Recovery of mobility function and life-space mobility after ischemic stroke: the MOBITEC-Stroke study protocol.

BACKGROUND: Stroke is a major cause of disability and stroke incidence increases with age. Stroke frequently results in permanent limitations of mobility, and, consequently, the need for the help of others in activities of daily living. In order to optimize rehabilitative efforts and their functional outcomes, detailed knowledge of the functional recovery process, regarding mobility, is needed. Objectives of the MOBITEC-Stroke study are: 1.) To characterize mobility, including lower extremity physical function (LEPF) and life space (the geospatial extent of all of a person's movements), and changes in mobility within the first year after stroke. 2.) To identify and characterize subgroups with different mobility trajectories. 3.) To evaluate whether changes in LEPF are associated with changes in life-space. 4.) To evaluate participants' reasons for going outdoors, transportation use, and assistance needed for outdoor movement. METHODS: Patients with incident first stroke who live in their own homes (target N = 59, based on sample size calculation) will be included in this cohort study. At 3, 6, 9, and 12 months after stroke a battery of mobility tests will be performed at the study centre, including laboratory-based tests of balance and strength, and quantitative gait analysis. Life-space assessment (including 1-week GPS measurements) will be performed in participants' real life. Semantic information on visited locations (reasons for going outdoors, transportation use, assistance needed) will be collected by using interactive digital maps. Linear mixed effects models will be used to model the trajectories of mobility measures for the total sample and for predefined subgroups. As an exploratory analysis, growth mixture models (GMMs) will be used to identify relevant subgroups with different trajectories. Linear mixed effect models will be used to test whether changes in LEPF parameters are associated with changes in life-space. Participants' motivation for going outdoors, transportation use, and assistance needed for outdoor mobility will be analysed descriptively. DISCUSSION: A comprehensive and detailed knowledge of recovery patterns will enable the planning of targeted and adaptively tailored rehabilitation measures. Information about patients' reasons for outdoor mobility will provide the opportunity to define individualized and patient-oriented rehabilitation goals. TRIAL REGISTRATION: ISRCTN85999967 (on 13 August 2020; retrospectively).

[Gait changes and fall risk]. / Gangveränderungen und Sturzrisiko.

Walking is a complex motor task generally performed automatically by older adults. Falls with or without serious consequences such as fractures or fear of falling can be the result. Gait analysis shows that even minor stride-to-stride variations increase the risk for falls. These gait changes are often too small to be detected during normal walking alone, but rather appear in combination with an additional task, the so-called dual tasking. Irregular gait is not an inevitability of older age, but can be improved by targeted interventions.

Balance training and multi-task performance in seniors.

Age-related impairment in gait patterns when simultaneously performing cognitive (CI) and/or motor (MI) interference tasks are associated with an increased risk of falling in seniors. The objective of this study was to investigate the impact of balance training (BT) on walking performance with and without concurrently performing a CI and/or MI task in seniors. Twenty healthy women (n=14) and men (n=6) were assigned to either an intervention (n=11, age 71.9+/-4.8 yrs) or a control group (n=9, age 74.9+/-6.3 yrs). The intervention group conducted a six week BT (3/week). Pre and post tests included the assessment of stride-to-stride variability during single (walking), dual (CI or MI+walking), and triple (CI+MI+walking) task walking on an instrumented walkway. BT resulted in statistically significant reductions in stride time variability under single (p=0.02, Delta34.8%) but not dual or triple-task walking. Significant improvements in the MI task (p=0.05, Delta39.1%), but not in the CI task were found while walking. Findings showed that improved performance during single-task walking did not transfer to walking under dual or triple-task conditions suggesting multi-task BT as an alternative training modality. Improvement of the secondary motor but not cognitive task may indicate the need for the involvement of motor and particularly cognitive tasks during BT.

Association of vitamin D deficiency with cognitive impairment in older women: cross-sectional study.

OBJECTIVE: The association between low serum 25-hydroxyvitamin D [25(OH)D] concentration and cognitive decline has been investigated by only a few studies, with mixed results. The objective of this cross-sectional population-based study was to examine the association between serum 25(OH)D deficiency and cognitive impairment while taking confounders into account. METHODS: The subjects, 752 women aged > or =75 years from the Epidémiologie de l'Ostéoporose (EPIDOS) cohort, were divided into 2 groups according to serum 25(OH)D concentrations (either deficient, <10 ng/mL, or nondeficient, > or =10 ng/mL). Cognitive impairment was defined as a Pfeiffer Short Portable Mental State Questionnaire (SPMSQ) score <8. Age, body mass index, number of chronic diseases, hypertension, depression, use of psychoactive drugs, education level, regular physical activity, and serum intact parathyroid hormone and calcium were used as potential confounders. RESULTS: Compared with women with serum 25(OH)D concentrations > or =10 ng/mL (n = 623), the women with 25(OH)D deficiency (n = 129) had a lower mean SPMSQ score (p < 0.001) and more often had an SPMSQ score <8 (p = 0.006). There was no significant linear association between serum 25(OH)D concentration and SPMSQ score (beta = -0.003, 95% confidence interval -0.012 to 0.006, p = 0.512). However, serum 25(OH)D deficiency was associated with cognitive impairment (crude odds ratio [OR] = 2.08 with p = 0.007; adjusted OR = 1.99 with p = 0.017 for full model; and adjusted OR = 2.03 with p = 0.012 for stepwise backward model). CONCLUSIONS: 25-Hydroxyvitamin D deficiency was associated with cognitive impairment in this cohort of community-dwelling older women.

Vitamin D and cognitive performance in adults: a systematic review.

Chronic low serum 25-hydroxyvitamin D (25OHD) concentrations are common in adults and are associated with numerous non-skeletal diseases. Vitamin D receptors (VDR) are located in the human cortex and hippocampus, which are key areas for cognition. The objective of this study was to systematically review all published data from the past 30 years which examined the association between serum 25OHD concentrations and cognitive performance in adults. An English and French Medline, PsycINFO and Cochrane Library search ranging from 1979 to 2008 indexed under the Medical Subject Heading (MeSH) terms 'Vitamin D' or 'Hydroxycholecalciferols' combined with the terms 'Dementia' or 'Cognition' or 'Cognition Disorders' or 'Delirium' or 'Memory' or 'Memory Disorders' or 'Orientation' or 'Executive Functions' or 'Attention' or 'Brain' or 'Neuropsychological Tests' was performed. Of the 99 selected studies, five observational studies met the selection criteria and were included in the final analysis. No prospective cohort study was found. The number of participants ranged from 32 to 9556 community-dwelling older adults (45-65% women). Three studies showed four significant positive associations between serum 25OHD concentrations and global cognitive functions, whereas three other studies exploring specific aspects of cognition showed 11 non-significant associations. This systematic review shows that the association between serum 25OHD concentrations and cognitive performance is not yet clearly established. The inconclusive results of the reviewed studies could be due to methodology, types of the cognitive tasks used and/or the cellular mechanisms of vitamin D.

Stops walking when talking: a predictor of falls in older adults?

The objective of this study was to systematically review all published articles examining the relationship between the occurrence of falls and changes in gait and attention-demanding task performance whilst dual tasking amongst older adults. An English and French Medline and Cochrane library search ranging from 1997 to 2008 indexed under 'accidental falls', 'aged OR aged, 80 and over', 'dual task', 'dual tasking', 'gait', 'walking', 'fall' and 'falling' was performed. Of 121 selected studies, fifteen met the selection criteria and were included in the final analysis. The fall rate ranged from 11.1% to 50.0% in retrospective studies and from 21.3% to 42.3% in prospective ones. Amongst the three retrospective and eight prospective studies, two and six studies, respectively, showed a significant relationship between changes in gait performance under dual task and history of falls. The predictive value for falling was particularly efficient amongst frail older adults compared with healthy subjects. Two prospective studies challenged the usefulness of the dual-task paradigm as a significant predictor compared to single task performance and three studies even reported that gait changes whilst dual tasking did not predict falls. The pooled odds ratio for falling was 5.3 (95% CI, 3.1-9.1) when subjects had changes in gait or attention-demanding task performance whilst dual tasking. Despite conflicting early reports, changes in performance whilst dual tasking were significantly associated with an increased risk for falling amongst older adults and frail older adults in particular. Description of health status, standardization of test methodology, increase of sample size and longer follow-up intervals will certainly improve the predictive value of dual-task-based fall risk assessment tests.

Physiological augmentation of amino acid-induced insulin secretion by GIP and GLP-I but not by CCK-8.

It was the aim of this study to test insulinotropic actions of cholecystokinin octapeptide (CCK-8), gastric inhibitory polypeptide (GIP), and glucagon-like peptide I (GLP-I)-(7--36) amide at basal glucose but physiologically elevated amino acid concentrations. Therefore, in nine fasting healthy volunteers, an amino acid mixture was infused intravenously (12.6 g/h over 120 min). On separate occasions, from 30 to 120 min, placebo (0.9% NaCl-1% human serum albumin), synthetic sulfated CCK-8 (0.5 pmol.kg-1.min-1), human GIP (1 pmol.kg-1.min-1), or GLP-I-(7--36) amide (0.3 pmol.kg-1.min-1) was infused intravenously to mimic physiological increments after a meal. The amino acid infusion lead to a small increment in plasma glucose from 4.8 +/- 0.2 to 5.0 +/- 0.2 mmol/l and significantly elevated insulin and C-peptide concentrations. GIP and GLP-I-(7--36) amide further stimulated insulin (1.8-fold, P = 0.0001 and 0.004, respectively) and C-peptide (1.3-fold, P = 0.0003 and 0.013, respectively), with a subsequent slight reduction in plasma glucose (P < 0.0001). Insulin and C-peptide then decreased again in parallel. CCK-8 was without effect on insulin and C-peptide levels. In conclusion, GIP and GLP-I-(7--36) amide are not only able to interact with elevated plasma glucose but are insulinotropic also with physiologically raised amino acid concentrations. Such an interaction could play a role after the ingestion of mixed meals. Cholecystokinin, on the other hand, is not a physiological incretin also under these conditions.