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1.
Appl Neuropsychol Child ; : 1-11, 2019 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-31268363

RESUMO

Using a longitudinal study design, a group of 94 adolescents participated in a visual search task and a visuospatial ability task yearly for four consecutive years. We analyzed the association between changes in visuospatial ability and changes in visual search performance and behavior and estimated additional effects of age and task repetition. Visuospatial ability was measured with the Design Organization Test (DOT). Search performance was analyzed in terms of reaction time and response accuracy. Search behavior was analyzed in terms of the number of fixations per trial, the saccade amplitude, and the distribution of fixations over different types of elements. We found that both the increase in age and the yearly repetition of the DOT had a positive effect on visuospatial ability. We show that the acceleration of visual search during childhood can be explained by the increase in visuospatial abilities with age during adolescence. With the yearly task repetition, visual search became faster and more accurate, while fewer fixations were made with larger saccade amplitudes. The combination of increasing visuospatial ability and task repetition makes visual search more effective and might increase the performance of many daily tasks during adolescence.

2.
Brain Stimul ; 2018 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-30497885

RESUMO

BACKGROUND: Changes in transcranial magnetic stimulation motor map parameters can be used to quantify plasticity in the human motor cortex. The golden standard uses a counting analysis of motor evoked potentials (MEPs) acquired with a predefined grid. Recently, digital reconstruction methods have been proposed, allowing MEPs to be acquired with a faster pseudorandom procedure. However, the reliability of these reconstruction methods has never been compared to the golden standard. OBJECTIVE: To compare the absolute reliability of the reconstruction methods with the golden standard. METHODS: In 21 healthy subjects, both grid and pseudorandom acquisition were performed twice on the first day and once on the second day. The standard error of measurement was calculated for the counting analysis and the digital reconstructions. RESULTS: The standard error of measurement was at least equal using digital reconstructions. CONCLUSION: Pseudorandom acquisition and digital reconstruction can be used in intervention studies without sacrificing reliability.

3.
eNeuro ; 5(4)2018 Jul-Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30073197

RESUMO

Individual variations in motor adaptation rate were recently shown to correlate with movement variability or "motor noise" in a forcefield adaptation task. However, this finding could not be replicated in a meta-analysis of adaptation experiments. Possibly, this inconsistency stems from noise being composed of distinct components that relate to adaptation rate in different ways. Indeed, previous modeling and electrophysiological studies have suggested that motor noise can be factored into planning noise, originating from the brain, and execution noise, stemming from the periphery. Were the motor system optimally tuned to these noise sources, planning noise would correlate positively with adaptation rate, and execution noise would correlate negatively with adaptation rate, a phenomenon familiar in Kalman filters. To test this prediction, we performed a visuomotor adaptation experiment in 69 subjects. Using a novel Bayesian fitting procedure, we succeeded in applying the well-established state-space model of adaptation to individual data. We found that adaptation rate correlates positively with planning noise (ß = 0.44; 95% HDI = [0.27 0.59]) and negatively with execution noise (ß = -0.39; 95% HDI = [-0.50 -0.30]). In addition, the steady-state Kalman gain calculated from planning and execution noise correlated positively with adaptation rate (r = 0.54; 95% HDI = [0.38 0.66]). These results suggest that motor adaptation is tuned to approximate optimal learning, consistent with the "optimal control" framework that has been used to explain motor control. Since motor adaptation is thought to be a largely cerebellar process, the results further suggest the sensitivity of the cerebellum to both planning noise and execution noise.

4.
J Vis ; 18(5): 3, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29715333

RESUMO

We studied changes in visual-search performance and behavior during adolescence. Search performance was analyzed in terms of reaction time and response accuracy. Search behavior was analyzed in terms of the objects fixated and the duration of these fixations. A large group of adolescents (N = 140; age: 12-19 years; 47% female, 53% male) participated in a visual-search experiment in which their eye movements were recorded with an eye tracker. The experiment consisted of 144 trials (50% with a target present), and participants had to decide whether a target was present. Each trial showed a search display with 36 Gabor patches placed on a hexagonal grid. The target was a vertically oriented element with a high spatial frequency. Nontargets differed from the target in spatial frequency, orientation, or both. Search performance and behavior changed during adolescence; with increasing age, fixation duration and reaction time decreased. Response accuracy, number of fixations, and selection of elements to fixate upon did not change with age. Thus, the speed of foveal discrimination increases with age, while the efficiency of peripheral selection does not change. We conclude that the way visual information is gathered does not change during adolescence, but the processing of visual information becomes faster.


Assuntos
Desenvolvimento do Adolescente/fisiologia , Movimentos Oculares/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Tempo de Reação/fisiologia , Adolescente , Adulto , Criança , Estudos Transversais , Feminino , Fixação Ocular/fisiologia , Humanos , Masculino
5.
Brain Stimul ; 11(4): 759-771, 2018 Jul - Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29680227

RESUMO

BACKGROUND: Cerebellar transcranial direct current stimulation has been reported to enhance motor associative learning and motor adaptation, holding promise for clinical application in patients with movement disorders. However, behavioral benefits from cerebellar tDCS have been inconsistent. OBJECTIVE: Identifying determinants of treatment success is necessary. BDNF Val66Met is a candidate determinant, because the polymorphism is associated with motor skill learning and BDNF is thought to mediate tDCS effects. METHODS: We undertook two cerebellar tDCS studies in subjects genotyped for BDNF Val66Met. Subjects performed an eyeblink conditioning task and received sham, anodal or cathodal tDCS (N = 117, between-subjects design) or a vestibulo-ocular reflex adaptation task and received sham and anodal tDCS (N = 51 subjects, within-subjects design). Performance was quantified as a learning parameter from 0 to 100%. We investigated (1) the distribution of the learning parameter with mixture modeling presented as the mean (M), standard deviation (S) and proportion (P) of the groups, and (2) the role of BDNF Val66Met and cerebellar tDCS using linear regression presented as the regression coefficients (B) and odds ratios (OR) with equally-tailed intervals (ETIs). RESULTS: For the eyeblink conditioning task, we found distinct groups of learners (MLearner = 67.2%; SLearner = 14.7%; PLearner = 61.6%) and non-learners (MNon-learner = 14.2%; SNon-learner = 8.0%; PNon-learner = 38.4%). Carriers of the BDNF Val66Met polymorphism were more likely to be learners (OR = 2.7 [1.2 6.2]). Within the group of learners, anodal tDCS supported eyeblink conditioning in BDNF Val66Met non-carriers (B = 11.9% 95%ETI = [0.8 23.0]%), but not in carriers (B = 1.0% 95%ETI = [-10.2 12.1]%). For the vestibulo-ocular reflex adaptation task, we found no effect of BDNF Val66Met (B = -2.0% 95%ETI = [-8.7 4.7]%) or anodal tDCS in either carriers (B = 3.4% 95%ETI = [-3.2 9.5]%) or non-carriers (B = 0.6% 95%ETI = [-3.4 4.8]%). Finally, we performed additional saccade and visuomotor adaptation experiments (N = 72) to investigate the general role of BDNF Val66Met in cerebellum-dependent learning and found no difference between carriers and non-carriers for both saccade (B = 1.0% 95%ETI = [-8.6 10.6]%) and visuomotor adaptation (B = 2.7% 95%ETI = [-2.5 7.9]%). CONCLUSIONS: The specific role for BDNF Val66Met in eyeblink conditioning, but not vestibulo-ocular reflex adaptation, saccade adaptation or visuomotor adaptation could be related to dominance of the role of simple spike suppression of cerebellar Purkinje cells with a high baseline firing frequency in eyeblink conditioning. Susceptibility of non-carriers to anodal tDCS in eyeblink conditioning might be explained by a relatively larger effect of tDCS-induced subthreshold depolarization in this group, which might increase the spontaneous firing frequency up to the level of that of the carriers.

6.
Nephrol Dial Transplant ; 33(12): 2165-2172, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-29566168

RESUMO

Background: Gait disturbance is proposed as a mechanism for higher risk of fall in kidney disease patients. We investigated the association of kidney function with gait pattern in the general population and tested whether the association between impaired kidney function and fall is more pronounced in subjects with lower gait function. Methods: We included 1430 participants (mean age: 60 years) from the Rotterdam Study. Kidney function was assessed using estimated glomerular filtration rate (eGFR) and albumin-to-creatinine ratio (ACR). We assessed global gait, gait velocity and seven independent gait domains: Rhythm, Phases, Variability, Pace, Tandem, Turning and Base of Support. Regression models adjusted for cardiometabolic and neurological factors were used. We evaluated whether participants with impaired kidney function and impaired gait fell more in the previous year. Results: The study population had a median (interquartile range) ACR of 3.6 (2.5-6.2) mg/g and mean ± SD eGFR of 87.6 ± 15 mL/min/1.73 m2. Higher ACR and lower eGFR were associated with lower global gait score [per doubling of ACR: -0.10, 95% confidence interval (CI): -0.14 to -0.06, and per SD eGFR:-0.09, 95% CI: -0.14 to -0.03] and slower gait speed (ACR: -1.44 cm/s, CI: -2.12 to -0.76; eGFR: -1.55 cm/s, CI: -2.43 to -0.67). Worse kidney function was associated with lower scores in Variability domain. The association between impaired kidney function and history of fall was present only in participants with lower gait scores [odds ratio (95% CI): ACR: 1.34 (1.09-1.65); eGFR: 1.58 (1.07-2.33)]. Conclusions: We observed a graded association between lower kidney function and impaired gait suggesting that individuals with decreased kidney function, even at an early stage, need to be evaluated for gait abnormalities and might benefit from fall prevention programmes.

7.
Cerebellum ; 17(4): 447-460, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29480507

RESUMO

Many fMRI studies have shown activity in the cerebellum after peripheral nociceptive stimulation. We investigated whether the areas in the cerebellum that were activated after nociceptive thumb stimulation were separate from those after nociceptive toe stimulation. In an additional experiment, we investigated the same for the anticipation of a nociceptive stimulation on the thumb or toe. For his purpose, we used fMRI after an electrical stimulation of the thumb and toe in 19 adult healthy volunteers. Following nociceptive stimulation, different areas were activated by stimulation on the thumb (lobule VI ipsilaterally and Crus II mainly contralaterally) and toe (lobules VIII-IX and IV-V bilaterally and lobule VI contralaterally), i.e., were somatotopically organized. Cerebellar areas innervated non-somatotopically by both toe and thumb stimulation were the posterior vermis and Crus I, bilaterally. In the anticipation experiment, similar results were found. However, here, the somatotopically activated areas were relatively small for thumb and negligible for toe stimulation, while the largest area was innervated non-somatotopically and consisted mainly of Crus I and lobule VI bilaterally. These findings indicate that nociceptive stimulation and anticipation of nociceptive stimulation are at least partly processed by the same areas in the cerebellum. This was confirmed by an additional conjunction analysis. Based on our findings, we hypothesize that input that is organized in a somatotopical manner reflects direct input from the spinal cord, while non-somatotopically activated parts of the cerebellum receive their information indirectly through cortical and subcortical connections, possibly involved in processing contextual emotional states, like the expectation of pain.

8.
Exp Brain Res ; 236(1): 297-304, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29147731

RESUMO

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.

9.
Appl Neuropsychol Child ; 7(2): 129-142, 2018 Apr-Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28075186

RESUMO

Cognitive functions mature at different points in time between birth and adulthood. Of these functions, visuospatial skills, such as spatial memory and part-to-whole organization, have often been tested in children and adults but have been less frequently evaluated during adolescence. We studied visuospatial memory and ability during this critical developmental period, as well as the correlation between these abilities, in a large group of 330 participants (aged 11 to 20 years, 55% male). To assess visuospatial memory, the participants were asked to memorize and reproduce sequences of random locations within a grid using a computer. Visuospatial ability was tested using a variation of the Design Organization Test (DOT). In this paper-and-pencil test, the participants had one minute to reproduce as many visual patterns as possible using a numerical code. On the memory task, compared with younger participants, older participants correctly reproduced more locations overall and longer sequences of locations, made fewer mistakes and needed less time to reproduce the sequences. In the visuospatial ability task, the number of correctly reproduced patterns increased with age. We show that both visuospatial memory and ability improve significantly throughout adolescence and that performance on both tasks is significantly correlated.


Assuntos
Desenvolvimento Infantil/fisiologia , Percepção Espacial/fisiologia , Memória Espacial/fisiologia , Percepção Visual/fisiologia , Adolescente , Distribuição por Idade , Fatores Etários , Análise de Variância , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Avaliação de Resultados (Cuidados de Saúde) , Estimulação Luminosa , Distribuição por Sexo , Adulto Jovem
11.
Neurology ; 89(1): 76-83, 2017 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-28566544

RESUMO

OBJECTIVE: To extensively investigate the association of chronic polyneuropathy with basic and instrumental activities of daily living (BADL and IADL), falls, and gait. METHODS: A total of 1,445 participants of the population-based Rotterdam Study (mean age 71 years, 54% women) underwent a polyneuropathy screening involving a symptom questionnaire, neurologic examination, and nerve conduction studies. Screening yielded 4 groups: no, possible, probable, and definite polyneuropathy. Participants were interviewed about BADL (Stanford Health Assessment questionnaire), IADL (Instrumental Activities of Daily Living scale), and frequency of falling in the previous year. In a random subset of 977 participants, gait was assessed with an electronic walkway. Associations of polyneuropathy with BADL and IADL were analyzed continuously with linear regression and dichotomously with logistic regression. History of falling was evaluated with logistic regression, and gait changes were evaluated with linear regression. RESULTS: Participants with definite polyneuropathy had more difficulty in performing BADL and IADL than participants without polyneuropathy. Polyneuropathy related to worse scores of all BADL components (especially walking) and 3 IADL components (housekeeping, traveling, and shopping). Participants with definite polyneuropathy were more likely to fall, and these falls more often resulted in injury. Participants with polyneuropathy had worse gait parameters on the walkway, including lower walking speed and cadence, and more errors in tandem walking. CONCLUSIONS: Chronic polyneuropathy strongly associates with impairment in the ability to perform daily activities and relates to worse gait and an increased history of falling.


Assuntos
Acidentes por Quedas/estatística & dados numéricos , Atividades Cotidianas , Transtornos Neurológicos da Marcha/epidemiologia , Polineuropatias/epidemiologia , Caminhada/estatística & dados numéricos , Ferimentos e Lesões/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Transtornos Neurológicos da Marcha/diagnóstico , Transtornos Neurológicos da Marcha/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Países Baixos/epidemiologia , Polineuropatias/complicações , Polineuropatias/diagnóstico , Ferimentos e Lesões/etiologia
12.
J Neurophysiol ; 118(2): 732-748, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28469001

RESUMO

Several studies have identified transcranial direct current stimulation (tDCS) as a potential tool in the rehabilitation of cerebellar disease. Here, we tested whether tDCS could alleviate motor impairments of subjects with cerebellar degeneration. Three groups took part in this study: 20 individuals with cerebellar degeneration, 20 age-matched controls, and 30 young controls. A standard reaching task with force-field perturbations was used to compare motor adaptation among groups and to measure the effect of stimulation of the cerebellum or primary motor cortex (M1). Cerebellar subjects and age-matched controls were tested during each stimulation type (cerebellum, M1, and sham) with a break of 1 wk among each of the three sessions. Young controls were tested during one session under one of three stimulation types (anodal cerebellum, cathodal cerebellum, or sham). As expected, individuals with cerebellar degeneration had a reduced ability to adapt to motor perturbations. Importantly, cerebellar patients did not benefit from anodal stimulation of the cerebellum or M1. Furthermore, no stimulation effects could be detected in aging and young controls. The present null results cannot exclude more subtle tDCS effects in larger subject populations and between-subject designs. Moreover, it is still possible that tDCS affects motor adaptation in cerebellar subjects and control subjects under a different task or with alternative stimulation parameters. However, for tDCS to become a valuable tool in the neurorehabilitation of cerebellar disease, stimulation effects should be present in group sizes commonly used in this rare patient population and be more consistent and predictable across subjects and tasks.NEW & NOTEWORTHY Transcranial direct current stimulation (tDCS) has been identified as a potential tool in the rehabilitation of cerebellar disease. We investigated whether tDCS of the cerebellum and primary motor cortex could alleviate motor impairments of subjects with cerebellar degeneration. The present study did not find stimulation effects of tDCS in young controls, aging controls, and individuals with cerebellar degeneration during reach adaptation. Our results require a re-evaluation of the clinical potential of tDCS in cerebellar patients.


Assuntos
Adaptação Fisiológica/fisiologia , Cerebelo/fisiopatologia , Atividade Motora/fisiologia , Córtex Motor/fisiopatologia , Degenerações Espinocerebelares/reabilitação , Estimulação Transcraniana por Corrente Contínua , Adolescente , Adulto , Idoso , Envelhecimento/fisiologia , Cerebelo/fisiologia , Estudos Cross-Over , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Motor/fisiologia , Transtornos dos Movimentos/fisiopatologia , Transtornos dos Movimentos/reabilitação , Reabilitação Neurológica/métodos , Degenerações Espinocerebelares/fisiopatologia , Estimulação Transcraniana por Corrente Contínua/métodos , Falha de Tratamento , Extremidade Superior/fisiologia , Extremidade Superior/fisiopatologia , Adulto Jovem
13.
Front Psychol ; 8: 476, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28424645

RESUMO

Background: Transcranial Direct Current Stimulation (tDCS) is a form of non-invasive electrical stimulation that changes neuronal excitability in a polarity and site-specific manner. In cognitive tasks related to prefrontal and cerebellar learning, cortical tDCS arguably facilitates learning, but the few studies investigating cerebellar tDCS, however, are inconsistent. Objective: We investigate the effect of cerebellar tDCS on performance of an implicit categorization learning task. Methods: Forty participants performed a computerized version of an implicit categorization learning task where squares had to be sorted into two categories, according to an unknown but fixed rule that integrated both the size and luminance of the square. Participants did one round of categorization to familiarize themselves with the task and to provide a baseline of performance. After that, 20 participants received anodal tDCS (20 min, 1.5 mA) over the right cerebellum, and 19 participants received sham stimulation and simultaneously started a second session of the categorization task using a new rule. Results: As expected, subjects performed better in the second session than in the first, baseline session, showing increased accuracy scores and reduced reaction times. Over trials, participants learned the categorization rule, improving their accuracy and reaction times. However, we observed no effect of anodal tDCS stimulation on overall performance or on learning, compared to sham stimulation. Conclusion: These results suggest that cerebellar tDCS does not modulate performance and learning on an implicit categorization task.

14.
Gait Posture ; 54: 248-254, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28359929

RESUMO

BACKGROUND: Hip and knee osteoarthritis (OA) are debilitating diseases that impair gait at severe stages. Although associations between OA and gait are established for normal walking, little is known about its relation with turning and tandem (heel-to-toe) walking. Furthermore, it is unknown how asymptomatic OA associates with gait, and whether associations differ by sex. We investigated how symptomatic and asymptomatic hip and knee OA associate with gait in community-dwelling individuals. METHODS: In 2706 participants of a population-based cohort study, gait was assessed by electronic walkway and summarised into seven gait domains. Hip and knee radiographs were graded for radiographic OA (ROA) using the Kellgren and Lawrence (K&L) score. Linear regression was used to investigate associations between ROA and gait. Analyses were repeated including only participants with asymptomatic ROA, defined as a K&L-score of 2 without pain. RESULTS: In total, 177 participants (6.5%) had hip ROA and 441 (16.3%) knee ROA. We found no associations of knee ROA with gait. Hip ROA associated with Rhythm, Tandem, and Turning. Furthermore, unilateral hip ROA associated with larger gait asymmetry and gait differences in osteoarthritic and non-osteoarthritic leg, when compared to people without hip ROA. Associations between hip ROA and gait were generally stronger for women than men. Associations for hip ROA remained after restricting to asymptomatic ROA. CONCLUSION: Hip ROA, but not knee ROA, associates with gait differences in normal walking, turning, and tandem walking in community-dwelling individuals. These associations differ between the sexes, and are already present for asymptomatic ROA.


Assuntos
Marcha/fisiologia , Osteoartrite do Quadril/fisiopatologia , Osteoartrite do Joelho/fisiopatologia , Caminhada/fisiologia , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Modelos Lineares , Masculino , Osteoartrite do Quadril/diagnóstico por imagem , Osteoartrite do Quadril/patologia , Osteoartrite do Joelho/patologia , Estudos Prospectivos , Fatores Sexuais
15.
Musculoskelet Sci Pract ; 29: 72-77, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28324698

RESUMO

BACKGROUND: Many chronic neck pain patients experience problems with vision. These problems are possibly induced by deviations of the eye stabilization reflexes. It is not known whether these eye reflex alterations occur both in traumatic and non-traumatic neck pain patients. OBJECTIVE: To investigate if the cervico-ocular reflex (COR) and the vestibulo-ocular reflex (VOR) are changed in tertiary care patients with prolonged, chronic neck pain with various origin of complaints. DESIGN: Cross sectional study. METHODS: Ninety-one chronic neck pain patients were subdivided into three groups by origin of complaints, and compared with healthy controls. COR and VOR gains were measured with an infrared eye tracking device with the subject sitting on a rotating chair in a darkened room and with the head fixed. RESULTS: Neck pain patients had a higher COR gain (median 0.41, IQR 0.289) compared with healthy controls (median 0.231, IQR 0.179). The mean COR gain did not differ between the three patient groups (Whiplash Associated Disorders 0.444 (SD 0.221); traumatic 0.397 (SD0.205); non-traumatic 0.468 (SD0.236)). There was no difference in VOR gain between the groups. CONCLUSION: Chronic neck pain patients, who already received primary care, still have an elevated cervico-ocular reflex. The origin of complaints did not seem to be associated with this deviant oculomotor behavior.


Assuntos
Dor Crônica/terapia , Fixação Ocular/fisiologia , Cervicalgia/complicações , Cervicalgia/terapia , Reflexo Vestíbulo-Ocular/fisiologia , Traumatismos em Chicotada/fisiopatologia , Adulto , Idoso , Estudos Transversais , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade
16.
J Am Geriatr Soc ; 65(6): 1258-1266, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28165615

RESUMO

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.


Assuntos
Atividades Cotidianas , Encéfalo/patologia , Cognição , Imagem por Ressonância Magnética/estatística & dados numéricos , Idoso , Transtornos Cognitivos/diagnóstico , Demência/diagnóstico , Progressão da Doença , Feminino , Humanos , Vida Independente , Estudos Longitudinais , Masculino , Países Baixos , Testes Neuropsicológicos/estatística & dados numéricos
17.
Aging (Albany NY) ; 9(1): 209-246, 2017 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-28077804

RESUMO

Emerging evidence suggests that the basis for variation in late-life mobility is attributable, in part, to genetic factors, which may become increasingly important with age. Our objective was to systematically assess the contribution of genetic variation to gait speed in older individuals. We conducted a meta-analysis of gait speed GWASs in 31,478 older adults from 17 cohorts of the CHARGE consortium, and validated our results in 2,588 older adults from 4 independent studies. We followed our initial discoveries with network and eQTL analysis of candidate signals in tissues. The meta-analysis resulted in a list of 536 suggestive genome wide significant SNPs in or near 69 genes. Further interrogation with Pathway Analysis placed gait speed as a polygenic complex trait in five major networks. Subsequent eQTL analysis revealed several SNPs significantly associated with the expression of PRSS16, WDSUB1 and PTPRT, which in addition to the meta-analysis and pathway suggested that genetic effects on gait speed may occur through synaptic function and neuronal development pathways. No genome-wide significant signals for gait speed were identified from this moderately large sample of older adults, suggesting that more refined physical function phenotypes will be needed to identify the genetic basis of gait speed in aging.


Assuntos
Envelhecimento/genética , Marcha/genética , Polimorfismo de Nucleotídeo Único , Velocidade de Caminhada/genética , Idoso , Idoso de 80 Anos ou mais , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Locos de Características Quantitativas , Proteínas Tirosina Fosfatases Classe 2 Semelhantes a Receptores/genética , Serina Endopeptidases/genética
18.
Sci Rep ; 6: 38912, 2016 12 14.
Artigo em Inglês | MEDLINE | ID: mdl-27966590

RESUMO

Gait is an important health indicator and poor gait is strongly associated with disability and risk of falls. Thyroid dysfunction is suggested as a potential determinant of gait deterioration, but this has not been explored in a population-based study. We therefore investigated the association of thyroid function with gait patterns in 2645 participants from the Rotterdam Study with data available on TSH (thyroid-stimulating hormone), FT4 (free thyroxine) and gait, without known thyroid disease or dementia. The primary outcome was Global gait (standardized Z-score), while secondary outcomes included gait domains (Rhythm, Variability, Phases, Pace, Base of support, Tandem, Turning) and velocity. Gait was assessed by electronic walkway. Multivariable regression models revealed an inverted U-shaped association of TSH (p < 0.001), but no association of FT4 concentrations with Global gait (p = 0.2). TSH levels were positively associated with Base of support (p = 0.01) and followed an inverted U-shaped curve with Tandem (p = 0.002) and velocity (p = 0.02). Clinical and subclinical hypothyroidism were associated with worse Global gait than euthyroidism (ß = -0.61; CI = -1.03, -0.18; p = 0.004 and ß = -0.13; CI = -0.26, -0.00; p = 0.04, respectively). In euthyroid participants, higher thyroid function was associated with worse gait patterns. In conclusion, both low and high thyroid function are associated with alterations in Global gait, Tandem, Base of support and velocity.


Assuntos
Marcha , Modelos Biológicos , Glândula Tireoide/metabolismo , Tireotropina/sangue , Tiroxina/sangue , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
19.
BMC Musculoskelet Disord ; 17(1): 441, 2016 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-27769215

RESUMO

BACKGROUND: Many people with Whiplash Associated Disorders (WAD) report problems with vision, some of which may be due to impaired eye movements. Better understanding of such impaired eye movements could improve diagnostics and treatment strategies. This systematic review surveys the current evidence on changes in eye movements of patients with WAD and explains how the oculomotor system is tested. METHODS: Nine electronic data bases were searched for relevant articles from inception until September 2015. All studies which investigated eye movements in patients with WAD and included a healthy control group were screened for inclusion. Qualifying studies were retrieved and independently assessed for methodological quality using the Methodology Checklists provided by the Scottish Intercollegiate Guidelines Network. RESULTS: Fourteen studies out of 833 unique hits were included. Ten studies reported impaired eye movements in patients with WAD and in four studies no differences compared to healthy controls were found. Different methods of eye movement examination were used in the ten studies: in five studies, the smooth pursuit neck torsion test was positive, in two more the velocity and stability of head movements during eye-coordination tasks were decreased, and in another three studies the cervico-ocular reflex was elevated. CONCLUSIONS: Overall the reviewed studies show deficits in eye movement in patients with WAD, but studies and results are varied. When comparing the results of the 14 relevant publications, one should realise that there are significant differences in test set-up and patient population. In the majority of studies patients show altered compensatory eye movements and smooth pursuit movements which may impair the coordination of head and eyes.


Assuntos
Medições dos Movimentos Oculares , Movimentos Oculares , Transtornos da Visão/diagnóstico , Traumatismos em Chicotada/complicações , Movimentos da Cabeça , Humanos , Pessoa de Meia-Idade , Nistagmo Optocinético , Reflexo Vestíbulo-Ocular , Transtornos da Visão/etiologia
20.
Invest Ophthalmol Vis Sci ; 57(8): 3554-66, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27379580

RESUMO

PURPOSE: Compensatory eye movements (CEM) maintain a stable image on the retina by minimizing retinal slip. The optokinetic reflex (OKR) and vestibulo-ocular reflex (VOR) compensate for low and high velocity stimuli, respectively. The OKR system is known to be highly nonlinear. The VOR is generally modeled as a linear system and assumed to satisfy the superposition and homogeneity principles. To probe CEM violation of the superposition principle, we recorded eye movement responses in C57BL/6 mice to sum of sine (SoS) stimulation, a combination of multiple nonharmonic inputs. METHODS: We tested the VOR, OKR, VVOR (visually enhanced VOR), and SVOR (suppressed VOR). We used stimuli containing 0.6 Hz, 0.8 Hz, 1.0 Hz, and 1.9 Hz. Power spectra of SoS stimuli did not yield distortion products. Gains and delays of SoS and single sine (SS) responses were compared to yield relative gains and delays. RESULTS: We find the superposition principle is violated primarily in the OKR, VOR, and SVOR conditions. In OKR, we observed relative gain suppression of the lower SoS stimulus frequency component irrespective of the absolute frequency. Conversely, SVOR and VOR results showed gain enhancement of the lower frequency component and overall decrease in lead. Visually enhanced VOR results showed trends for overall gain suppression and delay decrease. CONCLUSIONS: Compensatory eye movements arguably depend on predictive signals. These results may reflect better prediction for SS stimuli. Natural CEM system stimulation generally involves complex frequency spectra. Use of SoS stimuli is a step toward unravelling the signals that really drive CEM and the predictive algorithms they depend on.

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