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1.  A Common Cognitive Profile in Elderly Fallers and in Patients with Parkinson’s Disease: The Prominence of Impaired Executive Function and Attention 
Experimental aging research  2006;32(4):411-429.
The present study examined the cognitive profile of fallers relative to healthy controls and patients with Parkinson’s disease (PD), a positive control group, using a computerized battery. Fallers performed more poorly than controls on executive function, attention, and motor skills, but performed comparably on memory, information processing and the Mini Mental State Exam. A similar profile was evident for PD patients. However, unlike PD patients, fallers were abnormally inconsistent in their reaction times. These findings indicate that elderly fallers may have a unique cognitive processing deficit (i.e., variability of response timing) and underscore the importance of executive function and attention as potential targets for fall risk screening and interventions.
PMCID: PMC1868891  PMID: 16982571
cognitive function; aging; executive function; falls
2.  Overall reductions in functional brain activation are associated with falls in older adults: an fMRI study 
Falls are a common geriatric condition, and while impaired cognitive function has been identified as a key risk factor, the neural correlates that contribute to reduced executive functioning and falls currently remain unknown. In this study, community-dwelling adults aged 65–75 years were divided into two groups based on their recent history of falls (fallers versus non-fallers). All participants completed the Flanker task during functional magnetic resonance imaging (fMRI). We examined the hemodynamic response of congruent and incongruent trials separately in order to separate the relative contribution of each trial type as a function of falls history. We found that fallers exhibited a smaller difference in functional activation between congruent and incongruent trials relative to non-fallers, as well as an overall reduction in level of blood-oxygen-level dependent response. Of particular note, the medial frontal gyrus – a region implicated in motor planning – demonstrated hypo-activation in fallers, providing evidence that the prefrontal cortex might play a central role in falls risk in older adults.
PMCID: PMC3867665  PMID: 24391584
falls; older adults; fMRI; executive cognitive functions; Flanker task; medial frontal gyrus
3.  Age-related changes in the attentional control of visual cortex: A selective problem in the left visual hemifield 
Neuropsychologia  2011;49(7):1670-1678.
To what extent does our visual-spatial attention change with age? In this regard, it has been previously reported that relative to young controls, seniors show delays in attention-related sensory facilitation. Given this finding, our study was designed to examine two key questions regarding age-related changes in the effect of spatial attention on sensory-evoked responses in visual cortex –– are there visual field differences in the age-related impairments in sensory processing, and do these impairments co-occur with changes in the executive control signals associated with visual spatial orienting? Therefore, our study examined both attentional control and attentional facilitation in seniors (aged 66 to 74 years) and young adults (aged 18 to 25 years) using a canonical spatial orienting task. Participants responded to attended and unattended peripheral targets while we recorded event-related potentials (ERPs) to both targets and attention-directing spatial cues. We found that not only were sensory-evoked responses delayed in seniors specifically for unattended events in the left visual field as measured via latency shifts in the lateral occipital P1 elicited by visual targets, but seniors also showed amplitude reductions in the anterior directing attentional negativity (ADAN) component elicited by cues directing attention to the left visual field. At the same time, seniors also had significantly higher error rates for targets presented in the left vs. right visual field. Taken together, our data thus converge on the conclusion that age-related changes in visual spatial attention involve both sensory-level and executive attentional control processes, and that these effects appear to be strongly associated with the left visual field.
PMCID: PMC3514549  PMID: 21356222 CAMSID: cams2320
Aging; Visual-spatial attention; Attentional control; Event-related potentials
4.  Directing spatial attention to locations within remembered and imagined mental representations 
Spatial attention enables us to enhance the processing of items at target locations, at the expense of items presented at irrelevant locations. Many studies have explored the neural correlates of these spatial biases using event-related potentials (ERPs). More recently some studies have shown that these ERP correlates are also present when subjects search visual short-term memory (VSTM). This suggests firstly that this type of mental representation retains a spatial organization that is based upon that of the original percept, and secondly that these attentional biases are flexible and can act to modulate remembered as well as perceptual representations. We aimed to test whether it was necessary for subjects to have actually seen the memoranda at those spatial locations, or whether simply imagining the spatial layout was sufficient to elicit the spatial attention effects. On some trials subjects performed a “visual” search of an array held in VSTM, and upon other trials subjects imagined the items at those spatial locations. We found ERP markers of spatial attention in both the memory-search and the imagery-search conditions. However, there were differences between the conditions, the effect in the memory-search began earlier and included posterior electrode sites. By contrast the ERP effect in the imagery-search condition was apparent only over fronto-central electrode sites and emerged slightly later. Nonetheless, our data demonstrate that it is not necessary for subjects to have ever seen the items at spatial locations for neural markers of spatial attention to be elicited; searching an imaginary spatial layout also triggers spatially-specific attention effects in the ERP data.
PMCID: PMC3635023  PMID: 23630485
attention; ERPs; visual short-term memory; visual working memory; mental imagery
5.  Intervention to prevent further falls in older people who call an ambulance as a result of a fall: a protocol for the iPREFER randomised controlled trial 
An increasing number of falls result in an emergency call and the subsequent dispatch of paramedics. In the absence of physical injury, abnormal physiological parameters or change in usual functional status, it could be argued that routine conveyance by ambulance to the Emergency Department (ED) is not the most effective or efficient use of resources. Further, it is likely that non-conveyed older fallers have the potential to benefit from timely access to fall risk assessment and intervention. The aim of this randomised controlled trial is to evaluate the effect of a timely and tailored falls assessment and management intervention on the number of subsequent falls and fall-related injuries for non-conveyed older fallers.
Community dwelling people aged 65 years or older who are not conveyed to the ED following a fall will be eligible to be visited at home by a research physiotherapist. Consenting participants will receive individualised intervention strategies based on risk factors identified at baseline. All pre-test measures will be assessed prior to randomisation. Post-test measures will be undertaken by a researcher blinded to group allocation 6 months post-baseline. Participants in the intervention group will receive individualised pro-active fall prevention strategies from the clinical researcher to ensure that risk factors are addressed adequately and interventions carried out. The primary outcome measure will be the number of falls recorded by a falls diary over a 12 month period. Secondary outcome measures assessed six months after baseline will include the subsequent use of medical and emergency services and uptake of recommendations. Data will be analysed using the intention-to-treat principle.
As there is currently little evidence regarding the effectiveness or feasibility of alternate models of care following ambulance non-conveyance of older fallers, there is a need to explore assessment and intervention programs to help reduce subsequent falls, related injuries and subsequent use of health care services. By linking existing services rather than setting up new services, this pragmatic trial aims to utilise the health care system in an efficient and timely manner.
Trial registration
Australian New Zealand Clinical Trials Registry: ACTRN 12611000503921
PMCID: PMC3849451  PMID: 24070456
Ambulance; Accidental falls; Aged; Prevention; Intervention
6.  Gait disturbances as specific predictive markers of the first fall onset in elderly people: a two-year prospective observational study 
Falls are common in the elderly, and potentially result in injury and disability. Thus, preventing falls as soon as possible in older adults is a public health priority, yet there is no specific marker that is predictive of the first fall onset. We hypothesized that gait features should be the most relevant variables for predicting the first fall. Clinical baseline characteristics (e.g., gender, cognitive function) were assessed in 259 home-dwelling people aged 66 to 75 that had never fallen. Likewise, global kinetic behavior of gait was recorded from 22 variables in 1036 walking tests with an accelerometric gait analysis system. Afterward, monthly telephone monitoring reported the date of the first fall over 24 months. A principal components analysis was used to assess the relationship between gait variables and fall status in four groups: non-fallers, fallers from 0 to 6 months, fallers from 6 to 12 months and fallers from 12 to 24 months. The association of significant principal components (PC) with an increased risk of first fall was then evaluated using the area under the Receiver Operator Characteristic Curve (ROC). No effect of clinical confounding variables was shown as a function of groups. An eigenvalue decomposition of the correlation matrix identified a large statistical PC1 (termed “Global kinetics of gait pattern”), which accounted for 36.7% of total variance. Principal component loadings also revealed a PC2 (12.6% of total variance), related to the “Global gait regularity.” Subsequent ANOVAs showed that only PC1 discriminated the fall status during the first 6 months, while PC2 discriminated the first fall onset between 6 and 12 months. After one year, any PC was associated with falls. These results were bolstered by the ROC analyses, showing good predictive models of the first fall during the first six months or from 6 to 12 months. Overall, these findings suggest that the performance of a standardized walking test at least once a year is essential for fall prevention.
PMCID: PMC3933787  PMID: 24611048
risk of fall; gait analysis; gait variability; gait speed; accelerometric device; fall-related injuries; home-dwelling people; principal components analysis
7.  Prevalence and Determinants of Falls among Older Adults in Ecuador: An Analysis of the SABE I Survey 
The present study based on a nationally representative sample of older adults living in the Andes mountains and coastal region of the country indicates that 34.7% of older adults had fallen in the previous year in Ecuador. Among fallers, 30.6% reported a fall-related injury. The prevalence of falls was higher in women and among older adults residing in the rural Andes mountains. In the multivariate model, women, subjects with cognitive impairment, those reporting urinary incontinence, and those being physically active during the previous year were variables found independently associated with increased risk of falling among older adults in Ecuador. Moreover, a gradual and linear increase in the prevalence of falls was seen as the number of risk factors increased. Falls represent a major public health problem among older adults in Ecuador. The present findings may assist public health authorities to implement programs of awareness and fall prevention among older adults at higher risk of falls.
PMCID: PMC3580902  PMID: 23476643
8.  Postural Control Is Impaired in People with COPD: An Observational Study 
Physiotherapy Canada  2011;63(4):423-431.
Purpose: We investigated deficits in postural control and fall risk in people with chronic obstructive pulmonary disease (COPD).
Method: Twenty people with moderate to severe COPD (mean age 72.3 years, standard deviation [SD] 6.7 years) with a mean forced expiratory volume in 1 second (FEV1) of 46.7% (SD 13%) and 20 people (mean age 68.2 years, SD 8.1) who served as a comparison group were tested for postural control using the Sensory Organization Test (SOT). A score of zero in any trial of the SOT was registered as a fall. On the basis of the SOT results, participants were categorized as frequent fallers (two or more falls) or as fallers (one fall). To explore the potential influence of muscle weakness on postural control, knee extensors concentric muscle torque was assessed with an isokinetic dynamometer. Physical activity level was assessed with the Physical Activity Scale for the Elderly.
Results: People with COPD showed a 10.8% lower score on the SOT (p=0.016) and experienced more falls (40) than the comparison group (12). The proportion of frequent fallers and fallers during the SOT was greater (p=0.021) in the COPD group (four of 10) than in the comparison group (two of seven). People with COPD showed deficits in knee extensors muscle strength (p=0.01) and a modest trend toward reduced physical activity level. However, neither of these factors explained the deficits in postural control observed in the COPD group.
Conclusions: People with COPD show deficits in postural control and increased risk of falls as measured by the SOT. The deficits in postural control appear to be independent of muscle weakness and level of physical activity. Postural control interventions and fall risk strategies in the pulmonary rehabilitation of COPD are recommended.
PMCID: PMC3207981  PMID: 22942519
falls, accidental; muscle strength; balance, postural; proprioception; pulmonary disease; chronic obstructive; appareil vestibulaire; balancement postural; équilibre postural; force musculaire; maladie respiratoire; proprioception
9.  Functional neural correlates of reduced physiological falls risk 
It is currently unclear whether the function of brain regions associated with executive cognitive processing are independently associated with reduced physiological falls risk. If these are related, it would suggest that the development of interventions targeted at improving executive neurocognitive function would be an effective new approach for reducing physiological falls risk in seniors.
We performed a secondary analysis of 73 community-dwelling senior women aged 65 to 75 years old who participated in a 12-month randomized controlled trial of resistance training. Functional MRI data were acquired while participants performed a modified Eriksen Flanker Task - a task of selective attention and conflict resolution. Brain volumes were obtained using MRI. Falls risk was assessed using the Physiological Profile Assessment (PPA).
After accounting for baseline age, experimental group, baseline PPA score, and total baseline white matter brain volume, baseline activation in the left frontal orbital cortex extending towards the insula was negatively associated with reduced physiological falls risk over the 12-month period. In contrast, baseline activation in the paracingulate gyrus extending towards the anterior cingulate gyrus was positively associated with reduced physiological falls risk.
Baseline activation levels of brain regions underlying response inhibition and selective attention were independently associated with reduced physiological falls risk. This suggests that falls prevention strategies may be facilitated by incorporating intervention components - such as aerobic exercise - that are specifically designed to induce neurocognitive plasticity.
Trial Registration Identifier: NCT00426881
PMCID: PMC3178476  PMID: 21846395
10.  Can cognitive enhancers reduce the risk of falls in older people with Mild Cognitive Impairment? A protocol for a randomised controlled double blind trial 
BMC Neurology  2009;9:42.
Older adults with cognitive problems have a higher risk of falls, at least twice that of cognitively normal older adults. The consequences of falls in this population are very serious: fallers with cognitive problems suffer more injuries due to falls and are approximately five times more likely to be admitted to institutional care. Although the mechanisms of increased fall risk in cognitively impaired people are not completely understood, it is known that impaired cognitive abilities can reduce attentional resource allocation while walking. Since cognitive enhancers, such as cholinesterase inhibitors, improve attention and executive function, we hypothesise that cognitive enhancers may reduce fall risk in elderly people in the early stages of cognitive decline by improving their gait and balance performance due to an enhancement in attention and executive function.
Double blinded randomized controlled trial with 6 months follow-up in 140 older individuals with Mild Cognitive Impairment (MCI). Participants will be randomized to the intervention group, receiving donepezil, and to the control group, receiving placebo. A block randomization by four and stratification based on fall history will be performed. Primary outcomes are improvements in gait velocity and reduction in gait variability. Secondary outcomes are changes in the balance confidence, balance sway, attention, executive function, and number of falls.
By characterizing and understanding the effects of cognitive enhancers on fall risk in older adults with cognitive impairments, we will be able to pave the way for a new approach to fall prevention in this population. This RCT study will provide, for the first time, information regarding the effect of a medication designed to augment cognitive functioning have on the risk of falls in older adults with Mild Cognitive Impairment. We expect a significant reduction in the risk of falls in this vulnerable population as a function of the reduced gait variability achieved by treatment with cognitive enhancers. This study may contribute to a new approach to prevent and treat fall risk in seniors in early stages of dementia.
Trial Registration
The protocol for this study is registered with the Clinical Trials Registry, identifier number: NCT00934531
PMCID: PMC3224736  PMID: 19674471
11.  Exercise therapy for prevention of falls in people with Parkinson's disease: A protocol for a randomised controlled trial and economic evaluation 
BMC Neurology  2009;9:4.
People with Parkinson's disease are twice as likely to be recurrent fallers compared to other older people. As these falls have devastating consequences, there is an urgent need to identify and test innovative interventions with the potential to reduce falls in people with Parkinson's disease. The main objective of this randomised controlled trial is to determine whether fall rates can be reduced in people with Parkinson's disease using exercise targeting three potentially remediable risk factors for falls (reduced balance, reduced leg muscle strength and freezing of gait). In addition we will establish the cost effectiveness of the exercise program from the health provider's perspective.
230 community-dwelling participants with idiopathic Parkinson's disease will be recruited. Eligible participants will also have a history of falls or be identified as being at risk of falls on assessment. Participants will be randomly allocated to a usual-care control group or an intervention group which will undertake weight-bearing balance and strengthening exercises and use cueing strategies to address freezing of gait. The intervention group will choose between the home-based or support group-based mode of the program. Participants in both groups will receive standardized falls prevention advice. The primary outcome measure will be fall rates. Participants will record falls and medical interventions in a diary for the duration of the 6-month intervention period. Secondary measures include the Parkinson's Disease Falls Risk Score, maximal leg muscle strength, standing balance, the Short Physical Performance Battery, freezing of gait, health and well being, habitual physical activity and positive and negative affect schedule.
No adequately powered studies have investigated exercise interventions aimed at reducing falls in people with Parkinson's disease. This trial will determine the effectiveness of the exercise intervention in reducing falls and its cost effectiveness. This pragmatic program, if found to be effective, has the potential to be implemented within existing community services.
Trial registration
The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12608000303347).
PMCID: PMC2637228  PMID: 19161631
12.  Attentional Capture by Irrelevant Transients Leads to Perceptual Errors in a Competitive Change Detection Task 
Theories on visual change detection imply that attention is a necessary but not sufficient prerequisite for aware perception. Misguidance of attention due to salient irrelevant distractors can therefore lead to severe deficits in change detection. The present study investigates the mechanisms behind such perceptual errors and their relation to error processing on higher cognitive levels. Participants had to detect a luminance change that occasionally occurred simultaneously with an irrelevant orientation change in the opposite hemi-field (conflict condition). By analyzing event-related potentials in the EEG separately in those error prone conflict trials for correct and erroneous change detection, we demonstrate that only correct change detection was associated with the allocation of attention to the relevant luminance change. Erroneous change detection was associated with an initial capture of attention toward the irrelevant orientation change in the N1 time window and a lack of subsequent target selection processes (N2pc). Errors were additionally accompanied by an increase of the fronto-central N2 and a kind of error negativity (Ne or ERN), which, however, peaked prior to the response. These results suggest that a strong perceptual conflict by salient distractors can disrupt the further processing of relevant information and thus affect its aware perception. Yet, it does not impair higher cognitive processes for conflict and error detection, indicating that these processes are independent from awareness.
PMCID: PMC3360465  PMID: 22654780
attention; awareness; N2pc; error negativity
13.  Consequences of Magnocellular Dysfunction on Processing Attended Information in Schizophrenia 
Cerebral Cortex (New York, NY)  2012;22(6):1282-1293.
Schizophrenia is associated with perceptual and cognitive dysfunction including impairments in visual attention. These impairments may be related to deficits in early stages of sensory/perceptual processing, particularly within the magnocellular/dorsal visual pathway. In the present study, subjects viewed high and low spatial frequency (SF) gratings designed to test functioning of the parvocellular/magnocellular pathways, respectively. Schizophrenia patients and healthy controls attended to either the low SF (magnocellularly biased) or high SF (parvocellularly biased) gratings. Functional magnetic resonance imaging (fMRI) and recordings of event-related potentials (ERPs) were carried out during task performance. Patients were impaired at detecting low-frequency targets. ERP amplitudes to low-frequency gratings were diminished, both for the early sensory-evoked components and for the attend minus unattend difference component (the selection negativity), which is regarded as a neural index of feature-selective attention. Similarly, fMRI revealed that activity in extrastriate visual cortex was reduced in patients during attention to low, but not high, SF. In contrast, activity in frontal and parietal areas, previously implicated in the control of attention, did not differ between patients and controls. These findings suggest that impaired sensory processing of magnocellularly biased stimuli lead to impairments in the effective processing of attended stimuli, even when the attention control systems themselves are intact.
PMCID: PMC3357176  PMID: 21840846
attention; ERP; fMRI; magnocellular; schizophrenia
14.  Multiple component interventions for preventing falls and fall-related injuries among older people: systematic review and meta-analysis 
BMC Geriatrics  2014;14:15.
Limited attention has been paid in the literature to multiple component fall prevention interventions that comprise two or more fixed combinations of fall prevention interventions that are not individually tailored following a risk assessment. The study objective was to determine the effect of multiple component interventions on fall rates, number of fallers and fall-related injuries among older people and to establish effect sizes of particular intervention combinations.
Medline, EMBASE, CINAHL, PsychInfo, Cochrane, AMED, UK Clinical Research Network Study Portfolio, Current Controlled Trials register and Australian and New Zealand Clinical Trials register were systematically searched to August 2013 for randomised controlled trials targeting those aged 60 years and older with any medical condition or in any setting that compared multiple component interventions with no intervention, placebo or usual clinical care on the outcomes reported falls, number that fall or fall-related injuries. Included studies were appraised using the Cochrane risk of bias tool. Estimates of fall rate ratio and risk ratio were pooled across studies using random effects meta-analysis. Data synthesis took place in 2013.
Eighteen papers reporting 17 trials were included (5034 participants). There was a reduction in the number of people that fell (pooled risk ratio = 0.85, 95% confidence interval (95% CI) 0.80 to 0.91) and the fall rate (pooled rate ratio = 0.80, 95% CI 0.72 to 0.89) in favour of multiple component interventions when compared with controls. There was a small amount of statistical heterogeneity (I2 = 20%) across studies for fall rate and no heterogeneity across studies examining number of people that fell.
This systematic review and meta-analysis of randomised controlled trials found evidence that multiple component interventions that are not tailored to individually assessed risk factors are effective at reducing both the number of people that fall and the fall rate. This approach should be considered as a service delivery option.
PMCID: PMC3928080  PMID: 24495705
Falls; Systematic review; Aged
15.  The history of falls and the association of the timed up and go test to falls and near-falls in older adults with hip osteoarthritis 
BMC Geriatrics  2007;7:17.
Falling accounts for a significant number of hospital and long-term care admissions in older adults. Many adults with the combination of advancing age and functional decline associated with lower extremity osteoarthritis (OA), are at an even greater risk. The purpose of this study was to describe fall and near-fall history, location, circumstances and injuries from falls in a community-dwelling population of adults over aged 65 with hip OA and to determine the ability of the timed up and go test (TUG) to classify fallers and near-fallers.
A retrospective observational study of 106 older men and women with hip pain for six months or longer, meeting a clinical criteria for the presence of hip OA at one or both hips. An interview for fall and near-fall history and administration of the TUG were administered on one occasion.
Forty-five percent of the sample had at least one fall in the past year, seventy-seven percent reported occasional or frequent near-falls. The majority of falls occurred during ambulation and ascending or descending steps. Forty percent experienced an injury from the fall. The TUG was not associated with history of falls, but was associated with near-falls. Higher TUG scores occurred for those who were older, less mobile, and with greater number of co-morbidities.
A high percentage of older adults with hip OA experience falls and near-falls which may be attributed to gait impairments related to hip OA. The TUG could be a useful screening instrument to predict those who have frequent near-falls, and thus might be useful in predicting risk of future falls in this population.
PMCID: PMC1936991  PMID: 17610735
16.  Risk Factors for Falls in HIV-Infected Persons 
The incidence of and risk factors for falls in human immunodeficiency (HIV)-1-infected persons are unknown.
Fall history during the prior 12 months, medical diagnoses, and functional assessments were collected on HIV-infected persons 45 to 65 years of age receiving effective antiretroviral therapy. Fall risk was evaluated using univariate and multivariate regression analyses.
Of 359 subjects, 250 persons (70%) reported no falls, 109 (30%) had ≥1 fall; 66 (18%) were recurrent fallers. Females, Caucasians, and smokers were more like to be recurrent fallers (p≤0.05). HIV-related characteristics including current and nadir CD4 T-cell count, estimated HIV duration, and Veterans Aging Cohort Study Index scores were not predictors of falls (all p≥0.09); didanosine recipients were more likely to be recurrent fallers (p=0.04). The odds of falling increased 1.7 for each comorbidity and 1.4 for each medication (p<0.001), and were higher in persons with cardiovascular disease, hypertension, dementia, neuropathy, arthritis, chronic pain, psychiatric disease, frailty or disability (all OR≥ 1.8; p≤0.05). Beta-blockers, antidepressants, anti-psychotics, sedatives, and opiates were independently associated with falling (all OR ≥2.7; p≤0.01). Female gender, diabetes, antidepressants, sedatives, opiates, didanosine, exhaustion, weight loss, and difficulty with balance were the most significant predictors of falls in logistic regression (all OR ≥2.5; p≤0.05).
Middle-aged HIV-infected adults have high fall risk. Multiple comorbidities, medications, and functional impairment were predictive of falls, but surrogate markers of HIV infection or an HIV-specific multimorbidity index were not. Fall risk should be assessed routinely as part the care of HIV-infected persons.
PMCID: PMC3496187  PMID: 23143526
HIV; aging; accidental falls
17.  Falls in people with chronic obstructive pulmonary disease: an observational cohort study 
Respiratory Medicine  2011;105(3):461-469.
Study objective
To investigate incidence, risk factors and impact of falls on health related quality of life (HRQoL) in patients with chronic obstructive pulmonary disease (COPD).
Observational cohort study
Patients completed these questionnaires at baseline and at 6-months: Medical Outcomes Study Short Form 36 (SF-36), Chronic Respiratory Questionnaire (CRQ), Activities Balance Confidence (ABC) Scale and a form to record demographic data, medications, co-morbidities, oxygen use, acute exacerbations, fall history and assistive device use. Physical activity was measured with the Physical Activity Scale for the Elderly (PASE) only at baseline. Fall incidence was monitored through monthly fall diaries. Patients were categorized as non-fallers (0 falls) or fallers (≥1 falls).
Data from 101 patients with a forced expiratory volume in one second of 46.4±21.6% predicted were analyzed. Thirty-two patients (31.7%) reported at least one fall during the 6-months. Fall incidence rate was 0.1 (95% CI:0.06 to 0.14) falls per person-month. Fallers tended to be older (p=0.04), female (p=0.04) and oxygen dependent (p=0.02), have a history of previous falls (p<0.001), more co-morbidities (p=0.007) and take more medications (p=0.001). Previous falls (OR=7.36; 95% CI:2.39 to 22.69) and diagnosis of coronary heart disease (OR=7.07; 95% CI:2.14 to 23.36) were the most important predictors of falls. The Dyspnea Domain of the CRQ declined significantly more (p=0.02) in the fallers group at 6-months.
Patients with COPD have a high susceptibility to falls, which is associated with a worsening of dyspnea perception as related to HRQoL. Fall prevention programs in COPD are recommended.
PMCID: PMC3350813  PMID: 20869227 CAMSID: cams2186
18.  Attention related performance in two cognitively different subgroups of patients with multiple sclerosis. 
To evaluate the underlying mechanisms of cognitive decline in multiple sclerosis, two clinically and demographically matched multiple sclerosis groups differing in cognitive status were assessed with attention related tasks. In addition to the attention tests recommended by the Cognitive Function Study Group of the American National Multiple Sclerosis Society, a test of sustained attention was used to evaluate the role of possible fatigue on cognitive performance. The cognitively mildly deteriorated group was slower than the cognitively preserved group and the controls on all tests of attention. The mildly deteriorated group did not, however, consistently differ from the other groups in the error scores of the attention tests. The preserved group exhibited slowness at the end of the visual vigilance test, but no deficits were found on the other attention related tests in this group. It is suggested that dissociable kinds of processing slowness are the origin of the deficits found on the attention tests in the two multiple sclerosis groups. Our preserved group exhibited signs of motor and fatigue related slowness, whereas the mildly deteriorated group also had extensive cognitive slowness. As sensitive indicators of cognitive slowness, attentional tests should be included in evaluation of the cognitive status of patients with multiple sclerosis.
PMCID: PMC1073605  PMID: 7608714
19.  Visual Complexity Attenuates Emotional Processing in Psychopathy: Implications for Fear-Potentiated Startle Deficits 
A long-standing debate is the extent to which psychopathy is characterized by a fundamental deficit in attention or emotion. We tested the hypothesis that the interplay of emotional and attentional systems is critical for understanding processing deficits in psychopathy. Sixty-three offenders were assessed using the Psychopathy Checklist: Screening Version. Event-related brain potentials (ERPs) and fear-potentiated startle (FPS) were collected while participants viewed pictures selected to disentangle an existing confound between perceptual complexity and emotional content in the pictures typically used to study fear deficits in psychopathy. As predicted, picture complexity moderated emotional processing deficits. Specifically, the affective-interpersonal features of psychopathy were associated with greater allocation of attentional resources to processing emotional stimuli at initial perception (visual N1) but only when picture stimuli were visually-complex. Despite this, results for the late positive potential indicated that emotional pictures were less attentionally engaging and held less motivational significance for individuals high in affective-interpersonal traits. This deficient negative emotional processing was observed later in their reduced defensive fear reactivity (FPS) to high-complexity unpleasant pictures. In contrast, the impulsive-antisocial features of psychopathy were associated with decreased sensitivity to picture complexity (visual N1) and unrelated to emotional processing as assessed by ERP and FPS. These findings are the first to demonstrate that picture complexity moderates FPS deficits and implicate the interplay of attention and emotional systems as deficient in psychopathy.
PMCID: PMC3326229  PMID: 22187225
psychopathy; fear-potentiated startle; visual complexity; emotion; ERP
20.  Fall Frequency and Risk Assessment in Early Parkinson’s Disease 
Parkinsonism & related disorders  2012;18(7):837-841.
We sought to define the frequency of falls in early PD and assess potential risk factors for falls in this population.
We analyzed the data from two randomized, placebo controlled trials (NET-PD FS1 and FS-TOO) of 413 individuals with early PD over 18 months of follow-up in FS1 and 12 months in FS-TOO. Falls were defined as any report of falls on the UPDRS or the adverse event log. We assessed the frequency of falls overall and by age. The relationship between prespecified fall risk markers and the probability of falling was assessed using logistic and multiple logistic regression. A hurdle Poisson model was used to jointly model the probability of remaining fall-free and the number of falls.
During the follow-up period, 23% of participants fell, and 11% were habitual fallers. In a multiple logistic regression model, age, baseline UPDRS Falling score, and baseline PDQ-39 scores were associated with subsequent fall risk (P <0.001). Similarly, in a hurdle Poisson regression model, age, baseline UPDRS falling item, and baseline PDQ-39 were all significantly related to the probability of falling, but only UPDRS falling >0 was associated with the number of falls.
Falls are frequent and are associated with impaired quality of life, even in early PD. Current standard rating scales do not sufficiently explain future fall risk in the absence of a prior fall history. New assessment methods for falls and postural instability are required to better evaluate this important problem in clinical trials and clinical practice.
PMCID: PMC3424355  PMID: 22542094
Falls; Parkinson’s disease
21.  The Mediolateral CoP Parameters can Differentiate the Fallers among the Community-dwelling Elderly Population 
[Purpose] Age-related mediolateral (ML) instability of static postural control in the elderly has been well studied. Recent studies have provided evidence that ML center of pressure (CoP) parameters during dynamic postural control are more sensitive for differentiation of the fallers in the elderly. However, very limited studies have been done in which ML stability differences between fallers and non-fallers were investigated. The purpose of this study was to investigate the differences in ML CoP parameters between elderly fallers and elderly non-fallers during dynamic postural control. [Subjects and Methods] Twenty-nine community-dwelling older adults were divided into either fallers or non-fallers according to a self-report related to falling history within a year. Every participant performed 4 different tasks (static postural control tasks comprising quiet stance with eyes open and eyes closed and dynamic postural control tasks comprising stance with arm lifting and with trunk flexion) on force plates. [Results] The fallers demonstrated decreased AP and ML CoP parameters, and ML CoP distance was significantly smaller than in the non-fallers during both dynamic postural control tasks. [Conclusions] ML CoP parameters were able to differentiate the fallers from the non-fallers in a community-dwelling elderly population.
PMCID: PMC3976007
Fall predictors; Mediolateral stability; CoP parameters
22.  Abnormal late visual responses and alpha oscillations in neurofibromatosis type 1: a link to visual and attention deficits 
Neurofibromatosis type 1 (NF1) affects several areas of cognitive function including visual processing and attention. We investigated the neural mechanisms underlying the visual deficits of children and adolescents with NF1 by studying visual evoked potentials (VEPs) and brain oscillations during visual stimulation and rest periods.
Electroencephalogram/event-related potential (EEG/ERP) responses were measured during visual processing (NF1 n = 17; controls n = 19) and idle periods with eyes closed and eyes open (NF1 n = 12; controls n = 14). Visual stimulation was chosen to bias activation of the three detection mechanisms: achromatic, red-green and blue-yellow.
We found significant differences between the groups for late chromatic VEPs and a specific enhancement in the amplitude of the parieto-occipital alpha amplitude both during visual stimulation and idle periods. Alpha modulation and the negative influence of alpha oscillations in visual performance were found in both groups.
Our findings suggest abnormal later stages of visual processing and enhanced amplitude of alpha oscillations supporting the existence of deficits in basic sensory processing in NF1. Given the link between alpha oscillations, visual perception and attention, these results indicate a neural mechanism that might underlie the visual sensitivity deficits and increased lapses of attention observed in individuals with NF1.
PMCID: PMC3944002  PMID: 24559228
Visual evoked potentials; Alpha rhythm; Contrast response function; Electroencephalogram (EEG); Neurofibromatosis type 1 (NF1); Paediatric
23.  Executive function predicts risk of falls in older adults without balance impairment 
BMC Geriatrics  2011;11:74.
Executive dysfunction has previously been found to be a risk factor for falls. The aim of this study is to investigate the association between executive dysfunction and risk of falling and to determine if this association is independent of balance.
Participants were 188 community-dwelling individuals aged 65 and older. All participants underwent baseline and annual evaluations with review of health history, standardized neurologic examination, neuropsychological testing, and qualitative and quantitative assessment of motor function. Falls were recorded prospectively using weekly online health forms.
During 13 months of follow-up, there were 65 of 188 participants (34.6%) who reported at least one fall. Univariate analysis showed that fallers were more likely to have lower baseline scores in executive function than non-fallers (p = 0.03). Among participants without balance impairment we found that higher executive function z-scores were associated with lower fall counts (p = 0.03) after adjustment for age, sex, health status and prior history of falls using negative binomial regression models. This relationship was not present among participants with poor balance.
Lower scores on executive function tests are a risk factor for falls in participants with minimal balance impairment. However, this effect is attenuated in individuals with poor balance where physical or more direct motor systems factors may play a greater role in fall risk.
PMCID: PMC3226437  PMID: 22070602
24.  Increased Cognitive Load Leads to Impaired Mobility Decisions in Seniors at Risk for Falls 
Psychology and aging  2011;26(2):253-259.
Successful mobility requires appropriate decision-making. Seniors with reduced executive functioning— such as senior fallers—may be prone to poor mobility judgments, especially under dual-task conditions. We classified participants as “At-Risk” and “Not-At-Risk” for falls using a validated physiological falls-risk assessment. Dual-task performance was assessed in a virtual reality environment where participants crossed a simulated street by walking on a manual treadmill while listening to music or conversing on a phone. Those “At-Risk” experienced more collisions with oncoming cars and had longer crossing times in the Phone condition compared to controls. We conclude that poor mobility judgments during a dual-task leads to unsafe mobility for those at-risk for falls.
PMCID: PMC3123036  PMID: 21463063
aging; cognitive load; falls risk; dual-task
25.  Falls and Fractures in the Elderly with Sinus Node Disease: The Impact of Pacemaker Implantation 
Background. Falls and fractures in the elderly are among the leading causes of disability. We investigated whether pacemaker implantation prevents falls in patients with SND in a large cohort of patients. Methods. Patient demographics and medical history were collected prospectively. Fall history was retrospectively reconstituted from available medical records. The 10-year probability for major osteoporotic fractures was calculated retrospectively from available medical records using the Swiss fracture risk assessment tool FRAX-Switzerland. Results. During a mean observation period of 2.3 years after implantation, the rates of fallers and injured fallers with fracture were reduced to 15% and 6%, respectively. This corresponds to a relative reduction in the number of fallers of 75% (P < 0.001) and of injured fallers of 63% (P = 0.014) after pacemaker implantation. Similarly, the number of falls was reduced from 60 (48%) before pacemaker implantation to 22 (18%) thereafter (relative reduction 63%, P = 0.035) and the number of falls with injury from 22 (18%) to 7 (6%), which corresponds to a relative reduction of 67%, P = 0.013. Conclusion. In patients with SND, pacemaker implantation significantly reduces the number of patients experiencing falls, the total number of falls, and the risk for osteoporotic fractures.
PMCID: PMC3488401  PMID: 23150844

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