Joe Verghese

Quantitative gait markers and incident fall risk in older adults.

BACKGROUND Identifying quantitative gait markers of falls in older adults may improve diagnostic assessments and suggest novel intervention targets. METHODS We studied 597 adults aged 70 and older (mean age 80.5 years, 62% women) enrolled in an aging study who received quantitative gait assessments at baseline. Association of speed and six other gait markers (cadence, stride length, swing, double support, stride length variability, and swing time variability) with incident fall rate was studied using generalized estimation equation procedures adjusted for age, sex, education, falls, chronic illnesses, medications, cognition, disability as well as traditional clinical tests of gait and balance. RESULTS Over a mean follow-up period of 20 months, 226 (38%) of the 597 participants fell. Mean fall rate was 0.44 per person-year. Slower gait speed (risk ratio [RR] per 10 cm/s decrease 1.069, 95% confidence interval [CI] 1.001-1.142) was associated with higher risk of falls in the fully adjusted models. Among six other markers, worse performance on swing (RR 1.406, 95% CI 1.027-1.926), double-support phase (RR 1.165, 95% CI 1.026-1.321), swing time variability (RR 1.007, 95% CI 1.004-1.010), and stride length variability (RR 1.076, 95% CI 1.030-1.111) predicted fall risk. The associations remained significant even after accounting for cognitive impairment and disability. CONCLUSIONS Quantitative gait markers are independent predictors of falls in older adults. Gait speed and other markers, especially variability, should be further studied to improve current fall risk assessments and to develop new interventions.

Quantitative gait dysfunction and risk of cognitive decline and dementia

Background: Identifying quantitative gait markers of preclinical dementia may lead to new insights into early disease stages, improve diagnostic assessments and identify new preventive strategies. Objective: To examine the relationship of quantitative gait parameters to decline in specific cognitive domains as well as the risk of developing dementia in older adults. Methods: We conducted a prospective cohort study nested within a community based ageing study. Of the 427 subjects aged 70 years and older with quantitative gait assessments, 399 were dementia-free at baseline. Results: Over 5 years of follow-up (median 2 years), 33 subjects developed dementia. Factor analysis was used to reduce eight baseline quantitative gait parameters to three independent factors representing pace, rhythm and variability. In linear models, a 1 point increase on the rhythm factor was associated with further memory decline (by 107%), whereas the pace factor was associated with decline on executive function measured by the digit symbol substitution (by 29%) and letter fluency (by 92%) tests. In Cox models adjusted for age, sex and education, a 1 point increase on baseline rhythm (hazard ratio (HR) 1.48; 95% CI 1.03 to 2.14) and variability factor scores (HR 1.37; 95% CI 1.05 to 1.78) was associated with increased risk of dementia. The pace factor predicted the risk of developing vascular dementia (HR 1.60; 95% CI 1.06 to 2.41). Conclusion: Our findings indicate that quantitative gait measures predict future risk of cognitive decline and dementia in initially non-demented older adults.

Validity of divided attention tasks in predicting falls in older individuals: A preliminary study

OBJECTIVES: Although cognitive impairment is known to be a major risk factor for falls in older individuals, the role of cognitive tests in predicting falls has not been established. Limited attentional resources may increase the risk for falls in older individuals. We examined the reliability and validity of divided attention tasks, walking while talking (WWT), in predicting falls.

Cognitive Processes Related to Gait Velocity: Results From the Einstein Aging Study

The authors examined the relationship between cognition and gait velocity, performed with and without interference, in elderly participants. Neuropsychological test scores from 186 cognitively normal elders were submitted to factor analysis that yielded 3 factors: Verbal IQ, Speed/Executive Attention, and Memory. Regression analyses revealed that these factors were significant predictors of variance in gait velocity, but the relationship varied as a function of task condition. All 3 factors predicted gait velocity without interference. However, the Speed/Executive Attention and Memory factors but not Verbal IQ predicted gait velocity in the interference condition. These findings suggest that gait velocity and cognitive function may have both shared and independent brain substrates. Future studies should explore gait velocity and cognitive function as predictors of dementia and falls.

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.

Epidemiology of Gait Disorders in Community‐Residing Older Adults

OBJECTIVES: To study the epidemiology of gait disorders in community‐residing older adults and their association with death and institutionalization.

Leisure activities and the risk of amnestic mild cognitive impairment in the elderly

Objective: To study the influence of leisure activity participation on risk of development of amnestic mild cognitive impairment (aMCI). Methods: The authors examined the relationship between baseline level of participation in leisure activities and risk of aMCI in a prospective cohort of 437 community-residing subjects older than 75 years, initially free of dementia or aMCI, using Cox analysis adjusted for age, sex, education, and chronic illnesses. The authors derived Cognitive and Physical Activity Scales based on frequency of participation in individual activities. Results: Over a median follow-up of 5.6 years, 58 subjects had development of aMCI. A one-point increase on the Cognitive (hazard ratio [HR] 0.95, 95% CI 0.91 to 0.99) but not Physical Activities Scale (HR 0.97, 95% CI 0.93 to 1.01) was associated with lower risk of aMCI. Subjects with Cognitive Activity scores in the highest (HR 0.46, 95% CI 0.24 to 0.91) and middle thirds (HR 0.52, 95% CI 0.29 to 0.96) had a lower risk of aMCI compared with subjects in the lowest third. The association persisted even after excluding subjects who converted to dementia within 2 years of meeting criteria for aMCI. Conclusions: Cognitive activity participation is associated with lower risk of development of amnestic mild cognitive impairment, even after excluding individuals at early stages of dementia.

Low blood pressure and the risk of dementia in very old individuals

Background: The role of blood pressure (BP) as a risk factor for dementia is complex and may be age dependent. In very old individuals, low BP might increase risk for dementia, perhaps by reducing cerebral perfusion pressure. Methods: The association between BP and dementia was examined in the Bronx Aging Study, a prospective study of 488 community-dwelling elderly individuals over age 75, dementia-free at baseline (1980 to 1983) and followed at 12- to 18-month intervals. Subjects with baseline BP and with at least one follow-up visit were included (n = 406). Incident dementia was diagnosed using the criteria of the Diagnostic and Statistical Manual of Mental Disorders (3rd rev. ed.). Results: Over 21 years (median 6.7 years), 122 subjects developed dementia (65 Alzheimer’s disease [AD], 28 vascular dementia, 29 other dementias). Relative risk of dementia increased for each 10-mm Hg decrement in diastolic (hazard ratio [HR] 1.20, 95% CI 1.03 to 1.40) and mean arterial (HR 1.16, 95% CI 1.02 to 1.32) pressure, adjusted for age, sex, and education. Low diastolic BP significantly influenced risk of developing AD but not vascular dementia. Upon examination of groups defined by BP, mildly to moderately raised systolic BP (140 to 179 mm Hg) was associated with reduced risk for AD (HR vs normal systolic BP group 0.55, 95% CI 0.32 to 0.96), whereas low diastolic BP (≤70 mm Hg) was associated with increased risk of AD (HR vs normal diastolic BP group 1.91, 95% CI 1.05 to 3.48). Subjects with persistent low BP over 2 years had higher risk of developing dementia (HR 2.19, 95% CI 1.27 to 3.77). Conclusions: Low diastolic pressure is associated with higher risk of dementia in elderly individuals over age 75. Dementia risk was higher in subjects with persistently low BP.

Alzheimer's Association recommendations for operationalizing the detection of cognitive impairment during the Medicare Annual Wellness Visit in a primary care setting

The Patient Protection and Affordable Care Act added a new Medicare benefit, the Annual Wellness Visit (AWV), effective January 1, 2011. The AWV requires an assessment to detect cognitive impairment. The Centers for Medicare and Medicaid Services (CMS) elected not to recommend a specific assessment tool because there is no single, universally accepted screen that satisfies all needs in the detection of cognitive impairment. To provide primary care physicians with guidance on cognitive assessment during the AWV, and when referral or further testing is needed, the Alzheimers Association convened a group of experts to develop recommendations. The resulting Alzheimers Association Medicare Annual Wellness Visit Algorithm for Assessment of Cognition includes review of patient Health Risk Assessment (HRA) information, patient observation, unstructured queries during the AWV, and use of structured cognitive assessment tools for both patients and informants. Widespread implementation of this algorithm could be the first step in reducing the prevalence of missed or delayed dementia diagnosis, thus allowing for better healthcare management and more favorable outcomes for affected patients and their families and caregivers.

The relationship between specific cognitive functions and falls in aging

The current study examined the relationship between cognitive function and falls in older people who did not meet criteria for dementia or mild cognitive impairment (N = 172). To address limitations of previous research, the authors controlled for the confounding effects of gait measures and other risk factors by means of associations between cognitive function and falls. A neuropsychological test battery was submitted to factor analysis, yielding 3 orthogonal factors (Verbal IQ, Speed/Executive Attention, Memory). Single and recurrent falls within the last 12 months were evaluated. The authors hypothesized that Speed/Executive Attention would be associated with falls. Additionally, the authors assessed whether associations between different cognitive functions and falls varied depending on whether single or recurrent falls were examined. Multivariate logistic regressions showed that lower scores on Speed/Executive Attention were associated with increased risk of single and recurrent falls. Lower scores on Verbal IQ were related only to increased risk of recurrent falls. Memory was not associated with either single or recurrent falls. These findings are relevant to risk assessment and prevention of falls and point to possible shared neural substrates of cognitive and motor function.