Lien Quach

Cognitive trajectories after postoperative delirium.

BACKGROUND Delirium is common after cardiac surgery and may be associated with long-term changes in cognitive function. We examined postoperative delirium and the cognitive trajectory during the first year after cardiac surgery. METHODS We enrolled 225 patients 60 years of age or older who were planning to undergo coronary-artery bypass grafting or valve replacement. Patients were assessed preoperatively, daily during hospitalization beginning on postoperative day 2, and at 1, 6, and 12 months after surgery. Cognitive function was assessed with the use of the Mini-Mental State Examination (MMSE; score range, 0 to 30, with lower scores indicating poorer performance). Delirium was diagnosed with the use of the Confusion Assessment Method. We examined performance on the MMSE in the first year after surgery, controlling for demographic characteristics, coexisting conditions, hospital, and surgery type. RESULTS The 103 participants (46%) in whom delirium developed postoperatively had lower preoperative mean MMSE scores than those in whom delirium did not develop (25.8 vs. 26.9, P<0.001). In adjusted models, those with delirium had a larger drop in cognitive function (as measured by the MMSE score) 2 days after surgery than did those without delirium (7.7 points vs. 2.1, P<0.001) and had significantly lower postoperative cognitive function than those without delirium, both at 1 month (mean MMSE score, 24.1 vs. 27.4; P<0.001) and at 1 year (25.2 vs. 27.2, P<0.001) after surgery. With adjustment for baseline differences, the between-group difference in mean MMSE scores was significant 30 days after surgery (P<0.001) but not at 6 or 12 months (P=0.056 for both). A higher percentage of patients with delirium than those without delirium had not returned to their preoperative baseline level at 6 months (40% vs. 24%, P=0.01), but the difference was not significant at 12 months (31% vs. 20%, P=0.055). CONCLUSIONS Delirium is associated with a significant decline in cognitive ability during the first year after cardiac surgery, with a trajectory characterized by an initial decline and prolonged impairment. (Funded by the Harvard Older Americans Independence Center and others.).

Indoor and outdoor falls in older adults are different: the maintenance of balance, independent living, intellect, and Zest in the Elderly of Boston Study.

OBJECTIVES: To identify risk factors for indoor and outdoor falls.

Hypertension, White Matter Hyperintensities, and Concurrent Impairments in Mobility, Cognition, and Mood The Cardiovascular Health Study

Background— Our objective was to investigate the association between hypertension and concurrent impairments in mobility, cognition, and mood; the role of brain white matter hyperintensities in mediating this association; and the impact of these impairments on disability and mortality in elderly hypertensive individuals. Methods and Results— —Blood pressure, gait speed, digit symbol substitution test, and the Center for Epidemiological Studies Depression Scale were measured yearly (1992–1999) on 4700 participants in the Cardiovascular Health Study (age: 74.7, 58% women, 17% blacks, 68% hypertension, 3600 had brain magnetic resonance imaging in 1992–1993, survival data 1992–2005). Using latent profile analysis at baseline, we found that 498 (11%) subjects had concurrent impairments and 3086 (66%) were intact on all 3 measures. Between 1992 and 1999, 651 (21%) became impaired in all 3 domains. Hypertensive individuals were more likely to be impaired at baseline (odds ratio 1.23, 95% confidence interval 1.04 to 1.42, P=0.01) and become impaired during the follow-up (hazard ratio=1.3, 95% confidence interval 1.02 to 1.66, P=0.037). A greater degree of white matter hyperintensities was associated with impairments in the 3 domains (P=0.007) and mediated the association with hypertension (P=0.19 for hypertension after adjusting for white matter hyperintensities in the model, 21% hazard ratio change). Impairments in the 3 domains increased subsequent disability with hypertension (P<0.0001). Hypertension mortality also was increased in those impaired (compared with unimpaired hypertensive individuals: HR=1.10, 95% confidence interval 1.04 to 1.17, P=0.004). Conclusions— Hypertension increases the risk of concurrent impairments in mobility, cognition, and mood, which increases disability and mortality. This association is mediated in part by microvascular brain injury.

The Nonlinear Relationship Between Gait Speed and Falls: The Maintenance of Balance, Independent Living, Intellect, and Zest in the Elderly of Boston Study

OBJECTIVES: To examine the relationship between gait speed and falls risk.

Hypertension, White Matter Hyperintensities, and Concurrent Impairments in Mobility, Cognition, and Mood

Background— Our objective was to investigate the association between hypertension and concurrent impairments in mobility, cognition, and mood; the role of brain white matter hyperintensities in mediating this association; and the impact of these impairments on disability and mortality in elderly hypertensive individuals. Methods and Results— —Blood pressure, gait speed, digit symbol substitution test, and the Center for Epidemiological Studies Depression Scale were measured yearly (1992–1999) on 4700 participants in the Cardiovascular Health Study (age: 74.7, 58% women, 17% blacks, 68% hypertension, 3600 had brain magnetic resonance imaging in 1992–1993, survival data 1992–2005). Using latent profile analysis at baseline, we found that 498 (11%) subjects had concurrent impairments and 3086 (66%) were intact on all 3 measures. Between 1992 and 1999, 651 (21%) became impaired in all 3 domains. Hypertensive individuals were more likely to be impaired at baseline (odds ratio 1.23, 95% confidence interval 1.04 to 1.42, P=0.01) and become impaired during the follow-up (hazard ratio=1.3, 95% confidence interval 1.02 to 1.66, P=0.037). A greater degree of white matter hyperintensities was associated with impairments in the 3 domains (P=0.007) and mediated the association with hypertension (P=0.19 for hypertension after adjusting for white matter hyperintensities in the model, 21% hazard ratio change). Impairments in the 3 domains increased subsequent disability with hypertension (P<0.0001). Hypertension mortality also was increased in those impaired (compared with unimpaired hypertensive individuals: HR=1.10, 95% confidence interval 1.04 to 1.17, P=0.004). Conclusions— Hypertension increases the risk of concurrent impairments in mobility, cognition, and mood, which increases disability and mortality. This association is mediated in part by microvascular brain injury.

Stiffness control of balance during dual task and prospective falls in older adults: the MOBILIZE Boston Study.

Outdoor fallers differ from indoor fallers substantially in demographics, lifestyle, health condition and physical function. Biomechanical predictors of outdoor falls have not been well characterized. Current validated measures of postural deficits, which describe only the overall postural behavior, are predictive of indoor falls but not outdoor falls. We hypothesized that a model-based description of postural muscle tone and reflexes, particularly during dual tasking, would predict outdoor falls. We tested whether postural stiffness and damping from an inverted pendulum model were predictive of future indoor and outdoor falls among older adults from the MOBILIZE Boston Study. The center of pressure data during standing were obtained from 717 participants aged 77.9±5.3 years. Participants stood barefoot with eyes open for 30s per trial, in two sets of five standing trials. One set included a serial subtractions task. Postural stiffness and damping values were determined from the postural sway data. After the postural measurements, falls were monitored prospectively using a monthly mail-in calendar over 6-36 months. Associations of postural measures with fall rates were determined using negative binomial regressions. After covariate adjustments, postural stiffness (p=0.02-0.05) and damping (p=0.007-0.1) were associated with lower outdoor falls risk, but not with indoor falls. Results were invariant by direction (anteroposterior versus mediolateral) or by condition (quiet standing versus dual task). Outdoor fall risk may be tied to postural control more so than indoor falls. Dual tasking is likely related to fall risk among older and sicker older adults, but not those relatively healthy.

The Non-linear Relationship between Gait Speed and Falls: The MOBILIZE Boston Study

OBJECTIVES: To examine the relationship between gait speed and falls risk.

Indoor and Outdoor Falls in Older Adults are Different: The MOBILIZE Boston Study

OBJECTIVES: To identify risk factors for indoor and outdoor falls.

Idiopathic Peripheral Neuropathy Increases Fall Risk in a Population-Based Cohort Study of Older Adults

Background Peripheral neuropathy (PN) is often associated with specific diseases; however, research suggests that idiopathic PN is prevalent in older adult populations [1]. Foot ulceration is the traditional medical concern with PN, but people with PN may also have disproportionately more falls [2]. Therefore, our objective was to evaluate associations between PN and prospectively-ascertained falls in older adults from the population-based MOBILIZE Boston Study.

The Relationship between Cognitive Impairment and Upper Extremity Function in Older Primary Care Patients

BACKGROUND Individuals with mild cognitive impairment (MCI), often a precursor to dementia, experience limitations in completing daily activities. These limitations are particularly important to understand, as they predict risk for dementia. Relations between functional changes and both cognitive decline and upper extremity motor impairments have been reported, but the contribution of motor function to relations between cognitive function and functional independence remains poorly understood. We examined the relationship between cognition and upper extremity activities, and whether this relation was mediated by motor function. METHODS A total of 430 community-dwelling primary care patients aged at least 65 years from the Boston Rehabilitative Impairment Study of the Elderly completed self-report measures of upper extremity function, tests of neuromuscular attributes to measure motor function (reaction time, pronosupination of the hands), and neuropsychological measures. Participants were classified based on cognitive performance into groups: MCI and without MCI, with MCI further classified by cognitive subtype. Regression and mediation analyses examined group differences and relations between cognitive function, upper extremity function, and neuromuscular attributes. RESULTS MCI participants demonstrated poorer neuromuscular attributes and self-reported upper extremity function, and neuromuscular attributes significantly mediated positive relations between cognitive status and self-reported upper extremity function. Poorer self-reported upper extremity function was most prominent for groups with executive dysfunction. CONCLUSIONS Together with previous research, results suggest that the relationship between cognitive function, motor function, and functional activities is not confined to mobility tasks but universally related to body systems and functional activities. These findings inform new approaches for dementia risk screening and rehabilitative care.