Abstract Introduction Although preclinical dementia is characterized by decline in cognition and daily functioning, little is known on their temporal sequence. We investigated trajectories of ...cognition and daily functioning in preclinical dementia, during 18 years of follow-up. Methods In 856 dementia cases and 1712 controls, we repetitively assessed cognition and daily functioning with memory complaints, mini-mental state examination (MMSE), instrumental activities of daily living (IADL), and basic activities of daily living (BADL). Results Dementia cases first reported memory complaints 16 years before diagnosis, followed by decline in MMSE, IADL, and finally BADL. Vascular dementia related to earlier decline in daily functioning but later in cognition, compared with Alzheimer's disease. Higher education related to larger preclinical cognitive decline, whereas apolipoprotein E ( APOE ) ε4 carriers declined less in daily functioning. Discussion These results emphasize the long hierarchical preclinical trajectory of functional decline in dementia. Furthermore, they show that various pathologic, environmental, and genetic factors may influence these trajectories of decline.
Cognitive impairment is an important hallmark of dementia, but deterioration of cognition also occurs frequently in non-demented elderly individuals. In more than 3,000 non-demented persons, aged ...45-99 years, from the population-based Rotterdam Study we studied crosssectional age effects on cognitive function across various domains. All participants underwent an extensive cognitive test battery that tapped into processing speed, executive function, verbal fluency, verbal recall and recognition, visuospatial ability and fine motor skills. General cognitive function was assessed by the g-factor, which was derived from principal component analysis and captured 49.2% of all variance in cognition. We found strongest associations for age with g-factor difference in z-score —0.59 per 10 years; 95% confidence interval (CI) -0.62 to -0.56, fine motor skill (-0.53 per 10 years; 95% CI -0.56 to -0.50), processing speed (-0.49 per 10 years; 95% CI —0.51 to —0.46), and visuospatial ability (—0.48 per 10 years; 95% CI -0.51 to -0.45). In contrast, the effect size for the association between age and immediate recall was only -0.25 per 10 years (95% CI -0.28 to -0.22), which was significantly smaller than the relation between age and fine motor skill (P < 0.001). In conclusion, in nondemented persons of 45 years and older, general cognition deteriorates with aging. More specifically, fine motor skill, processing speed and visuospatial ability, but not memory, are affected most by age.
Previous studies on sensorimotor adaptation revealed no awareness of the nature of the perturbation after adaptation to an abrupt 30° rotation of visual feedback or after adaptation to gradually ...introduced perturbations. Whether the degree of awareness depends on the magnitude of the perturbation, though, has as yet not been tested. Instead of using questionnaires, as was often done in previous work, the present study used a process dissociation procedure to measure awareness and unawareness. A naïve, implicit group and a group of subjects using explicit strategies adapted to 20°, 40° and 60° cursor rotations in different adaptation blocks that were each followed by determination of awareness and unawareness indices. The awareness index differed between groups and increased from 20° to 60° adaptation. In contrast, there was no group difference for the unawareness index, but it also depended on the size of the rotation. Early adaptation varied between groups and correlated with awareness: The more awareness a participant had developed the more the person adapted in the beginning of the adaptation block. In addition, there was a significant group difference for savings but it did not correlate with awareness. Our findings suggest that awareness depends on perturbation size and that aware and strategic processes are differentially involved during adaptation and savings. Moreover, the use of the process dissociation procedure opens the opportunity to determine awareness and unawareness indices in future sensorimotor adaptation research.
To investigate the influence of the amount of cervical movement on the cervico-ocular reflex (COR) and vestibulo-ocular reflex (VOR) in healthy individuals. Eye stabilization reflexes, especially the ...COR, are changed in neck pain patients. In healthy humans, the strength of the VOR and the COR are inversely related. In a cross-over trial the amplitude of the COR and VOR (measured with a rotational chair with eye tracking device) and the active cervical range of motion (CROM) was measured in 20 healthy participants (mean age 24.7). The parameters were tested before and after two different interventions (hyperkinesia: 20 min of extensive active neck movement; and hypokinesia: 60 min of wearing a stiff neck collar). In an additional replication experiment the effect of prolonged (120 min) hypokinesia on the eye reflexes were tested in 11 individuals. The COR did not change after 60 min of hypokinesia, but did increase after prolonged hypokinesia (median change 0.220; IQR 0.168,
p
= 0.017). The VOR increased after 60 min of hypokinesia (median change 0.155, IQR 0.26,
p
= 0.003), but this increase was gone after 120 min of hypokinesia. Both reflexes were unaffected by cervical hyperkinesia. Diminished neck movements influences both the COR and VOR, although on a different time scale. However, increased neck movements do not affect the reflexes. These findings suggest that diminished neck movements could cause the increased COR in patients with neck complaints.
In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the ...recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").
Abstract
Background
Slowness of walking is one of the very first signs of aging and is considered a marker for overall health that is strongly associated with mortality risk. In this study, we sought ...to disentangle the clinical drivers of the association between gait and mortality.
Methods
We included 4,490 participants of the Rotterdam Study who underwent a gait assessment between 2009 and 2015 and were followed-up for mortality until 2018. Gait was assessed with an electronic walkway and summarized into the domains Rhythm, Phases, Variability, Pace, Tandem, Turning, and Base of Support. Cox models adjusted for age, sex, and height were built and consecutively adjusted for six categories of health indicators (lifestyle, musculoskeletal, cardiovascular, pulmonary, metabolic, and neurological). Analyses were repeated in comorbidity-free individuals.
Results
Multiple gait domains were associated with an increased risk of mortality, including Pace (hazard ratio (HR) per SD worse gait, adjusted for other domains: 1.34 1.19–1.50), Rhythm (HR: 1.12 1.02–1.23) and Phases (HR: 1.12 1.03–1.21). Similarly, a 0.1 m/s decrease in gait speed was associated with a 1.21 (1.15–1.27) times higher hazard of mortality (HR fully adjusted: 1.14 1.08–1.20). In a comorbidity-free subsample, the HR per 0.1 m/s decrease in gait speed was 1.25 (1.09–1.44). Cause-specific mortality analyses revealed an association between gait speed and multiple causes of death.
Conclusions
Several gait domains were associated with mortality risk, including Pace which primarily represents gait speed. The association between gait speed and mortality persisted after an extensive adjustment for covariates, suggesting that gait is a marker for overall health.
Background
Brain MRI‐markers are risk factors of dementia and decline in cognition and daily functioning. It is unknown to what extent the associations of brain MRI‐markers with cognition and daily ...functioning are part of the pathway leading to dementia. We aimed to investigate associations of brain MRI‐markers with change in cognition and daily functioning during 15 years of follow‐up, including their relation to dementia.
Design, Setting, and Participants
Four hundred and sixty three stroke‐free and non‐demented participants from the population‐based Rotterdam Study that underwent brain‐MRI, yielding brain volumetrics, between 1995 and 1996.
Measurements
We assessed cognition using the Mini‐Mental State Examination (MMSE) and daily functioning using instrumental and basic activities of daily living (IADL and BADL) up to seven times between 1990 and 2011. Analyses were performed both including and excluding incident demented participants.
Results
Smaller brain volume associated with larger decline in MMSE, IADL, and BADL. Larger white matter lesion volume associated with larger decline in MMSE. Frontal lobe volume associated strongest with decline in IADL and BADL, and temporal lobe volume with decline in MMSE. After excluding incident demented participants (n = 63), associations with IADL and BADL remained, while associations with MMSE disappeared.
Conclusions
Smaller brain volumes and larger white matter volume associate with larger decline in cognition and daily functioning, during 15 years of follow‐up. Importantly, the relation of brain volume with cognition, but not daily functioning, was driven by those individuals that ultimately developed dementia.
To identify neural networks associated with the use of a mirror to superimpose movement of 1 hand on top of a nonmoving contralateral hand (often referred to as mirror therapy or mirror-induced ...visual illusion).
A functional magnetic resonance imaging (fMRI) study of mirror-induced visual illusion of hand movements using a blocked design in a 1.5T magnetic resonance imaging scanner. Neural activation was compared in a no-mirror experiment and a mirror experiment. Both experiments consisted of blocks of finger tapping of the right hand versus rest. In the mirror experiment, movement of the left hand was simulated by mirror reflection of right hand movement.
University medical center.
Eighteen healthy subjects.
Not applicable.
Differences in fMRI activation between the 2 experiments.
In the mirror experiment, we found supplementary activation compared with the no-mirror experiment in 2 visual areas: the right superior temporal gyrus (STG) and the right superior occipital gyrus.
In this study, we found 2 areas uniquely associated with the mirror-induced visual illusion of hand movements: the right STG and the right superior occipital gyrus. The STG is a higher-order visual region involved in the analysis of biological stimuli and is activated by observation of biological motion. The right superior occipital gyrus is located in the secondary visual cortex within the dorsal visual stream. In the literature, the STG has been linked with the mirror neuron system. However, we did not find activation within the frontoparietal mirror neuron system to support further a link with the mirror neuron system. Future studies are needed to explore the mechanism of mirror induced visual illusions in patient populations in more detail.
We assessed the behavioral effects of environmental enrichment on contrast sensitivity, reflexive eye movements and on oculomotor learning in mice that were housed in an enriched environment for a ...period of 3 weeks. Research has shown that a larger cage and a more complex environment have positive effects on the welfare of laboratory mice and other animals held in captivity. It has also been shown that environmental enrichment affects various behavior and neuroanatomical and molecular characteristics. We found a clear effect on oculomotor learning. Animals that were housed in an enriched environment learned significantly faster than controls that were housed under standard conditions. In line with existing literature, the enriched group also outperformed the controls in behavioral tests for explorative behavior. Meanwhile, both visual and reflexive oculomotor performance in response to visual and vestibular stimuli was unaffected. This points toward an underlying mechanism that is specific for motor learning, rather than overall motor performance.
Abstract Gait is a complex sequence of movements, requiring cooperation of many brain areas, such as the motor cortex, somatosensory cortex, and cerebellum. However, it is unclear which connecting ...white matter tracts are essential for communication across brain areas to facilitate proper gait. Using diffusion tensor imaging, we investigated associations of microstructural organization in fourteen brain white matter tracts with gait, among 2330 dementia- and stroke-free community-dwelling individuals. Gait was assessed by electronic walkway and summarized into Global Gait, and seven gait domains. Higher white matter microstructure associated with higher Global Gait, Phases, Variability, Pace, and Turning. Microstructure in thalamic radiations, followed by association tracts and the forceps major, associated most strongly with gait. Hence, in community-dwelling individuals, higher white matter microstructure associated with better gait, including larger strides, more single support, less stride-to-stride variability, and less turning steps. Our findings suggest that intact thalamocortical communication, cortex-to-cortex communication, and interhemispheric visuospatial integration are most essential in human gait.
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