and clock hands. In this paper, a new set of temporal and spatial features automatically extracted from the CDT data acquired using a graphics tablet is proposed. Consequently, a Support Vector Machine (SVM) classifier is employed to segment the CDT drawings into their elements, such as numbers and clock hands, on the basis of the extracted features. The proposed algorithm is tested on two data sets, the first set consisting of 65 drawings made by healthy people, and the second consisting of 100 drawings reproduced from actual drawings of dementia patients. The test on both data sets shows that the proposed method outperforms the current state-of-the-art method for CDT drawing segmentation