Beyond Balance and Mobility, Contributions of Cognitive Function to Falls in Older Adults with Cardiovascular Disease
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Journal of Frailty, Sarcopenia and Falls Original Article Beyond balance and mobility, contributions of cognitive function to falls in older adults with cardiovascular disease Jennifer Blackwood1, Shweta Gore2 1Physical Therapy Department, University of Michigan-Flint, USA, 2MGH Institute of Health Professions, Boston, MA, USA All published work is licensed under Creative Common License CC BY-NC-SA 4.0 (Attribution-NonCommercial-ShareAlike) Abstract Objectives: Older adults with cardiovascular disease (CVD) are at risk for cognitive impairment. Cognitive function is associated with falls in older adults however it is unknown if a relationship exists between cognitive function and falls in CVD. The aim of this study was to examine the contributions of cognitive function on falls in older adults with CVD. Methods: A secondary analysis was performed on data from the Health and Retirement Study cohort 2010 (N=3413) of older adults with CVD. Group assignment was based on falls history (yes/no) within the two years prior to the survey. Demographic (age, education, gender, marital status), physical (strength, balance, physical activity, and mobility) and cognitive (immediate and delayed recall, orientation, semantic verbal fluency, numeracy) information was extracted to characterize the sample. Comparisons between groups were completed for all of these variables. Logistic regression was performed to examine associations between each of the cognitive variables and falls while controlling for age, gender, marital status, education, and BMI. Results: Demographic (age, gender, marital status, and education), physical (grip strength, tandem stance time, and gait speed), and cognitive (orientation, immediate and delayed recall) variables differed by falls history (p<0.05). After controlling for confounding, immediate recall was the only significant predictor of falls (OR=1.09, 95% CI=1.01-1.17) (Nagelkerke R2=0.037, χ2=35.14, p<0.05) with correctly classifying 65.9% of cases. Conclusions: In older adults with CVD, cognitive and physical functions are more impaired in those with a falls history. Screening for cognitive function, specifically immediate recall, should be a part of the management of falls in this population. Keywords: Cardiovascular disease, Cognition, Recall, Falls, Mobility Introduction Of particular interest is that despite the possibility of cognitive decline occurring throughout the aging process13, One out of four older adults falls each year, accounting the changes in cognition may be more pervasive in those for more than fifty billion dollars in health care costs1. with CVD14,15. The prevalence of cognitive impairments in Adults with cardiovascular disease (CVD) are reported to adults with CVD ranges from 30% to 80% and is dependent have higher odds of falling as compared to those without on disease type and duration16-20. However, decreased reported CVD2. A link between cognition and falls/falls performance on cognitive measures has been reported risk has been reported in the literature. Cognitive function in older adults with CVD regardless of age and education is used in everyday mobility tasks and specifically during goal-directed activities, the initiation of tasks, and while negotiating obstacles within the environment3-6. Older adults with impaired cognition have an increased likelihood The authors have no conflict of interest. of falling than cognitively intact peers, and are at an Corresponding author: Jennifer Blackwood PT, PhD, GCS, increased risk for an injurious fall, and institutionalization Physical Therapy Department, University of Michigan-Flint, 2157 William S. White Building, 303 East Kearsley Street, after falling7-11. Various cognitive processes have been Flint, MI 48502-1950 identified as significant predictors of functional decline and falls in older adults7-9. In older adults, impaired E-mail: [email protected] cognitive function has been associated with decreased Edited by: Dawn Skelton performance in activities of daily living12 and slower, more Accepted 22 August 2019 impaired gait4. http://www.jfsf.eu doi: 10.22540/JFSF-04-065 JFSF | September 2019 | Vol. 4, No. 3 | 65-70 65 J. Blackwood, S. Gore indicating that cognitive dysfunction may play a more Demographic data extracted included age, gender, predominant role in those with CVD16. marital status, and education. Other health related variables Studies in CVD which address falls risk factors have included the reported frequency of engaging in mild physical primarily focused either on mobility related factors such activity at least once per week and anthropometric measures as decreased gait speed, impaired balance or the presence for calculation of body mass index (kg/m2). Falls information of disease associated side effects (e.g. orthostatic required respondents or their proxy to account for any falls hypotension)2,21. Although changes in functional mobility which occurred in the two years prior to the survey interview. provide sufficient evidence of the concern of falls in CVD, Falls data extracted included incidence (yes/no), number of a crucial knowledge gap exists in the additional role that falls, and whether an injury (yes/no) had occurred from a fall. cognitive impairment plays on falls, given the prevalence of Measures of strength, balance, and mobility were extracted cognitive decline in older adults with CVD. Determination of to characterize the sample. Grip strength measurement data the specific cognitive functions that contribute to falls in older (dominant hand) was used as a measure of overall strength. adults with CVD is imperative to incorporate appropriate Tandem stance time was used as a measure of balance. cognitive screening and interventions in this population for Considered to be a necessary component of balance in reducing falls risk. Therefore, the aim of this study was to community dwelling older adults, the ability to perform first describe the differences in cognitive function in older tandem stance has been associated with fall risk24. The total adults with CVD by falls history. A secondary aim was to amount of time, in seconds that the respondent was able to examine the influence of specific cognitive processes on falls stand in heel to toe tandem position without support for up (yes/no) in older adults with CVD using logistic regression. to 60 seconds was recorded. Mobility was assessed via gait speed measurement. Gait speed is associated with cognitive Materials and methods function and falls in older adults25. In the HRS, gait speed was The sample for this cross-sectional study comes from measured over two trials as the time (in seconds) required the 2010 wave of the Health and Retirement Study (HRS). to walk an eight-foot distance on level surfaces. The average HRS is a longitudinal study which surveys a representative speed over two trials was calculated and converted to meters sample of approximately 20,000 community dwelling per second for analyses. Americans over age 50 every two years22. The 2010 wave Cognitive data extracted included assessments of memory included participants from 50- 110 years of age. A detailed (immediate and delayed), orientation, verbal fluency, and description of the study can be found at: http://hrsonline.isr. numeracy. Memory was measured via immediate and delayed umich.edu/. This secondary analysis was approved by the word recall. For immediate word recall (IWR), the interviewer institutional review board of the primary investigator. read a randomly assigned list of 10 nouns to the respondent, Data for the HRS interview was collected between March and asked the respondent to recall as many words as 2010 through May 2011 through information provided possible from the list in any order immediately afterwards. by the respondent or their proxy. Data was included if The number of correctly recalled words was recorded for respondents were aged 65 years+, had a diagnosis of CVD, this task. Delayed word recall (DWR) required respondents and did not have Alzheimer’s disease, dementia, diabetes, to name as many of those original 10 words after a period depression, or history of cancer. Additionally, those of 5 minutes had passed and during which the respondent with a history of stroke were excluded from the sample was engaged in other tasks. DWR was scored in the same to reduce confounding of falls and associated cognitive fashion as IWR. Orientation was assessed by the respondent impairments resulting from cerebrovascular insults. The being able to correctly recall the week, month, day, and year. American Heart Association definition for CVD was used Scores ranged from ‘0’ indicating that no correct responses to create the sample population. CVD was defined as were provided to ‘4’ indicating that all orientation items any condition affecting the heart and blood vessels and were correctly answered. A verbal fluency task was used included diagnoses of coronary heart disease, congestive as a measure of executive function as it requires the use of heart failure, hypertension, peripheral artery disease, strategic search, set-shifting and semantic memory for task arrhythmia, or heart valve disorders23. Respondents completion26. In the semantic verbal fluency test respondents who reported to have a physician diagnosis of heart were required to name as many animals as possible in 60 disease, myocardial infarction, congestive heart failure, seconds with the total number of named animals to comprise arrhythmia, heart valve problems, hypertension, or those the score. Numeracy was measured