OBJECTIVES Although several studies suggest that slow gait speed is a predictor of falls, it may also be a protective mechanism to prevent falls. Further, fast walking may precipitate falls. Therefore, we examined the relationship between gait speed and falls risk. DESIGN Longitudinal analysis of the association between gait speed and subsequent falls and analysis of gait speed decline as a predictor of future falls SETTING Population-based cohort study PARTICIPANTS 763 community-dwelling elders underwent baseline assessments and were followed for falls. Of these, 600 completed an 18-month follow-up assessment to determine change in gait speed and were followed for subsequent falls. MEASUREMENTS Gait speed was measured during a 4-meter walk, falls data were collected from monthly post-card calendars, and covariates were collected from in-home and clinic visits. RESULTS There was a U-shaped relation between gait speed and falls with faster (≥1.3 m/s, incident rate ratio (IRR) = 2.12, 95% CI = 1.48 – 3.04) and slower speeds (<0.6 m/sec, IRR = 1.60, CI = 1.06 – 2.42) at highest risk compared to normal gait speeds (≥1.0 and < 1.3 m/sec). In adjusted analyses, slower gait speeds were associated with an increased risk ratio for indoor falls (for <0.6 m/sec, IRR = 2.17, CI = 1.33 – 3.55 and for ≥0.6 and <1.0 m/sec, IRR = 1.45, CI = 1.08 – 1.94). Faster gait speed was associated with an increased risk ratio for outdoor falls (IRR = 2.11, CI = 1.40 – 3.16). A gait speed decline of >0.15 m/sec/year predicted an increased risk for all falls (IRR = 1.86, CI = 1.15 – 3.01). CONCLUSION There is a non-linear relation between gait speed and falls with a greater risk of outdoor falls in faster walkers and greater risk of indoor falls in slow walkers.

OBJECTIVETo determine acute effects of intranasal insulin on regional cerebral perfusion and cognition in older adults with type 2 diabetes mellitus (DM).RESEARCH DESIGN AND METHODSThis was a proof-of-concept, randomized, double-blind, placebo-controlled intervention evaluating the effects of a single 40-IU dose of insulin or saline on vasoreactivity and cognition in 15 DM and 14 control subjects. Measurements included regional perfusion, vasodilatation to hypercapnia with 3-Tesla MRI, and neuropsychological evaluation.RESULTSIntranasal insulin administration was well tolerated and did not affect systemic glucose levels. No serious adverse events were reported. Across all subjects, intranasal insulin improved visuospatial memory (P ≤ 0.05). In the DM group, an increase of perfusion after insulin administration was greater in the insular cortex compared with the control group (P = 0.0003). Cognitive performance after insulin administration was related to regional vasoreactivity. Improvements of visuospatial memory after insulin administration in the DM group (R2adjusted = 0.44, P = 0.0098) and in the verbal fluency test in the control group (R2adjusted = 0.64, P = 0.0087) were correlated with vasodilatation in the middle cerebral artery territory.CONCLUSIONSIntranasal insulin administration appears safe, does not affect systemic glucose control, and may provide acute improvements of cognitive function in patients with type 2 DM, potentially through vasoreactivity mechanisms. Intranasal insulin-induced changes in cognitive function may be related to vasodilatation in the anterior brain regions, such as insular cortex that regulates attention-related task performance. Larger studies are warranted to identify long-term effects and predictors of positive cognitive response to intranasal insulin therapy.

Type 2 diabetes mellitus (T2DM) alters brain function and manifests as brain atrophy. Intranasal insulin has emerged as a promising intervention for treatment of cognitive impairment. We evaluated the acute effects of intranasal insulin on resting-state brain functional connectivity in older adults with T2DM. This proof-of-concept, randomized, double-blind, placebo-controlled study evaluated the effects of a single 40 IU dose of insulin or saline in 14 diabetic and 14 control subjects. Resting-state functional connectivity between the hippocampal region and default mode network (DMN) was quantified using functional MRI (fMRI) at 3Tesla. Following insulin administration, diabetic patients demonstrated increased resting-state connectivity between the hippocampal regions and the medial frontal cortex (MFC) as compared with placebo (cluster size: right, P = 0.03) and other DMN regions. On placebo, the diabetes group had lower connectivity between the hippocampal region and the MFC as compared with control subjects (cluster size: right, P = 0.02), but on insulin, MFC connectivity was similar to control subjects. Resting-state connectivity correlated with cognitive performance. A single dose of intranasal insulin increases resting-state functional connectivity between the hippocampal regions and multiple DMN regions in older adults with T2DM. Intranasal insulin administration may modify functional connectivity among brain regions regulating memory and complex cognitive behaviors.

BackgroundTai Chi training enhances physical function and may reduce falls in older adults with and without balance disorders, yet its effect on postural control as quantified by the magnitude or speed of center-of-pressure (COP) excursions beneath the feet is less clear. We hypothesized that COP metrics derived from complex systems theory may better capture the multi-component stimulus that Tai Chi has on the postural control system, as compared with traditional COP measures.MethodsWe performed a secondary analysis of a pilot, non-controlled intervention study that examined the effects of Tai Chi on standing COP dynamics, plantar sensation, and physical function in 25 older adults with peripheral neuropathy. Tai Chi training was based on the Yang style and consisted of three, one-hour group sessions per week for 24 weeks. Standing postural control was assessed with a force platform at baseline, 6, 12, 18, and 24 weeks. The degree of COP complexity, as defined by the presence of fluctuations existing over multiple timescales, was calculated using multiscale entropy analysis. Traditional measures of COP speed and area were also calculated. Foot sole sensation, six-minute walk (6MW) and timed up-and-go (TUG) were also measured at each assessment.ResultsTraditional measures of postural control did not change from baseline. The COP complexity index (mean±SD) increased from baseline (4.1±0.5) to week 6 (4.5±0.4), and from week 6 to week 24 (4.7±0.4) (p=0.02). Increases in COP complexity—from baseline to week 24—correlated with improvements in foot sole sensation (p=0.01), the 6MW (p=0.001) and TUG (p=0.01).ConclusionsSubjects of the Tai Chi program exhibited increased complexity of standing COP dynamics. These increases were associated with improved plantar sensation and physical function. Although more research is needed, results of this non-controlled pilot study suggest that complexity-based COP measures may inform the study of complex mind-body interventions, like Tai Chi, on postural control in those with peripheral neuropathy or other age-related balance disorders.

The number of patients suffering from dementia is expected to more than triple by the year 2040, and this represents a major challenge to publicly-funded healthcare systems throughout the world. One of the most effective prevention mechanisms against dementia lies in increasing brain- and cognitive-reserve capacity, which has been found to reduce the behavioral severity of dementia symptoms as neurological degeneration progresses. To date though, most of the factors known to enhance this reserve stem from largely immutable history factors, such as level of education and occupational attainment. Here, we review the potential for basic lifestyle activities, including physical exercise, meditation and musical experience, to contribute to reserve capacity and thus reduce the incidence of dementia in older adults. Relative to other therapies, these activities are low cost, are easily scalable and can be brought to market quickly and easily. Overall, although preliminary evidence is promising at the level of randomized control trials, the state of research on this topic remains underdeveloped. As a result, several important questions remain unanswered, including the amount of training required to receive any cognitive benefit from these activities and the extent to which this benefit continues following cessation. Future research directions are discussed for each lifestyle activity, as well as the potential for these and other lifestyle activities to serve as both a prophylactic and a therapeutic treatment for dementia.

Human aging into senescence diminishes the capacity of the postural control system to adapt to the stressors of everyday life. Diminished adaptive capacity may be reflected by a loss of the fractal-like, multiscale complexity within the dynamics of standing postural sway (i.e., center-of-pressure, COP). We therefore studied the relationship between COP complexity and adaptive capacity in 22 older and 22 younger healthy adults. COP magnitude dynamics were assessed from raw data during quiet standing with eyes open and closed, and complexity was quantified with a new technique termed empirical mode decomposition embedded detrended fluctuation analysis (EMD-DFA). Adaptive capacity of the postural control system was assessed with the sharpened Romberg test. As compared to traditional DFA, EMD-DFA more accurately identified trends in COP data with intrinsic scales and produced short and long-term scaling exponents (i.e., αShort, αLong) with greater reliability. The fractal-like properties of COP fluctuations were time-scale dependent and highly complex (i.e., αShort values were close to one) over relatively short time scales. As compared to younger adults, older adults demonstrated lower short-term COP complexity (i.e., greater αShort values) in both visual conditions (p>0.001). Closing the eyes decreased short-term COP complexity, yet this decrease was greater in older compared to younger adults (p<0.001). In older adults, those with higher short-term COP complexity exhibited better adaptive capacity as quantified by Romberg test performance (r2 = 0.38, p<0.001). These results indicate that an age-related loss of COP complexity of magnitude series may reflect a clinically important reduction in postural control system functionality as a new biomarker.

Major depressive disorder (MDD) is a worldwide cause of disability in older age, especially during the covid pandemic. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that has shown encouraging efficacy for treatment of depression. Here, we investigate the feasibility of an innovative protocol where tDCS is administered within the homes of older adults with MDD (patient participants) with the help of a study companion (i.e. caregiver). We further analyze the feasibility of a remotely-hosted training program that provides the knowledge and skills to administer tDCS at home, without requiring them to visit the lab. We also employed a newly developed multi-channel tDCS system with real-time monitoring designed to guarantee the safety and efficacy of home-based tDCS. Patient participants underwent a total of 37 home-based tDCS sessions distributed over 12 weeks. The protocol consisted of three phases each lasting four weeks: an acute phase, containing 28 home-based tDCS sessions, a taper phase containing nine home-based tDCS sessions, and a follow up phase, with no stimulation sessions. We found that the home-based, remotely-supervised, study companion administered, multi-channel tDCS protocol for older adults with MDD was feasible and safe. Further, the study introduces a novel training program for remote instruction of study companions in the administration of tDCS. Future research is required to determine the translatability of these findings to a larger sample.Clinical Trial Registration:https://clinicaltrials.gov/ct2/show/NCT04799405?term=NCT04799405&amp;draw=2&amp;rank=1, identifier NCT04799405.

Supporting the health of growing numbers of frail older adults living in subsidized housing requires interventions that can combat frailty, improve residents’ functional abilities, and reduce their health care costs. Tai Chi is an increasingly popular multimodal mind–body exercise that incorporates physical, cognitive, social, and meditative components in the same activity and offers a promising intervention for ameliorating many of the conditions that lead to poor health and excessive health care utilization. The Mind Body-Wellness in Supportive Housing (Mi-WiSH) study is an ongoing two-arm cluster randomized, attention-controlled trial designed to examine the impact of Tai Chi on functional indicators of health and health care utilization. We are enrolling participants from 16 urban subsidized housing facilities (n=320 participants), conducting the Tai Chi intervention or education classes and social calls (attention control) in consenting subjects within the facilities for one year, and assessing these subjects at baseline, 6 months, and 1 year. Physical function (quantified by the Short Physical Performance Battery), and health care utilization (emergency visits, hospitalizations, skilled nursing and nursing home admissions), assessed at 12 months are co-primary outcomes. Our discussion highlights our strategy to balance pragmatic and explanatory features into the study design, describes efforts to enhance site recruitment and participant adherence, and summarizes our broader goal of post study dissemination if effectiveness and cost-effectiveness are demonstrated, by preparing training and protocol manuals for use in housing facilities across the U.S.