Journal of Geriatric Physical Therapy:
Fall Risk Assessment Among Older Adults With Mild Alzheimer Disease
Ryan, John J. PT, DHS1; McCloy, Constance PT, EdD2; Rundquist, Peter PT, PhD2; Srinivasan, Visalakshi MD1; Laird, Rosemary MD1
1Health First, Melbourne, Florida.
2University of Indianapolis, Indianapolis, Indiana.
Address correspondence to: John J. Ryan, PT, DHS, 2473 Empire Ave, Melbourne, FL 32934 (email@example.com).
Purpose: Older adults with Alzheimer disease (AD) fall more than twice as often as those without dementia, yet few studies have assessed fall risk in this population. The purpose of the study was to determine whether a fall assessment, the Physical Performance Test 7-item (PPT 7-item), could accurately identify subjects with history of falls in a group of community-dwelling elders with mild AD. An additional purpose was to determine whether the PPT 7-item, a cognitive screen, and/or nonperformance data could predict falling in this population.
Methods: Forty-three community-dwelling elders diagnosed with mild AD completed the fall risk assessment. In addition, the following data were collected: Mini-Mental State Examination (MMSE) score, age, gender, education, gait aid use, number of falls in the past 6 months, and history of fall-related injury.
Results: There was a significant difference in the PPT 7-item total score between subjects with history of falls and subjects without history of falls (z = −2.04, P = .042), with items related to turning (z = −2.56, P = .01) and walking (z = −2.89, P = .004) accounting for most of the difference. However, only gait aid usage predicted falling (45.8% of the variance).
Conclusion: While the PPT 7-item was able to detect differences in mobility between subjects with history of falls and subjects without history of falls in subjects with mild AD, total PPT 7-item score did not predict falling. Gait aid usage was more strongly related to falling in these subjects. Early detection of fall risk in individuals with mild AD is important to prevent injuries and moderate costs of care.
Approximately 30% of community-living older adults (≥65 years of age) in the United States fall each year, resulting in medical costs of more than $20 billion per year.1–3 Fall-related injuries are the fifth leading cause of death in older adults.1
Numerous tests and intervention programs have been researched to identify fall risk and to reduce falls and injuries in cognitively intact older adults.4–6 However, few studies have addressed fall risk screening in older adults with Alzheimer disease (AD).6–9 People with AD tend to fall more often and are more seriously injured from falls than cognitively intact older adults.7 The annual incidence rate for falling is 60% to 80% for older adults with AD, over twice the incidence of age-matched cognitively intact older adults.8–10 In addition, seniors with AD sustain nearly 3 times the number of fall-related fractures than those who have normal cognition.11–13
Research has focused on measurement of physical mobility in people with AD in the later stages of this disorder. Little is known about the impact AD has on physical function in the early stages of the disease (mild AD). Determining the mechanisms for why AD increases the risk of falling in older adults is complex and not fully understood. Suggested causes for falls in this population have included cognitive impairment, AD-associated changes in balance and gait, and other conditions that complicate AD such as impaired reaction time, side effects of commonly prescribed medications (eg, antidepressants, anxiolytics, antipsychotics), and risky behavior such as wandering.14
Identifying a reliable fall assessment tool for older adults with mild AD may help in the early detection of fall risk in this highly vulnerable group. In addition, few studies have explored the interactions among variables such as age, gender, education, gait aid, cognitive ability, functional mobility, and fall risk. Identifying fall risk early in the disease process may help to reduce morbidity and mortality and decrease the costs associated with falling.
PHYSIOLOGICAL AND COGNITIVE IMPLICATIONS IN ALZHEIMER DISEASE
Alzheimer disease currently affects 5.2 million Americans.15 It is a degenerative disorder of the brain's cytoskeleton, affecting multiple neuronal systems. Major hallmarks of this disease include intraneuronal neurofibrillary tangles and extracellular deposits (plaques) of the protein β-amyloid.16 For the past 2 decades, researchers thought AD primarily affected cognition early in the disease process and spared motor function until more advanced stages.17 However, recent work is beginning to challenge this notion.13,18 Walking is now viewed as a cognitive process requiring higher-level control, and researchers are now observing that changes in cognitive function associated with AD contribute to gait disturbances and increase fall risk in individuals with this disorder.13
A number of physiological and cognitive changes associated withAD affect functional mobility. In AD, executive dysfunction and loss of attention control are considered pervasive.13 Executive function is synonymous with cognitive control, the brain processes that guide thought and behavior in accordance with internally generated goals or plans.19 Impairments in attention can hinder information processing at multiple levels within the brain, and may explain aspects of functional decline in aging and dementia.20,21 Current evidence suggests that after an initial stage of amnesia, attention is the first nonmemory domain to be affected by AD, before deficits in language and visuospatial functions.13,21,22 Difficulties with activities of daily living, which occur in even mildly demented patients, may be related to attention deficits.22,23 Furthermore, the chance of falling may increase because of an inability to adapt to unpredictable sensory input. If tasks become too complex, capacity overload occurs, and performance may suffer.
Alzheimer disease is associated with impaired sensori-motor processing, visuospatial disorientation, and difficulty in suppressing visual distraction.10,12 Chong et al10 compared the balance performance of subjects with AD on the Sensory Organization Test with healthy aged-matched individuals and subjects with Parkinson's disease. The Sensory Organization Test assesses the subject's ability to maintain standing balance under combinations of normal, absent, and/or incongruent visual, vestibular, and somatosensory conditions. To maintain balance, subjects must suppress the incongruent signals, while simultaneously using the congruent ones. The subjects wore a harness suspended from the ceiling during testing. The harness allowed free body movements but prevented the subjects from contacting the floor in the event of a complete loss of balance. A fall was identified when a subject fell into the harness or took a step. Despite having normal vestibular system function, the subjects with AD fell more often than those in the other 2 groups and did not demonstrate improvement with repetitions. Subjects with AD fell frequently when vestibular information was essential for orientation perhaps because they were unable to suppress incongruent visual and somatosensory information.10
AGE, FALLS, AND ALZHEIMER DISEASE
Normal aging inevitably brings physical and cognitive changes that may contribute to the risk of falls, including sensory, musculoskeletal, neurological, and metabolic changes. Seniors older than 80 years are the most likely to fall and be injured.24 However, it is not age per se that increases the risk of falls; multiple comorbidities associated with aging greatly enhance fall risk. Age and AD also go hand in hand. According to the National Institute on Aging,25 age is the most important known risk factor for AD. A study by Bassiony et al26 supported this trend. In their study of falls and age in community-dwelling elders with AD, they reported that falls were associated with older age, after controlling for multiple other factors.
THE EFFECTS OF EDUCATION ON FALLS IN INDIVIDUALS WITH ALZHEIMER DISEASE
Ott et al27 identified an inverse relationship between education and the development of dementia. In addition, studies have shown that having more years of education may delay the onset of clinical symptoms of AD.28,29 Investigators have postulated that older adults with AD who have more education may have a higher level of neural reserve and neural networking, which in some way may delay neurodegeneration.30 Thus, as AD progresses and neurons die, others neurons may carry out similar functional tasks, reducing some signs of functional and cognitive impairment.31
Bennett et al32 also provided strong evidence that level of formal education provides some type of cognitive or neural reserve that reduces the deleterious effect of senile plaques on cognitive abilities. They suggested that education provides a cognitive advantage; persons with more years of education have higher levels of cognitive function throughout adult life and therefore require more pathology to reach any given level of cognitive impairment.
FUNCTIONAL MOBILITY AND FALLS IN INDIVIDUALS WITH ALZHEIMER DISEASE
Although walking may be considered an “automatic” activity, it may require greater attention and executive function if there is a sudden change in the walking surface, or if it involves multitasking, such as carrying an item or using an assistive device when walking. Normal aging involves changes in the primary sensory areas (eg, vision, hearing, vestibular, somatosensory). Thus, more cognitive effort may be required to accommodate for these systemic changes.9,12 Progressive decline in cognitive function, as observed in individuals with AD, may lead to disorganization of the network that controls locomotion, leading to impaired gait speed, timing, and poor postural control.13
O'Keeffe et al33 have stated that gait abnormalities can exist even in individuals with mild AD and that a “cautious gait” is the most common gait abnormality in these patients. A cautious gait is a mode of ambulation that is associated with real or perceived instability.34 This appears similar to the fear of falling experienced by some older adults and may lead to deconditioning and further risk of falling.35,36 Fear of falling has been shown to cause spatial and temporal gait parameter changes in normal older adults. Examples of gait parameter changes include slower gait speed, shorter stride length, increased stride width, and prolonged double limb support time. Gait changes such as these are more common in subjects with history of falls compared with subjects without history of falls. A number of studies have concluded that stride length variability in the adult population with mild to moderate AD leads to instability and is a main contributor to the increased incidence of falls in this population.7,13,36
In studies focused upon dual-task performance, individuals with AD performed like controls when 2 tasks were attempted separately but showed a disproportionate decline in performance when the tasks were performed concurrently.13,37 Impaired dual-task performance during walking has been identified as one reason why persons with AD fall in some circumstances.23,38,39 For example, Camicioli et al38 compared community dwelling healthy young old (mean age, 72 years) with healthy older old adults (mean age, 86 years) and adults with probable AD (mean age, 74 years) in the performance of a dual task. Subjects were asked to walk down a hallway 15 ft and back at a brisk but comfortable pace while reciting different male names aloud. Subjects with AD walked significantly slower than the other 2 groups. The difference in walking speed between the 2 groups without AD was not significant. The authors concluded that the tendency of individuals with AD to perform poorly during dual tasks involving gait was consistent with higher risk of injuries and falls than that observed in the other elder groups.
Gait speed has been shown to be an important predictor of disability.40 Moreover, gait speed is related to cognitive and executive function in nondemented older persons.41,42 Gait speed of 0.6 m/s or less has been associated with an increased likelihood of falling among cognitively intact older adults.13,43–45 Seniors with AD tend to walk even slower than adults without AD, placing them at greater risk for falls.7 Indeed, research has demonstrated that slow gait speed has been associated with increased fall risk among older adults with AD.13,45,46 Studies have also shown that patterns of walking (ie, step length) in persons with AD were different from those of age-matched, cognitively intact elders.33,47 Wang et al48 suggested that gait slowing and poor balance might even be early markers for the onset of AD in seniors.
THE EFFECTS OF GAIT AID USAGE ON FALLS IN INDIVIDUALS WITH ALZHEIMER DISEASE
Assistive devices, such as canes and walkers, used to aid gait can improve balance control by providing mechanical advantages as well as somatosensory feedback.49 Gait aids can also increase older adults' confidence and feelings of safety, which, in turn, can increase their levels of activity and independence.50,51 However, some research indicates that gait aid usage has been significantly associated with falls and injuries.44,52 There are several attentional, neuromotor, musculoskeletal, physiologic, and metabolic demands associated with using gait devices, and several potential mechanisms by which they may adversely affect balance control. Inappropriate device prescription, inadequate user training, or use of unprescribed devices may also exacerbate fall risk.53,54
Some experts have suggested that use of a gait aid may simply be an indicator of balance impairment, functional decline, and/or falling risk.55 Others have argued that use of gait device may actually increase risk of falling by causing tripping or by disrupting balance control.56,57 Older adults, in particular, appear to experience reduction in postural stability while engaging in activities that compete for available attentional and cognitive resources (dual task performance).58 One author suggested that increased attentional demands could lead to tripping and loss of balance by affecting one's ability to avoid obstacles or hazards in the environment.49
Carter et al52 reported that community dwelling, cognitively intact, older adults who used a gait aid were 3.4 times more likely to fall than those who did not. In their study of community-dwelling elders, Murray et al44 found that 80% of subjects with a fall history in the prior 12 months used a gait aid.
Considering the cognitive and functional deficits that are unique to the older adult with mild AD, it is important to identify whether gait aids are associated with falling in this population of older adults. The attention deficits, impaired dual task performance, and visuospatial skills that largely impact gait performance in older adults with mild AD may further complicate safe mobility by interfering with correct gait sequencing using a gait aid.13,38,59 Additional research is needed to determine whether gait aids are related to fall risk in individuals with AD.
PURPOSE OF THE STUDY
The purpose of this study was to determine whether a fall assessment, the Physical Performance Test 7-item (PPT 7-item), performed by a physical therapist could accurately identify subjects with history of falls in a group of community-dwelling elders with mild AD. An additional purpose of the study was to determine whether age, gender, education, gait aid usage, cognitive screen, and PPT 7-item could predict falling in this sample.
1. Is the PPT 7-item score different among subjects with history of falls and subjects without history of falls in a sample of persons with mild AD?
2. What are the relationships between age, gender, level of education, gait aid usage, cognitive status, PPT 7-item score, and fall status in a sample of persons with mild AD?
3. Are age, gender, level of education, gait aid usage, cognitive status, and the PPT 7-item score useful in predicting fall status?
Potential subjects were recruited from community living, independently ambulatory persons with diagnosis of mild AD followed at the Health First Aging Institute in Melbourne, Florida. The diagnosis of “mild” AD was a clinician judgment made by the geriatrician on the basis of an individual's history and their impairment in function. Signs of mild AD include the folllowing: (1) consistent memory problems that are more marked for recent events, (2) difficulties that interferes with everyday activities, (3) moderate difficulty with time relationships, (4) moderate difficulty in handling problems with social judgment usually maintained, (5) inability to independently function in community affairs, (6) mild but definite impairment of function at home, (7) abandonment of difficult chores, (8) abandonment of complicated hobbies, and (9) the need for prompting for personal care.60
Subjects interested in participating were examined by a geriatrician to determine eligibility. Those subjects with neurological, cardiopulmonary, or orthopedic impairments judged unable or unsafe in completing the planned tested were excluded. Subjects deemed eligible to participate received a brief explanation of the study from the physician. Those interested in participating were contacted by the researcher who provided detailed information and answered questions from subjects and their legally authorized representatives (LAR) about participation in the study. Following this, subjects were given appointments to complete enrollment, provide written informed consent, and begin testing. All testing occurred between November 2007 and June 2008. A total of 59 subjects expressed interest; 43 enrolled and completed testing. Institutional review board approval was obtained before initiating the study procedure.
Three types of data were collected: demographic information, cognitive status (MMSE [Mini-Mental State Examination] score), and fall risk (PPT 7-item).
Once informed consent was obtained, each subject was asked to provide the following information about themselves: age, gender, highest education level achieved, use of a gait aid, any history of fall(s) in the past 6 months including the number of falls, and if any medical attention was required because of a fall incident. A fall was defined as an unexpected event in which the subjects came to rest on the ground, floor, or lower level.61 Because some of the questions were dependent on recall, all responses were verified with the LAR.
The MMSE is a brief instrument used to screen for cognitive dysfunction, assess the severity of impairment, and document cognitive changes over time.62,63 The MMSE has become the most commonly applied cognitive test, used by approximately 9 of the 10 specialists.64,65 The MMSE includes 11 questions in 6 sections, each representing a different cognitive domain or function (orientation, registration, attention and calculation, recall, language, and copying).62 The maximum score on this test is 30. At a cut score of 24 or less, the MMSE has sensitivity of 87% and specificity of 82% for cognitive impairment.66
The MMSE is a valid and reliable instrument widely used to screen for cognitive impairment in older adults.62,67 Concurrent validity was determined by correlating MMSE scores with the Wechsler Adult Intelligence Scale (r = 0.90 P = .01), the Verbal IQ (r = 0.78, P < .0001), and Performance IQ (0.66, P < .001) tests.62 Test-retest reliability was assessed over a 24-hour period with 1 tester (r = 0.887, P < .0001), a 24-hour period with 2 testers (r = 0.827, P < .0001), and 28-day period with 2 testers (r = 0.988, P < .0001).62 The Pearson correlation for a 24-hour test-retest using 2 examiners was 0.827, indicating adequate interrater reliability.62 In the current study, the most current MMSE score for each subject was obtained from the geriatrician who made the diagnosis of AD.
The PPT was initially developed to assess multiple domains of physical function using observed performance of tasks that simulate activities of daily living of various degrees of difficulty.68–70 The dimensions assessed by the PPT include fine motor control, upper extremity gross motor function, balance, mobility, coordination, and endurance.69 The PPT has also been used to analyze fall risk among community dwelling older adults without dementia.71,72 Mean values for PPT-7 reported in the literature range from 11.8 to 18.3 for elders who are frail, from 18.8 to 24.4 for community-living elders, and from 19.6 to 21.3 for persons with AD.69,72–76
Several researchers have used the PPT 7-item as a fall assessment tool for cognitively intact older adults. VanSwearingen et al72 used the PPT 7-item to identify frail older adults (mean age, 75.5 years) who were at risk for recurrent falls (n = 84) (sensitivity = 78%; specificity = 71%; cutoff score = 15). Delbaere et al71 identified through logistic regression analysis that the best physical predictor of a fall among a group of community-dwelling older adults without dementia was a low score (≤18/28) on the PPT 7-item (OR = 4.16, P < .001).
The PPT 7-tem has been found to be a more sensitive measure of early or mild functional decline than more traditional activities of daily living scales for older adults with both normal cognition and dementia.73,77 The PPT 7-item has been shown to demonstrate internal consistency (Cronbach α = 0.79) and interrater reliability (Pearson r = 0.93) among normal older adults and those with dementia.69,78 The PPT 7-item has also demonstrated concurrent validity with other functional status assessments, namely the modified Rosow-Breslau (0.69),79 the Katz Activities of Daily Living scale (0.50),80 and the Spector Hierarchical Relationship Between Activities of Daily Living and Instrumental Activities of Daily Living Scale (0.56).81 Although the validity of PPT 7-item as a measure of fall risk in a population of older adults with dementia has not been evaluated, the PPT 7-item has been found useful in identifying older adults without dementia at risk for falling.71,72,82
Individual tests and scoring for the PPT 7-item followed the protocol described by Reuben and Siu.69 All subjects in the current study were able to complete all aspects of the PPT 7-item, with 1 exception. One 85-year-old woman could not lift the heavy book to a shelf above shoulder height as she felt it was too heavy. Otherwise, no subject or LAR asked to stop the procedure before its completion. The PPT 7-item took no more than 15 minutes to administer in any instance.
The Statistical Package for the Social Sciences (SPSS version 16.0; SPSS Inc, Chicago, Illinois) was used for data analysis. Subjects were dichotomized by fall history into 2 groups: subjects with history of falls and subjects without history of falls. All continuous data was examined for normality using Shapiro-Wilk (W) statistic. Differences between groups were analyzed using independent t test or Mann-Whitney U test as appropriate. Relationships among variables were determined by rank biserial correlation (nonnormally distributed continuous variables) or phi correlation (dichotomous variables). Forward and backward stepwise regression with standard residuals and Cooks distance was used to determine which variables best predicted fall status. All analyses were repeated on the basis of differences between groups on individual PPT-7 items to determine whether individual items could predict fall status better than overall score. An overall alpha was set at ≤.05.
Characteristics of subjects with history of falls versus subjects without history of falls for age, education, gender, gait aid usage, and medical attention history are reported in Table 1. Of the 59 individuals invited to participate, 43 agreed to be tested. The remaining 16 either refused or were unreachable after the initial invitation to participate. Thirteen of the 43 subjects (30%) had fallen in the prior 6 months; 4 of these reported multiple falls. Subjects with history of falls had a median score of 18/28 on the PPT 7-item, and 24/30 on the MMSE, whereas the median PPT 7-item for subjects without history of falls was 22/28 and 23/30 on the MMSE (Table 2).
Age was the only variable that met parametric assumptions. There was no difference between groups with respect to age (W = 0.960, P = .144). Mann-Whitney tests identified no difference between groups in terms of level of education (z = −0.134, P = .907), gender (z = −0.163, P = .907), or cognitive status (z = −0.146, P = .886). The PPT 7-item scores of subjects with history of falls were significantly lower than those of subjects without history of falls (z = −2.035, P = .042). PPT 7-item was the only continuous variable found to be significantly correlated with fall history (r = −0.314, P = .040). Only gait aid was found to be significantly correlated with fall history among the dichotomous variables (r = 0.612, P < .001).83
Although the PPT 7-item and the gait aid usage were the only variables found to significantly correlate with the history of falling, all the variables were entered into the logistic regression analysis. There has been no research regarding the influence of gender, education, and gait aid usage on falling among older adults with mild AD. Therefore, these variables were included in the logistic regression analysis (along with age, PPT 7-item score, and gait aid usage) to identify the influence they may have had on identifying fall history in the study population. Forward stepwise logistic regression results indicated that gait aid usage was the only variable that explained a statistically significant amount of the variability in the history of having a fall. There were no outliers in this model, as indicated by standardized residual (ZResid) scores from −0.48305 to 2.07020, and the Cook distance (D) scores from 0 to 0.11905. The use of a gait aid correctly identified 100% of the subjects without history of falls, and 46.2% of the subjects with history of falls, and explained 45.8% of the variance in fall history data. A backward stepwise logistic regression was calculated to see whether any of the other independent variables contributed to the model. In this analysis, all the variables were removed except gait aid, again the only variable to explain a statistically significant amount of the variability in the history of having a fall.
Because the PPT 7-item was one of the last variables eliminated from the backward stepwise logistic regression and was the primary variable under analysis in this study, the logistic regression analysis was reevaluated including age, education, gender, PPT 7-item, and MMSE but excluding gait aid. Forward stepwise logistic regression analysis indicated that in this analysis the PPT 7-item was the only variable to explain a statistically significant amount of the variability in the history of having a fall. The Hosmer-Lemeshow test for goodness of fit (χ2 = 10.325, df = 7, P = .171) rejected the null hypothesis, indicating this model fit the data. Standardized residuals (ZResid) ranged from −0.32206 to 3.10499, with only 2 outliers of the 43 subjects (2.50828, 3.10499). On the other hand, the Cook distance (D) ranged from 0.00696 to 0.49084, acceptable results. The PPT 7-item correctly identified 96.7% of the subjects without history of falls, and 30.8% of the subjects with history of falls and explained 18.6% of the variance in the data. A backward stepwise method was then used to see how much the other variables might have contributed to this model. Once again, all the variables (age, gender, education, and MMSE) were removed other than the one best predictor, PPT 7-item.
Although not a part of the original set of research questions, the researchers were interested in identifying which of the individual tests on the PPT 7-item explained the greatest amount of variance in the data (excluding gait aid usage). An analysis of difference using Mann-Whitney U test was then conducted for the individual item tests within the PPT 7-item assessment tool. This analysis revealed that there was a significant difference between subjects with history of falls and subjects without history of falls with regard to the items N6 (z = −2.56, P = .01) and N7 (z = −2.89, P = .004). These 2 items were also significantly correlated with fall history: N6 significance (r = −0.396, P = .009); and N7 significance (r = −0.447, P = .003). Item N6 requires the subject to turn 360º, while item N7 requires the subject to walk for 25 ft, turn around, and walk back the 25 ft. Forward stepwise logistic regression analysis indicated that only item N7 explained a statistically significant amount of the variability in fall history data. Again, the Hosmer-Lemeshow goodness of fit test (χ2 = 2.941, df = 2, P = .230) rejected the null hypothesis. The standardized residuals test (ZResid), ranged from −0.53854 to 3.63195, identified only 1 outlier of the 43 subjects (3.63195). The Cook's distance (D) test, ranged from 0.00292 to 0.50837, indicated a good fit. The N7 variable correctly identified 83.3% of the subjects without history of falls, and 53.8% of the subjects with history of falls, and explained 32.5% of the variance in the data.
The purpose of this study was to determine whether a fall assessment, the PPT 7-item, performed by a physical therapist could accurate identify subjects with history of falls in a group of community-dwelling elders with mild AD. An additional purpose of the study was to determine whether age, gender, education, gait aid usage, cognitive screen, and PPT 7-item could predict falling in this sample.
Statistically significant differences were found between subjects with history of falls and subjects without history of falls for 2 independent variables: the PPT 7-item total score and the use of a gait aid. However, only the use of a gait aid was predictive for falling.
The median PPT 7-item score for subjects in this study with a history of falling was 18/28. Delbaere et al71 identified a score of 18/28 as predictive for falling in a group of 263 relatively younger (mean age, 72) community dwelling, cognitively normal older adults. VanSwearingen et al72 found an even lower cutoff score for fall risk on the PPT 7-item (15/28) in a group of 84 frail community-dwelling elders (mean age, 76).72 In the current study, 7 of the 13 subjects with history of falls and 8 of the 30 subjects without history of falls had a PPT 7-item score of less than or equal to 18/28. On the contrary, 4 of the 13 subjects with history of falls had a score of less than 15 compared to only 1 subject without history of falls. Therefore, a lower cutoff score on the PPT 7-item (ie, ≤15/28) may be a better indicator of whether a community dwelling senior with mild AD is likely to have a fall.
Slow walking speed, decreased physical activity, poor endurance, and weakness are considered criteria for frailty,84 and frailty has been linked to an increased fall risk in older adults, with and without dementia.85 The PPT 7-item assesses many of the domains of physical function that are relevant to frailty. We now know that older adults with AD exhibit far greater problems of imbalance, slowed walking speed, impaired dual task performance, and incoordination than do cognitively intact adults. This may explain why the subjects in this study who had a history of falling took longer to complete the individual item tests on the PPT 7-item. However, the PPT 7-item total score was not a predictor of fall risk, unlike the findings of VanSwearingen et al and Delbaere et al. One possible reason for this disparity in results was that these researchers used different independent variables. VanSwearingen et al used the Modified Gait Abnormality Rating Scale, stride length, and walking velocity, along with the PPT 7-item. Delbaere et al used numerous variables addressing multiple domains (eg, medical, psychological, sensory, posture, strength, along with the PPT).
So, is the PPT 7-item a good test for assessing fall risk among older adults with mild AD? The results of this study are mixed. Subjects with history of falls had significantly lower PPT 7-item total scores than subjects without history of falls; however, the PPT 7-item did not predict falling. The PPT 7-item and use of a gait aid were significantly correlated (r = −0.492, P = .001). Thus, the more powerful fall predictor, gait aid, may have overshadowed the contribution of the PPT 7-item. In light of this, regression analysis without gait aid showed that the PPT 7-item was indeed a significant, though smaller, predictor of falling. Further analysis, this time for the individual items on the PPT 7-item, demonstrated that N7 (walking 25 ft, turning around, walking back 25 ft) scores for subjects with history of falls and subjects without history of falls were significantly different and that N7 significantly predicted falling. Research has demonstrated that slowed gait speed has been related to falls in both cognitively intact and impaired seniors.7,35,38,45,86 More specifically, a gait speed of 0.6 m/s or less has been found consistent with falling.7,35,38,45 Six of the subjects with history of falls in the current investigation walked at a speed of 0.6 m/s or less; none of the subjects without history of falls walked this slowly. It may be possible that the seniors in this study with a history of falling walked slower because of difficultly in multiple domains, such as balance, attention, dual-task performance (eg, walking with a gait aid), and coordination. In the end, it appears that the most informative component of the PPT 7-item was the test of gait speed. Thus, gait speed should be recorded when assessing fall risk for older adults with mild AD, either as part of the PPT 7-item or as a single independent test.
In the current investigation, there was also a significant relationship between gait aid and history of falling. This was consistent with Carter et al52 who found that the use of a gait aid was associated with an increased risk of falling. The pathophysiology and cognitive changes associated with AD may help explain why use of a gait aid could increase the risk for falling in this subject group.13,14,16,21–23 Elders with mild AD exhibit impaired dual-task performance during walking, possibly making the use of a gait aid difficult. They may also have difficulty suppressing incongruent visual and somatosensory information. Frontal lobe dysfunction may cause disinhibition of behavior, poor judgment, and movement disorders.87 Seniors with mild AD may not adapt their mobility behavior to match their cognitive and physical impairments.87 Poor memory retention for instructions on the use of gait aid may also decrease safety.
The use of a gait aid can also be demanding on the individual with mild AD, sometimes more than they can cognitively or physically handle.44,50,52 Using a gait aid requires attention, one of the first perceptible deficits of AD. Neuromotor incoordination, imbalance, and faulty posture while using the gait aid may contribute to fall risk. Musculoskeletal complaints, such as weakness and pain, exacerbate the demands imposed by using a gait aid. The metabolic load (increased energy to manage the gait aid) may also compound the physiological demands of safe mobility with a gait aid. Inappropriately prescribed gait aids, or inadequate training with a gait device, may lessen the likelihood of compliance with a gait aid, and its safe usage. An older adult with mild AD who uses an unprescribed gait aid may increase their likelihood of falling. A poorly fitted gait aid, or one that is inadequate or faulty, may increase the possibility of tripping.
This study had several limitations that must be acknowledged. First, there was a lower than anticipated number of subjects for this study. Sixteen individuals selected for this study were unreachable after their physician visit. According to the geriatrician who diagnosed the subjects, it was difficult for some patients to arrange transportation to attend the study. Others were not interested in an additional medical office visit. The geriatrician reported that many of the subjects who did appear for the study were more mobile than nonparticipators and thus were more willing to be in the study. Therefore, this group of subjects may have been higher functioning and had fewer falls overall than an “average” group of individuals with mild AD. Finally, given the memory problems associated with even mild AD, subjects with history of falls may have underreported their number of falls, or subjects without history of falls may have not recalled the occurrence of a fall in the past 6 months. An effort was made to gather accurate fall history information by confirming subject responses with the LAR. However, it was possible that some falls occurred without the knowledge of the LAR.
Research typically excludes subjects with dementia, a highly vulnerable population of adults. Seniors with mild AD are more likely to fall because of a number of factors. Early recognition is imperative, as we now know that physical changes occur early in the course of this disease alongside the cognitive changes. Reliable, valid, and quick fall screens can provide effective early identification of individuals at risk for falls. An additional assessment of gait speed could help to identify seniors with mild AD who may fall. Finally, physical therapists and other health care providers who issue gait aids should do so carefully, assessing the ability of elders to physically and cognitively use these assistive devices safely.
Future research should include a larger sample size, using random selection. The PPT 7-item should be validated with regard to assessing fall risk in elders with AD with other prevailing fall risk assessments.
Much gratitude is extended to the administration and employees at Health First in Melbourne, Florida, for all their support in making this project possible. Special recognition goes to Jennifer Paranhos, MSW, for her assistance in recruiting study participants, and to William Hanney, DPT, ATC/L, for providing his expertise and resources in helping me complete this study.
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accidental falls; Alzheimer disease; fall risk assessment; community-dwelling elders; physical therapy
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