Inconsistency in serial choice decision and motor reaction times dissociate in younger and older adults

Intraindividual variability (inconsistency) in reaction time (RT) latencies was investigated in a group of younger (M = 25.46 years) and older (M = 69.29 years) men. Both groups performed 300 trials in 2-, 4-, and 8-choice RT conditions where RTs for decision and motor components of the task were recorded separately. A dissociation was evident in that inconsistency was greater in older adults for decision RTs when task demands relating to the number of choices and fatigue arising from time-on-task were high. For younger persons, a weak trend toward greater inconsistency in motor RTs was evident. The results are consistent with accounts suggesting that inconsistency in neurobiological mechanisms increases with age, and that attentional lapses or fluctuations in executive control contribute to RT inconsistency

Intraindividual Variability in Reaction Time Predicts Cognitive Outcomes 5 Years Later

Objective: Building on results suggesting that intraindividual variability in reaction time (inconsistency) is highly sensitive to even subtle changes in cognitive ability, this study addressed the capacity of inconsistency to predict change in cognitiv

Poorer mental health is associated with cognitive deficits in old age

Few studies have examined the association between within-person (WP) reaction time (RT) variability and mental health (depression, anxiety, and social dysphoria) in old age. Therefore, we investigated mental health (using the General Health Questionnaire) and cognitive function (mean RT or WP variability) in 257 healthy, community-dwelling adults aged 50-90 years (M = 63.60). The cognitive domains assessed were psychomotor performance, executive function, visual search, and recognition. Structural equation models revealed that for WP variability, but not mean RT, poorer mental health was associated with visual search and immediate recognition deficits in older persons and that these relationships were partially mediated by executive function. The dissociation between mean RT and WP variability provides evidence that the latter measure may be particularly sensitive to the subtle effects of mental health on cognitive function in old age

Intra-Individual Variability in Alzheimer's Disease and Cognitive Aging: Definitions, Context, and Effect Sizes

To explore different definitions of intra-individual variability (IIV) to summarize performance on commonly utilized cognitive tests (Mini Mental State Exam; Clock Drawing Test); compare them and their potential to differentiate clinically-defined populations; and to examine their utility in predicting clinical change in individuals from the Alzheimer's Disease Neuroimaging Initiative (ADNI).) were computed for each of these definitions in 500 simulated replicates using scores on the Mini Mental State Exam and Clock Drawing Test. IIV was computed based on test items separately (‘within test’ IIV) and the two tests together (‘across test’ IIV). The best performing definition was then used to compute IIV for a third test, the Alzheimer's Disease Assessment Scale-Cognitive, and the simulations and effect sizes were again computed. All effect size estimates based on simulated data were compared to those computed based on the total scores in the observed data. Association between total score and IIV summaries of the tests and the Clinician's Dementia Rating were estimated to test the utility of IIV in predicting clinically meaningful changes in the cohorts over 12- and 24-month intervals.ES estimates differed substantially depending on the definition of IIV and the test(s) on which IIV was based. IIV (coefficient of variation) summaries of MMSE and Clock-Drawing performed similarly to their total scores, the ADAS total performed better than its IIV summary.IIV can be computed within (items) or across (totals) items on commonly-utilized cognitive tests, and may provide a useful additional summary measure of neuropsychological test performance

The impact of beliefs about face recognition ability on memory retrieval processes in young and older adults

This study examined whether beliefs about face recognition ability differentially influence memory retrieval in older compared to young adults. Participants evaluated their ability to recognise faces and were also given information about their ability to perceive and recognise faces. The information was ostensibly based on an objective measure of their ability, but in actuality, participants had been randomly assigned the information they received (high ability, low ability or no information control). Following this information, face recognition accuracy for a set of previously studied faces was measured using a remember– know memory paradigm. Older adults rated their ability to recognise faces as poorer compared to young adults. Additionally, negative information about face recognition ability improved only older adults’ ability to recognise a previously seen face. Older adults were also found to engage in more familiarity than item-specific processing than young adults, but information about their face recognition ability did not affect face processing style. The role that older adults’ memory beliefs have in the meta-cognitive strategies they employ is discussed

Protocol for Fit Bodies, Fine Minds: a randomized controlled trial on the affect of exercise and cognitive training on cognitive functioning in older adults

Background. Declines in cognitive functioning are a normal part of aging that can affect daily functioning and quality of life. This study will examine the impact of an exercise training program, and a combined exercise and cognitive training program, on the cognitive and physical functioning of older adults. Methods/Design. Fit Bodies, Fine Minds is a randomized, controlled trial. Community-dwelling adults, aged between 65 and 75 years, are randomly allocated to one of three groups for 16 weeks. The exercise-only group do three 60-minute exercise sessions per week. The exercise and cognitive training group do two 60-minute exercise sessions and one 60-minute cognitive training session per week. A no-training control group is contacted every 4 weeks. Measures of cognitive functioning, physical fitness and psychological well-being are taken at baseline (0 weeks), post-test (16 weeks) and 6-month follop (40 weeks). Qualitative responses to the program are taken at post-test. Discussion. With an increasingly aged population, interventions to improve the functioning and quality of life of older adults are particularly important. Exercise training, either alone or in combination with cognitive training, may be an effective means of optimizing cognitive functioning in older adults. This study will add to the growing evidence base on the effectiveness of these interventions. Trial Registration. Australian Clinical Trials Register: ACTRN012607000151437

Enhanced diagnostic immunofluorescence using biopsies transported in saline

BACKGROUND: The demonstration of tissue-bound immunoreactants by direct immunofluorescence microscopy (DIF) is a valuable parameter in the diagnosis of various autoimmune and immunecomplex-mediated skin diseases. For preservation of tissue-bound immunoreactants, biopsies are usually fresh-frozen in liquid nitrogen or transported in Michel's fixative. But even optimally preserved tissue specimens are no guarantee for the correct diagnosis by DIF, especially when weak to moderate IgG fluorescence of the epidermal basement membrane zone is involved. In such cases false negative results are easily obtained due to the relatively high dermal "background" fluorescence produced by polyclonal anti-human IgG fluorescein conjugates. METHODS: In the present study we have compared the use of normal saline (0.9% NaCl) with liquid nitrogen and Michel's fixative as transport medium for skin biopsies. From 25 patients with an autoimmune skin disease (pemphigus, pemphigoid, lupus erythematosus and vasculitis) four matched skin biopsies were obtained and transported in either saline for 24 and 48 hours, liquid nitrogen, or Michel's fixative for 48 hours. RESULTS: Direct IF microscopy showed significant reduction of background fluorescence (p < 0.01) and relatively enhanced desired specific (IgG, IgA) staining in biopsies transported in saline. A conclusive or tentative IF diagnosis was reached in 92% after 24 h saline, 83% after 48 h saline, 68% after freezing in liquid nitrogen, and 62% after 48 h Michel's medium (n = 25). CONCLUSIONS: We conclude that transporting biopsies without freezing in normal saline for 24 hours is an adequate and attractive method for routine IF diagnosis in autoimmune and immune complex-mediated dermatoses. The superior results with saline incubation are explained by washing away of IgG background in dermis and epidermis