Gait dysfunction in mild cognitive impairment syndromes

Gait and cognition: a complementary approach to understanding brain function and the risk of falling

Until recently, clinicians and researchers have performed gait assessments and cognitive assessments separately when evaluating older adults, but increasing evidence from clinical practice, epidemiological studies, and clinical trials shows that gait and cognition are interrelated in older adults. Quantifiable alterations in gait in older adults are associated with falls, dementia, and disability. At the same time, emerging evidence indicates that early disturbances in cognitive processes such as attention, executive function, and working memory are associated with slower gait and gait instability during single- and dual-task testing and that these cognitive disturbances assist in the prediction of future mobility loss, falls, and progression to dementia. This article reviews the importance of the interrelationship between gait and cognition in aging and presents evidence that gait assessments can provide a window into the understanding of cognitive function and dysfunction and fall risk in older people in clinical practice. To this end, the benefits of dual-task gait assessments (e.g., walking while performing an attention-demanding task) as a marker of fall risk are summarized. A potential complementary approach for reducing the risk of falls by improving certain aspects of cognition through nonpharmacological and pharmacological treatments is also presented. Untangling the relationship between early gait disturbances and early cognitive changes may be helpful in identifying older adults at risk of experiencing mobility decline, falls, and progression to dementia.

The protective effects of executive functions and episodic memory on gait speed decline in aging defined in the context of cognitive reserve

OBJECTIVES

To evaluate whether levels of cognitive reserve (CR), as measured using the Wechsler Adult Intelligence Scale (WAIS)-III vocabulary test, moderated longitudinal associations between cognitive functions and decline in gait speed in a community-based cohort of older adults without dementia, specifically, whether the protective effect of executive function (EF) and episodic memory against decline in gait speed would be greater in individuals with higher CR.

DESIGN

Longitudinal (median number of repeated annual gait speed measures, 3; maximum number of visits, 7).

SETTING

General community.

PARTICIPANTS

Seven hundred thirty-one community-residing individuals aged 70 and older without dementia were followed longitudinally with cognitive and gait evaluations at baseline and at annual visits.

MEASUREMENTS

Decline in gait speed (cm/s) served as the primary outcome. The Free and Cued Selective Reminding Test (FCSRT) was used to assess episodic memory. The Digit Symbol Substitution Test (DSST) was used to assess attention and EF. The vocabulary test served as a marker for CR.

RESULTS

Linear mixed effects model showed that gait speed declined over the follow-up period (P < .001). The significant three-way interactions of time by DSST by vocabulary (P = .01) and time by FCSRT by vocabulary (P = .02) revealed that levels of CR moderated the longitudinal associations between EF and episodic memory and gait speed decline.

CONCLUSION

The protective effects of EF and episodic memory against gait speed decline in aging are greater in individuals with higher CR.

Mild cognitive impairment as a predictor of falls in community-dwelling older people

OBJECTIVE

: Incidence of falls in people with cognitive impairment with or without a formal diagnosis of dementia is estimated to be twice that of cognitively intact older adults. This study aimed to investigate whether mild cognitive impairment (MCI) is associated with falls in older people.

DESIGN

: Prospective cohort study.

SETTING

: Community sample, Sydney Memory and Ageing Study.

PARTICIPANTS

: A total of 419 nondemented community-dwelling adults, age 70-90 years.

MEASUREMENTS

: A comprehensive neuropsychological test battery measuring four cognitive domains provided classification being with or without MCI on the basis of objective published criteria. Assessments of medical, physiologic, and psychological measures were also performed. Fallers were defined as people who had at least one injurious fall or at least two noninjurious falls during a 12-month follow-up period.

RESULTS

: Of the participants, 342 (81.6%) had normal cognitive functioning, 58 (13.8%) had nonamnestic MCI, and 19 (4.5%) had amnestic MCI. People with MCI performed worse than people without MCI in measures of general health and balance. Logistic regression analyses showed that fall risk was significantly greater in people with MCI (odds ratio [OR]: 1.72, 95% confidence interval [95% CI]: 1.03-2.89). This association was mainly apparent when the analysis was restricted to those with nonamnestic MCI (OR: 1.98, 95% CI: 1.11-3.53), where the relationship was primarily explained by impaired executive functioning (OR: 1.27, 95% CI: 1.02-1.59).

CONCLUSION

: The findings indicate that objectively defined MCI is an independent risk factor for injurious or multiple falls in a representative sample of community-dwelling older people. The presence of nonamnestic MCI, based primarily on executive function, was found to be an important factor in increasing fall risk.

Motoric cognitive risk syndrome and the risk of dementia

BACKGROUND

Despite growing evidence of links between gait and cognition in aging, cognitive risk assessments that incorporate motoric signs have not been examined. We sought to validate a new Motoric Cognitive Risk (MCR) syndrome to identify individuals at high risk of developing dementia.

METHODS

We evaluated 997 community residing individuals aged 70 and older participating in the Einstein Aging Study over a median follow-up time of 36.9 months. MCR syndrome was defined as presence of cognitive complaints and slow gait (one standard deviation below age- and sex-specific gait speed means) in nondemented individuals. Cox models were used to evaluate the effect of MCR syndrome on the risk of developing dementia and subtypes.

RESULTS

Fifty-two participants met criteria for MCR syndrome at baseline with a prevalence of 7% (95% CI: 5-9%). Prevalence of MCR increased with age. Participants with MCR were at higher risk of developing dementia (hazard ratio [HR] adjusted for age, sex, and education: 3.27, 95% CI: 1.55-6.90) and vascular dementia (adjusted HR: 12.81, 95% CI: 4.98-32.97). The association of MCR with risk of dementia or vascular dementia remained significant even after accounting for other confounders and diagnostic overlap with "cognitive" mild cognitive impairment syndrome subtypes.

CONCLUSIONS

A motor-based MCR syndrome provides a clinical approach to identify individuals at high risk for dementia, especially vascular dementia, to target for further investigations and who may benefit from preventive interventions.

In-home walking speeds and variability trajectories associated with mild cognitive impairment

OBJECTIVE

To determine whether unobtrusive long-term in-home assessment of walking speed and its variability can distinguish those with mild cognitive impairment (MCI) from those with intact cognition.

METHODS

Walking speed was assessed using passive infrared sensors fixed in series on the ceiling of the homes of elderly individuals participating in the Intelligent Systems for Assessing Aging Change (ISAAC) cohort study. Latent trajectory models were used to analyze weekly mean speed and walking speed variability (coefficient of variation [COV]).

RESULTS

ISAAC participants living alone included 54 participants with intact cognition, 31 participants with nonamnestic MCI (naMCI), and 8 participants with amnestic MCI at baseline, with a mean follow-up of 2.6 ± 1.0 years. Trajectory models identified 3 distinct trajectories (fast, moderate, and slow) of mean weekly walking speed. Participants with naMCI were more likely to be in the slow speed group than in the fast (p = 0.01) or moderate (p = 0.04) speed groups. For COV, 4 distinct trajectories were identified: group 1, the highest baseline and increasing COV followed by a sharply declining COV; groups 2 and 3, relatively stable COV; and group 4, the lowest baseline and decreasing COV. Participants with naMCI were more likely to be members of either highest or lowest baseline COV groups (groups 1 or 4), possibly representing the trajectory of walking speed variability for early- and late-stage MCI, respectively.

CONCLUSION

Walking speed and its daily variability may be an early marker of the development of MCI. These and other real-time measures of function may offer novel ways of detecting transition phases leading to dementia.

The physical performance test predicts aerobic capacity sufficient for independence in early-stage Alzheimer disease

BACKGROUND

Early identification of physical impairment related to Alzheimer disease (AD) is increasingly identified as an important aspect of diagnosis and care. Clinically accessible tools for evaluating physical capacity and impairment in AD have been developed but require further characterization for their effective use.

PURPOSE

To assess the utility of the Physical Performance Test (PPT) for identifying functionally limiting aerobic capacity in older adults with AD and without dementia.

METHODS

Secondary analysis of a dataset of community dwelling older adults, 70 without dementia and 60 with early-stage AD. Participants were administered the PPT and performed a graded maximal exercise test. The clinical utility of 2 versions of the PPT was described by determining sensitivity and specificity to functionally limiting aerobic capacity.

RESULTS

The 9-item PPT is predictive of diminished aerobic capacity in older adults with AD. A score of 28 or less indicates likelihood of functionally limiting aerobic capacity that would limit independent function with 67% sensitivity and 67% specificity. The 4-item mini-PPT demonstrates improved capability for identifying impaired functional aerobic capacity with 85% sensitivity and 62% specificity. The PPT was not useful for identifying impaired functional aerobic capacity in older adults without dementia.

CONCLUSIONS

The PPT, which incorporates basic and instrumental activities of daily living as test items, and the mini-PPT which focuses on basic activities of daily living and simple physical functions, are both clinically useful tool for the evaluation for individuals in the earliest stages of AD and both provide important information about functional performance. The mini-PPT additionally inform the clinician as to whether or not individual with early-stage AD is likely to have insufficient aerobic capacity to perform instrumental daily functions.

Approach to the elderly patient with gait disturbance

The prevalence of gait disturbances and falls increases dramatically with age, but these problems are not universal in the elderly. They should trigger a systematic search for underlying disease states, many of which can be treated medically or surgically, or significantly ameliorated through provision of physical therapy focused on gait training and aids to ambulation, removal of safety hazards in the environment, and the elimination of polypharmacy. While cardiovascular, orthopedic, and rheumatologic diseases account for the majority of gait disturbances in the elderly, the aim here is to outline an approach to the diagnosis and treatment of a broad array of neurologic conditions causing gait disturbance in the elderly.

Depressive symptoms and gait dysfunction in the elderly

OBJECTIVE

Assess the association between depressive symptoms (not meeting the criteria for major depression) and gait dysfunction in older adults.

DESIGN

Cross-sectional study.

SETTING

Einstein Aging Study, a community-based longitudinal aging study.

PARTICIPANTS

Six hundred ten nondemented and nondepressed community-residing adults age 70 and older.

MEASUREMENTS

Depressive symptoms measured using the 15-item Geriatric Depression Scale. To obtain a comprehensive assessment of gait, eight individual quantitative gait parameters were assessed: velocity (cm/s), stride length (cm), cadence (steps/min), swing phase (seconds), stance phase (seconds), double support phase (seconds), stride length variability (SD of stride length), and swing time variability (SD of swing time). Multiple linear regression analysis was applied to study the association of depressive symptoms with gait, adjusting for potential confounders including demographic variables, medical illnesses, and clinical gait abnormalities.

RESULTS

Increased level of depressive symptoms was associated with worse velocity, stride, and swing time variability. The relationship of the remaining five gait variables with depressive symptoms was not significant in the fully adjusted models.

CONCLUSIONS

Higher levels of depressive symptoms are associated with worse performance in specific quantitative gait variables in community-residing older adults.

Toward Automated, At-Home Assessment of Mobility Among Patients With Parkinson Disease, Using a Body-Worn Accelerometer

Objective. To develop an automated and objective method to assess mobility in Parkinson disease (PD) patients in daily-life settings and to investigate whether accelerometer-derived measures discriminate between PD and healthy controls as they walk and simulate activities of daily living (ADL). Methods. Healthy older adults (17) and patients with PD (22) wore a triaxial accelerometer on their lower back during short walks (validation study) and during a walk around the medical center to simulate daily activities (ADL simulation). The variability (consistency and rhythmicity) of stepping was assessed. The patients completed the walks before and after taking their anti-Parkinsonian medications. Frequency-based acceleration measures included dominant frequency, amplitude (strength of signal frequency), width (frequency dispersion), and slope (a combination reflecting amplitude and width) of the main frequency of the power spectral density in the 0.5- to 3.0-Hz band. A subset of the Unified Parkinson-Disease Rating Scale provided a clinical measure of gait impairment (UPDRS-Gait5). A PD patient and control wore the sensors for 3 days at home. Results. The width was larger, and the amplitude and slope were smaller in the PD patients compared to the controls in the validation study and ADL simulation ( P < .02). The width decreased, and the amplitude and slope increased when patients took anti-Parkinsonian medications ( P < .007). Significant correlations were observed between acceleration-derived measures and UPDRS-Gait5. The data obtained at home was similar to the clinic data. Conclusions. Frequency-derived measures are valid and sensitive estimates of stride-to-stride variability that can be used to assess the quality and consistency of walking in patients with PD in real-life settings.

Gait speed, body composition, and dementia. The EPIDOS-Toulouse cohort

BACKGROUND

Slow gait speed (GS) predicts dementia, but this association might be mediated by body composition parameters like total fat mass (TFM) or total lean mass (TLM). The aim of the study was to evaluate whether GS, TLM, and TFM were associated factors with an increased risk for subsequent dementia in community-dwelling older women.

METHODS

A case-control study was nested in the EPIDemiologie de l'OStéoporose cohort. GS (at usual pace more than 6 m), TLM, and TFM (assessed by dual energy x-ray absorptiometry) were measured at baseline. Cognitive performance was evaluated at baseline and at 7 years of follow-up. The presence of dementia was assured by two blinded memory experts based on best practice and validated criteria. Multivariate logistic regression models assessed the association of GS, TLM, and TFM with dementia risk.

RESULTS

Of the initial 1,462 women, 75 years old and older, 647 (43.4%) were cognitively intact at baseline and had a full cognitive assessment at 7 years (145 of them developed dementia). Controlled for covariates (demographics, physical activity, self-reported disabilities, and comorbidities), GS was an independent associated factor for subsequent dementia as a continuous variable (odds ratio [OR] 2.28, 95% CI: 1.32-3.94) and as a categorized variable (OR 2.38, 95% CI: 1.28-4.43 highest vs lowest quartile). Neither interaction with GS nor a statistically significant association with dementia risk was found for TLM and TFM.

CONCLUSIONS

GS was an independent associated factor for subsequent dementia not mediated by TLM or TFM.

Gait variability in older adults: a structured review of testing protocol and clinimetric properties

Gait variability (stride-to-stride fluctuations) is used increasingly as a marker for gait performance and future mobility status, cognitive status, and falls. This structured review explicitly examined literature that reported on the reliability, validity and responsiveness of gait variability in older adults. We searched Medline, Embase, Web of Science, Scopus, CINAHL, PEDRO, Biomechanics, SportDiscus and PsycInfo databases. Two independent reviewers undertook data extraction, with adjudication by a third reviewer in cases of disagreement. Twenty-two full papers were screened and 10 met the predefined inclusion criteria, involving 1036 participants who were mainly community dwelling older adults in their 8th decade. A wide range of gait variability parameters, testing protocols and calculations of gait variability were reported. Reliability estimates varied, but were mostly fair to moderate. Concurrent validity was established for stance time variability and change estimates were reported for stance time and swing time. Standard of reporting was generally poor, with insufficient detail provided for aspects of measurement and testing protocols. Further research is required to standardise testing procedures and establish reliability, responsiveness and validity for confident use of gait variability as a robust measure.

Verbal serial list learning in mild cognitive impairment: a profile analysis of interference, forgetting, and errors

Using cluster analysis Libon et al. (2010) found three verbal serial list-learning profiles involving delay memory test performance in patients with mild cognitive impairment (MCI). Amnesic MCI (aMCI) patients presented with low scores on delay free recall and recognition tests; mixed MCI (mxMCI) patients scored higher on recognition compared to delay free recall tests; and dysexecutive MCI (dMCI) patients generated relatively intact scores on both delay test conditions. The aim of the current research was to further characterize memory impairment in MCI by examining forgetting/savings, interference from a competing word list, intrusion errors/perseverations, intrusion word frequency, and recognition foils in these three statistically determined MCI groups compared to normal control (NC) participants. The aMCI patients exhibited little savings, generated more highly prototypic intrusion errors, and displayed indiscriminate responding to delayed recognition foils. The mxMCI patients exhibited higher saving scores, fewer and less prototypic intrusion errors, and selectively endorsed recognition foils from the interference list. dMCI patients also selectively endorsed recognition foils from the interference list but performed similarly compared to NC participants. These data suggest the existence of distinct memory impairments in MCI and caution against the routine use of a single memory test score to operationally define MCI.

Associations between physical performance and executive function in older adults with mild cognitive impairment: gait speed and the timed "up & go" test

BACKGROUND

Older adults with amnestic mild cognitive impairment (aMCI) are at higher risk for developing Alzheimer disease. Physical performance decline on gait and mobility tasks in conjunction with executive dysfunction has implications for accelerated functional decline, disability, and institutionalization in sedentary older adults with aMCI.

OBJECTIVES

The purpose of this study was to examine whether performance on 2 tests commonly used by physical therapists (usual gait speed and Timed "Up & Go" Test [TUG]) are associated with performance on 2 neuropsychological tests of executive function (Trail Making Test, part B [TMT-B], and Stroop-Interference, calculated from the Stroop Word Color Test) in sedentary older adults with aMCI.

DESIGN

The study was a cross-sectional analysis of 201 sedentary older adults with memory impairment participating in a longitudinal intervention study of cognitive function, aging, exercise, and health promotion.

METHODS

Physical performance speed on gait and mobility tasks was measured via usual gait speed and the TUG (at fast pace). Executive function was measured with the TMT-B and Stroop-Interference measures.

RESULTS

Applying multiple linear regression, usual gait speed was associated with executive function on both the TMT-B (β=-0.215, P=.003) and Stroop-Interference (β=-0.195, P=.01) measures, indicating that slower usual gait speed was associated with lower executive function performance. Timed "Up & Go" Test scores (in logarithmic transformation) also were associated with executive function on both the TMT-B (β=0.256, P<.001) and Stroop-Interference (β=0.228, P=.002) measures, indicating that a longer time on the TUG was associated with lower executive function performance. All associations remained statistically significant after adjusting for age, sex, depressive symptoms, medical comorbidity, and body mass index.

LIMITATIONS

The cross-sectional nature of this study does not allow for inferences of causation.

CONCLUSIONS

Physical performance speed was associated with executive function after adjusting for age, sex, and age-related factors in sedentary older adults with aMCI. Further research is needed to determine mechanisms and early intervention strategies to slow functional decline.

Gait and cognition in older adults: Insights from the Bronx and Kerala

Background:

Recent reports indicate that gait dysfunction can occur early in the course of cognitive decline suggesting that motor and cognitive functions in older adults may share common underlying brain substrates, pathological processes, and risk factors.

Objective:

This study was designed to report the association between gait and cognition in older adults in USA and the southern Indian state of Kerala.

Materials and Methods:

Literature review of gait and cognition studies conducted in Bronx County, USA as well as preliminary results from the Kerala-Einstein study (Kozhikode city, Kerala).

Results:

Review of published studies based in the Bronx shows that both clinical and quantitative gait dysfunction are common in older adults with cognitive impairment. Furthermore, clinical and quantitative gait dysfunction in cognitively normal older adults was a strong predictor of future cognitive decline and dementia. Our preliminary study in Kozhikode city shows that timed gait is slower in older adults diagnosed with dementia and mild cognitive impairment syndrome compared to healthy older controls.

Conclusions:

A strong association between gait and cognition is seen in seniors in USA as well as Kerala. A better understanding of the relationship between gait and cognition may help improve current diagnostic and therapeutic approaches globally.

Vascular cognitive impairment in small vessel disease: clinical and neuropsychological features of lacunar state and Binswanger's disease

BACKGROUND

ischaemic cerebrovascular small vessel disease (SVD) is a prevalent and under-diagnosed condition that triggers vascular cognitive impairment (VCI).

OBJECTIVE

to describe the neuropsychological and clinical profiles in SVD (Binswanger's disease, BD; lacunar state, LS) from the clinician's perspective at the VCI stage.

METHODS

a total of 1257 patients admitted to a tertiary center with a diagnosis of stroke, neuroradiological vascular disease, cognitive impairment/dementia, during a 13-year period were investigated. We prospectively assessed cognition in a subset of 141 patients with VCI (LS n = 28, BD n = 69, large vessel disease-LVD-n = 44) with MMSE, CAMDEX-H, WAIS-R, EXIT-25 and Trail making test.

RESULTS

executive dysfunction (ECD) (n = 89, 91.7% versus n = 10, 22.7%; P < 0.001) and gait disturbances (n = 74, 76.3% versus n = 15, 34.1%; P < 0.001) characterized SVD. Prior strokes (n = 9, 9.3% versus n = 23, 52.3%; P < 0.001) and embologenous cardiopathy (n = 39, 40.2% versus n = 28, 63.6%; P < 0.04) featured LVD cases. BD was defined by hypertension (n = 52, 75.4% versus n = 30, 44.1%; P < 0.001), ECD (n = 65, 94.2% versus n = 34, 47.2%; P < 0.001) and VCI onset with cognitive impairment but not strokes (n = 44, 63.8% versus n = 34, 50%; P < 0.01).

CONCLUSIONS

ECD and a frontal gait are SVD's clinical landmarks in our sample. LS and BD cases share a similar cognitive profile.

Predisability and gait patterns in older adults

Presence of performance inconsistency during repeated assessments of gait may reflect underlying subclinical disease, and help shed light on the earliest stages of disablement. We studied inter-session fluctuations on three selected gait measures (velocity, stride length, and stride length variability) during normal pace walking as well as during a cognitively demanding 'walking while talking' condition using a repeated measurement burst design (six sessions within a 2-week period) in 71 nondisabled and nondemented community residing older adults, 40 with predisability (does activities of daily living unassisted but with difficulty). Subjects with predisability had slower gait velocity and shorter stride length on both the normal and walking while talking conditions at baseline compared to nondisabled subjects. However, there was no significant pattern of fluctuations across the six sessions on the three selected gait variables comparing the two groups during normal walking as well as on the walking while talking conditions. Our findings support consistency of gait measurements during the earliest stages of disability.

The trajectory of gait speed preceding mild cognitive impairment

OBJECTIVES

To compare the trajectory of motor decline, as measured by gait speed and finger-tapping speed, between elderly people who developed mild cognitive impairment (MCI) and those who remained cognitively intact. We also sought to determine the approximate time at which the decline in motor function accelerated in persons who developed MCI.

DESIGN

Longitudinal cohort study.

PARTICIPANTS

Participants were 204 healthy seniors (57.8% women) from the Oregon Brain Aging Study evaluated for up to 20 years using annual neurologic, neuropsychological, and motor examinations.

MAIN OUTCOME MEASURES

The pattern of motor decline with aging was compared using a mixed-effects model with an interaction term for age and a clinical diagnosis of MCI. The time before diagnosis of MCI, when the change in gait or finger-tapping speed accelerates, was assessed using a mixed-effects model with a change point for men and women, separately and combined, who developed MCI.

RESULTS

The rates of change, with aging, in gait speed (P < .001) and finger-tapping speed in the dominant hand (P = .003) and nondominant hand (P < .001) were significantly different between participants who developed MCI (converters) and those who did not (nonconverters). Using a change point analysis for MCI converters, the decrease in gait speed accelerated by 0.023 m/s/y (P < .001), occurring 12.1 years before the onset of MCI. An acceleration in gait speed decline occurred earlier in men than women. For tapping speed, the change point occurred after the onset of MCI for both dominant and nondominant hands when men and women were combined.

CONCLUSIONS

Motor decline as indexed by gait speed accelerates up to 12 years before MCI. Longitudinal changes in motor function may be useful in the early detection of dementia during preclinical stages, when the utility of disease-modifying therapies would be greatest.

Conventional and robust quantitative gait norms in community-dwelling older adults

OBJECTIVES

To develop and compare norms for widely used gait parameters in adults aged 70 and older using cross-sectional (conventional) and longitudinal (robust) approaches accounting for important confounders such as disease effects on gait.

DESIGN

Cohort study.

SETTING

General community.

PARTICIPANTS

Community-dwelling older adults (> 70, N = 824) without dementia or disability.

MEASUREMENTS

Eight quantitative gait parameters measured using an instrumented walkway.

RESULTS

Of the 824 subjects (conventional normal (CN) sample), 304 were included in a "robust normal" (RN) sample after excluding those with prevalent or incident clinical gait abnormalities developing within 1 year of the baseline assessment to account for disease effects on gait performance. Descriptively, the RN sample showed better performance on all selected gait variables than the CN sample. For instance, mean gait velocity ± standard deviation was 105.9 ± 17.9 cm/s in the RN sample, compared with 93.3 ± 23.2 cm/s in the overall CN sample. Applying one standard deviation below the mean (70.1 cm/s) derived from the CN sample to define slow gait, 15.9% (131) in the overall cohort were classified as abnormal, whereas the RN cut-off (88.0 cm/s) classified 39.7% (327) in the overall cohort as abnormal.

CONCLUSION

Cross-sectional conventional norms may underestimate gait performance in aging. Longitudinal robust norms provide more-accurate estimates of normal gait performance and thus may improve early detection of gait disorders in older adults.

Cognition and the risk of hospitalization for serious falls in the elderly: results from the Cardiovascular Health Study

BACKGROUND

Many elderly adults fall every year, sometimes resulting in serious injury and hospitalization. Although impaired cognition is a risk factor for injurious falls, little is known about cognitive decline above the threshold of impairment and risk of serious falls in community-dwelling seniors.

METHODS

In total, 702 of 5,356 older adults participating in the Cardiovascular Health Study experienced an injurious fall between 1990 and 2005, as indicated by hospitalization records. General cognition was measured annually with the Modified Mini-Mental State Examination and processing speed with the Digit Symbol Substitution Test. The Cox regression model was used to calculate hazard ratio and 95% confidence interval with and without time-dependent covariates and adjusted for known risk factors.

RESULTS

Participants with slightly decreased Digit Symbol Substitution Test scores were at increased risk for a serious fall (hazard ratio = 1.58, 95% confidence interval = 1.15-2.17). The risk continued to increase with each quartile decrease in Digit Symbol Substitution Test score. Participants without prevalent cardiovascular disease at baseline and decreased Modified Mini-Mental State Examination scores (80-89) had a 45% increased risk for a serious fall and those at high risk for dementia (<80) were at twice the risk as participants scoring above 90 (hazard ratio = 2.16, 95% confidence interval = 1.60-2.91).

CONCLUSIONS

Both decreased general cognition and decreased processing speed appear to be potential risk factors for serious falls in the elderly. When assessing the risk of serious falls in elderly patients, clinicians should consider usual factors like gait instability and sensory impairment as well as less obvious ones such as cardiovascular disease and cognitive function in nondemented adults.

Profile of hippocampal volumes and stroke risk varies by neuropsychological definition of mild cognitive impairment

Wide-ranging conceptual and diagnostic approaches to defining mild cognitive impairment (MCI) have led to highly variable prevalence and progression rates. We sought to examine whether bilateral hippocampal volumes and cerebrovascular risk factors in individuals characterized by two different neuropsychological definitions of MCI subtypes would also differ. Participants were 65 nondemented, community-dwelling, older adults, ages 62-91 years, drawn from a larger group of individuals enrolled in a longitudinal study of normal aging. A comprehensive neuropsychological definition of MCI that required the presence of more than one impaired score in a cognitive domain resulted in expected anatomical results; hippocampal volumes were significantly smaller in the aMCI group as compared to cognitively normal or nonamnestic MCI participants. However, a typical definitional scheme for classifying MCI based only on the presence of one impaired score within a cognitive domain did not result in hippocampal differences between groups. Global stroke risk factors did not differ between the two definitional schemes, although the relationship between stroke risk variables and neuropsychological performance did vary by diagnostic approach. The comprehensive approach demonstrated associations between stroke risk and cognition, whereas the typical approach did not. Use of more sophisticated clinical decision-making and diagnostic approaches that incorporate comprehensive neuropsychological assessment techniques is supported by this convergence of neuropsychological, neuropathological, and stroke risk findings.

Spatial and temporal gait parameters in Alzheimer's disease and aging

Spatial and temporal gait parameters in 40 patients with early Alzheimer's disease (AD) were compared to that of 34 normal controls (NC) on a level ground and on a treadmill. Over-ground velocity, cycle-time, cadence, stride-length, stride-width and double-support time were captured on an electronic walkway. On the treadmill, cadence, cycle-time and double-support time were recorded at a preferred velocity using footswitches. The AD group were significantly slower on the Timed Up and Go task compared to NC (p<0.05). AD patients differed significantly from the NC on their over-ground gait velocity (99+/-19 cm/s vs 119+15 cm/s, p<0.001), cadence (101+/-9 steps/min vs 109+/-9 steps/min, p=0.001) and stride-length (118+/-18 cm vs 131+/-17 cm, p<0.01). On the treadmill, only preferred speed was significantly different in the AD group compared to the NC group (60+/-20 cm/s vs 74+/-23 cm/s, p=0.02). These results indicate that patients with early AD walk slower and with shorter strides than healthy older adults.

Managing gait disorders in older persons residing in nursing homes: a review of literature

Managing gait disorders in the nursing home setting is a challenge. Nursing home residents can present with a variety of factors that may contribute to the presentation of gait abnormalities. The development of an individualized intervention program can be effective in improving a resident's ability to ambulate. This article reviews the research pertaining to the management of gait disorders including deconditioning, therapeutic exercise intervention, dementia, and cardiovascular and cardiopulmonary systems. The review provides the reader with strategies to help improve and understand gait performance in older persons residing in nursing homes.

Contributions of neuropsychology and neuroimaging to understanding clinical subtypes of mild cognitive impairment

The original conceptualization of mild cognitive impairment (MCI) was primarily as an amnestic disorder representing an intermediate stage between normal aging and Alzheimer's dementia (AD). More recently, broader conceptualizations of MCI have emerged that also encompass cognitive domains other than memory. These characterizations delineate clinical subtypes that commonly include amnestic and non-amnestic forms, and that involve single and multiple cognitive domains. With the advent of these broader classifications, more specific information is emerging regarding the neuropsychological presentation of individuals with MCI, risk for dementia associated with different subtypes of MCI, and neuropathologic substrates connected to the clinical subtypes. This review provides an overview of this burgeoning literature specific to clinical subtypes of MCI. Focus is primarily on neuropsychological and structural neuroimaging findings specific to clinical subtypes of MCI as well as the issue of daily functioning. Although investigations of non-amnestic subtypes using advanced neuroimaging techniques and clinical trials are quite limited, we briefly review these topics in MCI because these data provide a framework for future investigations specifically examining additional clinical subtypes of MCI. Finally, the review comments on select methodological issues involved in studying this heterogeneous population, and future directions to continue to improve our understanding of MCI and its clinical subtypes are offered.