Stops walking when talking a predictor of falls in older adults

European Journal of Neurology 2009, 16: 786–795 doi:10.1111/j.1468-1331.2009.02612.x REVIEW ARTICLE Stops walking when talking: a predictor of falls in older adults? O Beaucheta, C Annweilera, V Dubostb, G Allalic, R W Kressigd, S Bridenbaughd, G Berrute, F Assalc and F R Herrmannf a Department of Geriatrics & Faculty of Medicine, Angers University Hospital and University of Angers, UNAM, France; bFormadep, Korian, Paris, France; cDepartment of Neurology & Faculty of Medicine, Geneva University Hospitals, Switzerland; dDepartment of Geriatrics, University of Basel & Basel University Hospital, Switzerland; eDepartment of Geriatrics & Faculty of Medicine, Nantes University Hospital & University of Nantes, UNAM, France; and fDepartment of Rehabilitation and Geriatrics & Faculty of Medicine, Geneva University Hospitals and University of Geneva, Switzerland Keywords: dual-task-related gait changes, falling, gait, older adult Received 29 July 2008 Accepted 18 February 2009 The objective of this study was to systematically review all published articles examining the relationship between the occurrence of falls and changes in gait and attention-demanding task performance whilst dual tasking amongst older adults An English and French Medline and Cochrane library search ranging from 1997 to 2008 indexed under Ôaccidental fallsÕ, Ôaged OR aged, 80 and overÕ, Ôdual taskÕ, Ôdual taskingÕ, ÔgaitÕ, ÔwalkingÕ, ÔfallÕ and ÔfallingÕ was performed Of 121 selected studies, fifteen met the selection criteria and were included in the final analysis The fall rate ranged from 11.1% to 50.0% in retrospective studies and from 21.3% to 42.3% in prospective ones Amongst the three retrospective and eight prospective studies, two and six studies, respectively, showed a significant relationship between changes in gait performance under dual task and history of falls The predictive value for falling was particularly efficient amongst frail older adults compared with healthy subjects Two prospective studies challenged the usefulness of the dual-task paradigm as a significant predictor compared to single task performance and three studies even reported that gait changes whilst dual tasking did not predict falls The pooled odds ratio for falling was 5.3 (95% CI, 3.1–9.1) when subjects had changes in gait or attention-demanding task performance whilst dual tasking Despite conflicting early reports, changes in performance whilst dual tasking were significantly associated with an increased risk for falling amongst older adults and frail older adults in particular Description of health status, standardization of test methodology, increase of sample size and longer follow-up intervals will certainly improve the predictive value of dual-task-based fall risk assessment tests Introduction Simple and efficient detection of fall risk in older adults is a major objective of geriatric medicine Twelve years ago, Lundin-Olsson et al [1] published a seminal paper that showed that Ôstops walking when talkingÕ could be a predictor of falls and thus introduced a new approach to fall prediction based on dual-task performance The principle of dual-task gait assessment is to compare task performance whilst walking and simoultaneously executing an attention-demanding task to performance of either one of single tasks [2,3] Changes Correspondence: Olivier Beauchet, MD, PhD, Department of Geriatrics, Angers University Hospital, 49933 Angers Cedex 9, France (tel.: ++33 41 35 45 50; fax: ++33 41 35 48 94; e-mail: olbeauchet@chu-angers.fr) 786 in performance whilst dual tasking are usually interpreted as interference because of competing demands for attentional resources needed for both tasks [3,4] and mainly depend on oneÕs capacity to properly allocate attention between the two tasks [2,3] Over the past years, dual-task-related gait changes have frequently been reported amongst older adults [4,5] However, published data are heterogeneous and show that impaired dual tasking is [1,6–14] and is not associated with falls [15–17], or is even an irrelevant fall risk indicator compared to impaired single task performance [6,18,19] Using a systematic review of the literature, we selected and analysed all published data, which examined the relationship between fall incidences and changes in gait and/or attention-demanding task performance whilst dual tasking amongst people aged 65 and older and identified the reasons of those conflicting results Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS Dual task and prediction of falls Methods Literature search An English and French Medline literature search of all articles published from March 1997 to April 2008 using the Medical Subject Heading (MeSH) terms Ôaccidental fallÕ and Ôaged or aged, 80 and overÕ combined with the terms Ôdual taskÕ, Ôdual taskingÕ, ÔgaitÕ, ÔwalkingÕ, ÔfallÕ and ÔfallingÕ was performed The search also included the Cochrane library and the references lists of the retrieved articles To ensure a comprehensive approach, additional key studies known to the authors that did not meet the search criteria were also included Study selection and analysis Abstract selection was based on the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) checklist that described items that should be included in reports of cohort studies [20] Abstracts identified with the literature search were independently evaluated by two reviewers For those abstracts, which fulfilled the inclusion criteria (observational studies, retrospective or prospective data collection of falls, number of falls and motor performance under single and dual task as outcomes), full articles were obtained for the final analysis Final selection criteria were applied when mean age of 65 and older was reached, gait performance under single and dual task were specified as outcome measures, and enrolment methods, exact procedures of dual tasking and discriminative or predictive values of falls provided The study selection is shown on a flow diagram (Fig 1) Twenty-eight of 121 identified abstracts were first identified after screening using initial inclusion criteria Thorough revision further excluded 13 studies because 787 balance task was used as the main outcome measure (n = 6) [21–26], mean age of the sample younger than 65 (n = 2) [27,28], the cognitive task not described (n = 1) [29] or no measures of the discriminative or predictive value for falls provided (n = 4) [30–33] The remaining 15 studies [1,6–19] were included in this review The association between dual-task-associated gait changes and falls was determined based on the predictive value for falling, the odds ratio (OR) for falls with a 95% confidence interval (CI) and the positive and negative predictive value (PPV and NPV) for falls along with sensitivity and specificity All parameters were calculated for each study using Dag-stat a spreadsheet for the calculation of comprehensive statistics for the assessment of diagnostic tests and inter-rater agreement that provides a comprehensive range of statistics for by tables [34] A metaanalysis was conducted using the STATA software version 10.1 (Stata Corp., College Station, TX, USA 2007) to compute pooled OR associated with the risk of falls according to the results from the dual-task procedure either from the exact number of events and non-events when available or to compute an estimated OR (ES) from the natural logarithm transformation of the OR and 95% CI As a result of statistically significant heterogeneity amongst the studies, the DerSimonian and Laird random effects method was used to estimate the pooled OR 95% CI for the ORs were computed with the Woolf method Results Table summarizes the 15 studies included in this review Number of participants ranged from 30 to 380 [6,18] Fall rates ranged from 11.1% to 50.0% in retrospective studies of fall collection [6,14,15] and from Initial references identified (n = 121) Abstracts rejected because did not meet the initial criteria selection (n = 70; Duplication [22], Interventional studies [10], No dual-task [7], Review [5], Fall not outcome [49]) Meet criteria and were requested (n = 28) Manuscripts rejected because did not meet the final criteria selection (n = 13; balance task as outcome [6], mean age under 65 [2], cognitive task not described [1], no measures for discriminative or predictive value for falls [4]) Figure Flow diagram of selection of studies Manuscripts accepted for final inclusion (n = 15) Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 Community-dwelling N = 95 (70 non-fallers and 25 fallers) 73.4 ± 1.7 yearsa Women only Community-dwelling N = 370 (37 recurrent fallers and 333 non-fallers or single fallers) 78 ± yearsa Studies with a prospective data collection of falls Lundin-Olsson et al., Senior housing facilities 1997 [1] N = 58 80.1 ± 6.1 yearsa Main comorbiditiesb [Dementia (n = 26), Depression (n = 25), Previous stroke (n = 20)] Lundin-Olsson et al., Senior housing facilities 1998 [7] N = 42 79.7 ± 6.1 yearsa Main comorbiditiesb [Dementia (n = 21), Depression (n = 18), Previous stroke (n = 14)] Lundin-Olsson Senior housing facilities et al., 2000 [8] N = 78 82 (66-99) yearsc Main comorbiditiesb [Dementia (n = 38), Depression (n = 35), Previous stroke (n = 25)] Faulkner et al., 2007 [14] Vaillant et al., 2006 [15] Studies with a retrospective data collection of falls Shumway-Cook Community-dwelling et al., 2000 [6] N = 30 (15 non-fallers and 15 fallers) 78 ± yearsa for non-fallers and 86.2 ± for fallers Participant Conversation To carry a glass of water To carry a glass of water Conversation TUG Normal pace TUG Walking from home to an assessment room Normal pace Visuo-spatial decision task Arithmetic task (counting backward by 2, and 5) Cognitive task: Arithmetic task (counting backward by 3) Manual task: To carry a glass of water Attention-demanding task Walking from home to an assessment room Normal pace Straight walk (20 m course) and turn walk (20 m course with a turn at 10 m) Normal pace TUG Normal pace TUG Normal pace Walking task Dual task Table Summary of main characteristics of the studies included in the systematic review First fall indoors Difference between single and dual task ‡4.5 s (DiffTUG manual) months 13 (31.0) First fall indoors Stop walking Difference between single and dual task ‡4.5 s (DiffTUG manual) months 33 (42.3) First fall indoors Stops walking months 21 (36.2) Recurrent falls (‡2) Walking time (s) 12 months 37 (11.1) ‡1 falls Walking time (s) 12 months 25 (26.3) Recurrent falls (‡2) Walking time (s) months 15 (50.0) Outcomes Follow-up period Fall rate, n (%) Yes 28/33 37/45 28/36 37/42 (84.9)e (82.2)e (77.8)e (88.1)e Yes Yes (47.6) (94.6) (83.3) (76.1) Yes No Yes Were dual-task-related changes associated with falls? 7/13 (53.9) 26/29 (89.7) 7/10 (70.0) 26/32 (81.3) 10/21 35/37 10/12 35/46 Data not available Similar results for cognitive and manual task: 12/15 (80.0) 14/15 (93.3) 12/13 (92.3) 14/17 (82.4) Data not available Sensitivity Specificity Positive predictive value Negative predictive value n/n (%) 788 O Beauchet et al Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 Community-dwelling N = 311 >70 yearsd Community-dwelling and senior housing facilities N = 380 85 yearsd Main comorbiditiesb [Cognitive impairment (n = 40), Depressive symptoms (n = 80), Pain in lower limb (n = 195)] Inpatients with stroke N = 63 68.4 ± 10.6 yearsa Inpatients with stroke N = 159 74 (33-94) years Stalenhoef et al., 2002 [16] Bootsma-van Der Wiel et al., 2003 [18] Andersson et al 2006 [10] Hyndman et al., 2004 [17] Community-dwelling N = 60 79.6 ± 6.3 yearsa Main comorbiditiesb [Lower limb neuropathy (n = 12), Previous stroke (n = 2)] Participant Verghese et al., 2002 [9] Table (Continued) Walking from the assessment room to the lounge area (30-m) Straight walk TUG Normal pace Turn walk 12-m ([3-m, turn and 3-m return] x 2) As quickly as possible Straight walk (3-m) Normal pace 3-m (1.5-m, turn and 1.5-m return) Normal pace Walking task Dual task Conversation To carry a glass of water Conversation Reciting animals or profession names aloud Solve two simple calculations Reciting concecutively letters of the alphabet aloud (simple dual task) or alternatively (complex dual task) Attention-demanding task ‡1 falls Stop walking months 30 (47.6) First fall indoors Stop walking TUG difference between single and dual task (diffTUG) ‡4.5 s 12 months 68 (42.8) Recurrent falls (‡2) Abnormal score at dual task months 95 (30.5) ‡1 falls Stop walking 12 months 158 (41.6) First fall Score for simple dual task ‡ 20 s Score for complex dual task ‡ 33 s 12 months 13 (22.0) Outcomes Follow-up period Fall rate, n (%) 16/30 (53.3) 23/33 (69.7) 16/26 (61.5) 23/37 (62.2) Walking with conversation: 7/48 (14.6) 65/67 (97.0) 7/9 (77.8) 65/106 (61.3) Diff TUG manual: 5/29 (17.2) 56/59 (94.9) 5/8 (62.5) 56/80 (70.0) 71/158 (44.9) 121/222 (54.5) 71/172 (41.3) 121/208 (58.2) Simple dual task: 6/13 (46.2) 41/46 (89.1) 6/11(54.6) 41/48 (85.4) Complex dual task: 5/13 (38.5) 44/46 (95.7) 5/7 (71.4) 44/52 (84.6) Data not available Sensitivity Specificity Positive predictive value Negative predictive value n/n (%) No Yes No Yes No Yes Were dual-task-related changes associated with falls? Dual task and prediction of falls 789 Senior housing facilities N = 187 84.8 ± 5.2 yearsa Inpatients N = 57 85.0 ± 6.6 yearsa Senior housing facilties N = 213 84.4 ± 5.5 yearsa Beauchet et al., 2008b [19] Kressig et al., 2008 [12] Beauchet et al., 2008a [13] Backward counting aloud starting from 50 Straight walk (10-m) Normal pace Backward counting aloud starting from 50 Backward counting aloud starting from 50 Straight walk (10-m) Normal pace Straight walk (10-m) Normal pace Backward counting aloud starting from 50 Attention-demanding task Straight walk (10-m) Normal pace Walking task Dual task First Fall Increase backward counting performance 12 months 54 (28.9) First Fall Increase walking time whilst dual tasking >19.6 s 12 months 54 (28.9) First Fall Coefficient of variation of stride time variability whilst dual tasking >10% 50 days 10 (21.3) Recurrent fall (‡2 falls) Decrease in walking speed whilst dual tasking under the lowest tertile 12 months 57 (26.8) Outcomes Follow-up period Fall rate, n (%) Yes Yes 12/72 (16.7) 133/141 (94.3) 12/20 (60.0) 133/193 (69.9) Yes Yes Were dual-task-related changes associated with falls? 7/10 (70.0) 41/47 (87.2) 7/13 (53.9) 41/44 (93.2) 35/54 (64.8) 76/133 (57.1) 35/92 (38.0) 76/95 (80.0) 45/52 (86.5) 117/130 (90.0) 46/54 (85.2) 120/133 (90.2) Sensitivity Specificity Positive predictive value Negative predictive value n/n (%) M, Meter; TUG, Timed Up & Go; aMean ± standard deviation; bMain comorbidities reported; cMedian (range); dAge at inclusion; eCombined results of both dual tasks which were performed separately Senior housing facilities N = 187 84.8 ± 5.2 yearsa Participant Beauchet et al., 2007 [11] Table (Continued) 790 O Beauchet et al Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 Dual task and prediction of falls 21.3% to 42.3% in those with prospective ones [1,7– 13,16–19] Periods of fall collection ranged from to 12 months [1,6–19] Six studies examined frail older subjects living in senior housing facilities [1,7,8,11,13,19] Six other studies examined healthy community-dwelling older adults [6,9,14–16,18] and three studies focused on inpatients [10,12,17] Ten studies explored association between dual-task-related changes with the first fall event [1,7–12,15,17,19] and four with recurrent falls [6,13,14,16], defined as ‡2 falls during the follow-up period The type of attention-demanding task substantially differed amongst studies, whereas 11 of them used a conversation [1,8,10,17], an enumeration of the alphabet [9] or backward counting [6,11–13,15,19] that corresponded to a spoken verbal task; four studies used a manual task [6–8,10], one a visuo-spatial decision task [14] and one a combination of both attention-demanding tasks [8] Normal paced gait was measured in all studies [1,6–19] except one study [18] in which subjects walked as quickly as possible A straight walkway was used in all, but three studies in which a turn around and return route was used [9,14,18] The occurrence of falls was significantly associated with dual-task-related performance in 11 studies [1,614;19] The highest odds ratio for falling was 56.0 [6] and the lowest was 1.34 [14] Of the studies with prospective data collection of falls, six [1,7–9,12] reported that dual-task-related gait changes predicted falls with specificity ranging from 82.2% to 95.7% but with sensitivity between 38.5% and 84.9% Furthermore, both PPV and NPV were above 70% in all but two studies, which reported a PPV under 55% [9,12] Prediction of falls was based on gait changes in five studies [1,7– 10,12,13,19] and on attention-demanding task changes in one study [11] This last study showed the highest sensitivity, specificity, PPV, NPV and OR of all other studies with prospective data collection of falls (adjusted OR = 53.3, P < 0.001) In addition, two studies challenged the usefulness of the dual-task paradigm as a predictor of falls compared to single task performance [18,19] Although an increase in walking time whilst dual tasking was significantly associated with the occurrence of falls (respectively, OR 2.5 [1.3;4.7] and OR 3.3 [1.3;8.6]), the dual-task paradigm did not bring any additional information compared to the ambulation time under single task, i.e walking alone [18,19] Three studies did not find that changes in gait whilst performing a cognitive task might predict falls [10,16,17] Inpatients with stroke had changes in gait during a conversation [17] or whilst carrying a glass of water [10], yet these changes were not associated with falls The used dual-task score based on three levels (normal, doubtful and abnormal) was not associated with falls in StalenhoefÕs study [16] 791 Figure shows the specific OR and the pooled OR computed with meta-analysis technique Two studies were not included in this analysis because of lack of data [15,16] The pooled odds ratio for falling was 1.62 (95% CI, 0.96–2.72) for retrospectives studies and 6.84 (95% CI, 3.06–15.28) for prospective studies, when subjects had changes in gait or attention-demanding task performance whilst dual tasking The pooled odds ratio for falling when analysis included all studies was 5.3 (95% CI, 3.1–9.1) Discussion Divergent findings on dual-task-related gait changes, their relationship with falls and their usefulness for fall prediction raise a number of issues They mainly concern the methodology, demographics and/or sample recruitment (institutionalized versus community-dwelling older adults, differences in health status) and lack of consensus concerning dual-task paradigms From a methodological point of view, no information about the number of subjects required to predict falls was reported and studies did not include a post-hoc power analysis As a consequence, equivocal or negative results could be the result of a lack of power [11– 15] Furthermore, follow-up periods ranged from to 12 months Such short follow-up periods may underestimate the number of falls and thus explain the failure to establish a relationship with dual-task-related gait changes In addition, primary outcome measures varied Some studies examined the first fall following the dual-task assessment [1,6–10,13,14], whilst others examined the predictive value for recurrent falls defined as ‡2 falls during the follow-up period [6,13,14,16] Two out of four studies with equivocal or negative results used the latter outcome measure Because recurrent falls are more often related to intrinsic (i.e subject-related) risk factors for falling than isolated falls [4,5] and dual-task-related gait changes are closely associated with intrinsic risk factors for falling [6], an association between recurrent falls and dual-task-related gait changes could be postulated Intrinsic risk factors for falling are those related to various cumulated effects of chronic diseases and physiologic decline [35] These effects become even more pronounced and diverse with age, contributing to a vicious cycle of increasing frailty and increasing risk of falling The discrepancy between this hypothesis and the results could be related to an insufficient number of studies (i.e 2), which specifically explored the predictive value for recurrent falls Lastly, study samples were very heterogeneous They included frail older adults living in senior housing facilities [1,7,8,11,13] as well as healthy communitydwelling older adults [6,8,11,13–15] or inpatients Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 792 O Beauchet et al Study ID ES (95%CI) % Weight Studies with retrospective data collection of falls Shumway-Cook et al., 2000 56.00 (5.13, 611.71) 3.28 Faulkner et al., 2007* 1.34 (1.04, 1.74) 8.84 Faulkner et al., 2007† 1.42 (1.08, 1.85) 8.82 Subtotal (I-squared = 78.4%, p = 0.010) 1.62 (0.96, 2.72) 20.94 Lundin-Olsson et al., 1997 15.90 (3.02, 83.88) 4.89 Lundin-Olsson et al., 1998 10.11 (2.00, 50.98) 5.01 Lundin-Olsson et al., 2000 25.90 (7.64, 87.77) 6.19 Verghese et al., 2002* 7.03 (1.68, 29.43) 5.54 Verghese et al., 2002† 13.75 (2.26, 83.56) 4.52 Bootsma-Van Der Wiel et al., 2003 0.98 (0.65, 1.47) 8.58 Hyndman et al., 2004 2.63 (0.94, 7.38) 6.81 Andersson et al., 2006* 5.55 (1.10, 28.02) 5.01 Andersson et al., 2006† 3.89 (0.86, 17.59) 5.32 Beauchet et al., 2007 53.08 (20.65, 136.43) 7.09 Beauchet et al., 2008b 2.46 (1.28, 4.73) 7.98 Kressig et al., 2008 15.94 (3.22, 79.05) 5.06 Beauchet et al., 2008a 3.33 (1.29, 8.56) 7.08 Subtotal (I-squared = 86.9%, P = 0.000) 6.84 (3.06, 15.28) 79.06 5.30 (3.08, 9.13) 100.00 Studies with prospective data collection of falls Overall (I-squared = 87.9%, P = 0.000) NOTE: Weights are from random effects analysis *: Simple attention-demanding task †: Complex attention-demanding task 0.1 0.25 0.5 10 25 50 100 Figure Forest plot of the pooled estimated OR (ES) associated with the risk of falls according to the results from the dual-task procedure computed from the natural logarithm transformation of the OR and 95% CI I-squared (variation in OR attributable to heterogeneity) [10,12,17] No association between dual-task-related gait changes and fall incidence was found in the three studies that focused on community-dwelling older adults (i.e relatively healthy older adults) [15,16,18] In contrast, the highest predictive values for falls based on dual-task-related gait changes were found in institutionalized populations (i.e frail older adults) [1,7,8] and geriatric inpatients [12] Worsened gait performance whilst dual tasking was associated with polymedication, a well-known marker of comorbidities and frailty [36] Therefore, it might be suggested that gait changes whilst dual tasking could be a particularly significant predictor of falls amongst frail older adults The lack of standardization in dual-task paradigms certainly explains many of the discrepancies listed above A consensus needs to be reached on test conditions and data collection In contrast to a non-standardized attention-demanding task like engaging in a conversation, a well-defined and quantitative verbal fluency task, such as reciting letters of the alphabet or backward counting would improve validity, reliability, consistency and comparison of results [1,8,9,18,19] Few studies gave instructions to participants prior to dual tasking It has been shown that the dual-task interference depended on the priority given to either one of both tasks [2,3], based on the assumption that attentional resources are limited [3] Therefore, interference suggests an overload of the central resources associated with an inability to appropriately allocate attention between two simultaneously performed tasks or prioritization [2,3,37,38] Thus, gait changes whilst dual tasking, both their nature and their range, might represent the ability to develop a strategy for maintaining optimal movement in terms of attentional demand and efficiency of gait control The attentiondemanding tasks were qualitatively and quantitatively too heterogeneous, some authors using a relatively simple motor task [6–8,10] and others various cognitive tasks based on spoken verbal responses with varying degrees of difficulty [1,7–14] As a more complex cog- Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 Dual task and prediction of falls nitive dual task was related to a better fall prediction than using a simpler one [9], failure to predict falls might greatly depend on the dual task and be related to a ceiling effect of task used Walking conditions also varied in the studies As it has been well-established that a walk route including walking straight ahead, turning around and returning required more attention as opposed to walking straight alone [4,39], such conditions could also influence dualtask performance [39] The right choice of dual-task-related parameters seems to be crucial for fall prediction All, but one of the studies [11], which explored the predictive value for falling, were based on changes in gait whilst dual tasking Most studies used visual observation and recorded ambulation time and the number of steps or stops [1,6–11,13–19], although some authors suggested its poor inter-rater reliability [40] Only one study [12] used a spatio-temporal gait analysis system that allowed quantified and objective gait measurements, showing that increased stride time variability whilst counting backwards was a significant indicator of fall risk In addition, unlike most of the previous studies, one study also evaluated changes in the attentiondemanding task performance whilst counting backwards out loud from 50 [11] Subjects were then divided into two categories, according to their backward counting performance Subjects who counted more numbers whilst walking than whilst seated had a higher risk of falling than those who counted fewer numbers whilst walking The authors postulated that backward counting, being both an attention and a rhythmic task, would act as a regulator, comparable to a metronome in subjects with an irregular walking pattern and, therefore, at highest risk of falling [41] Improved counting performances in this case might be explained by a phenomenon of the two rhythms, counting and walking, being drawn toward each other and would be an indirect way to identify subjects with irregular stride Despite the use of heterogeneous dual-task conditions, the pooled OR shows a statistically significant increase in the risk of falls when subjects had changes in gait or attention-demanding task performance whilst dual tasking, this is particularly obvious in prospective studies 793 formance [11,12], give a new impulse to the understanding of dual tasking and its potential for developing new approaches in fall prevention A better analysis of changes in attention-demanding tasks, gait variability, their relationship with cognitive functions and the search for their anatomical and neurochemical correlates constitute a fascinating challenge [42] To improve the predictive value of dual task-based fall risk assessment tests, more prospective population studies are needed with larger sample sizes, better identification of confounding variables, such as health status and standardization of the methodology, mainly for the attention-demanding task Such a consensus will certainly improve fall prediction but also response to cognitive treatments such as cholinergic enhancers and other treatments that may be available in the future Acknowledgment None Author contributions Beauchet has full access to the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analyses Beauchet and Herrmann were responsible for study concept and design Dubost and Annweiler performed the acquisition of data Beauchet, Allali, Herrmann, Kressig, Bridenbaugh, Assal, Dubost and Annweiler performed the analysis and interpretation of data Beauchet, Allali, Annweiler and Dubost was responsible for drafting of the manuscript Annweiler, Herrmann, Kressig, Assal and Bridenbaugh made critical revision of the manuscript for important intellectual content Herrmann was responsible for statistical expertise Dubost and Annweiler gave administrative, technical, or material support Beauchet and Herrmann did study supervision Funding is not applicable Conflict of interest The authors have no relevant financial interest in this manuscript References Conclusions Despite conflicting early reports, changes in performance whilst dual-tasking were significantly associated with an increased risk for falling amongst older adults (pooled odds ratio = 5.3 with 95% CI = 3.1–9.1) Recent data, which focused on stride-to-stride variability and changes in attention-demanding task per- Lundin-Olsson L, Nyberg L, Gustafson Y ‘‘Stops walking when talking’’ as a predictor of falls in elderly people Lancet 1997; 349: 617 Abernethy B Dual-task methodology and motor skills reseasch: some applications and methodologies constraints J Hum Mov Stud 1988; 14: 101–132 Pashler H Dual-task interference in simple tasks: data and theory Psychol Bull 1994; 116: 220–244 Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 794 O Beauchet et al Woollacott M, Shumway-Cook A Attention and the control of posture and gait: a review of an emerging area of research Gait Posture 2002; 16: 1–14 Bloem BR, Steijns JA, Smits-Engelsman BC An update on falls Curr Opin Neurol 2003; 16: 15–26 Shumway-Cook A, Brauer S, Woollacott M Predicting the probability for falls in community-dwelling older adults using the Timed Up & Go Test Phys Ther 2000; 80: 896–903 Lundin-Olsson L, Nyberg L, Gustafson Y Attention, frailty, and falls: the effect of a manual task on basic mobility J Am Geriatr Soc 1998; 46: 758–761 Lundin-Olsson L, Nyberg L, Gustafson Y The mobility interaction fall chart Physiother Res Int 2000; 5: 190–201 Verghese J, Buschke H, Viola L, et al Validity of divided attention tasks in predicting falls in older individuals: a preliminary study J Am Geriatr Soc 2002; 50: 1572–1576 10 Andersson AG, Kamwendo K, Seiger A, Appelros P How to identify potential fallers in a stroke unit: validity indexes of test methods J Rehabil Med 2006; 38: 186– 191 11 Beauchet O, Dubost V, Allali G, Gonthier R, Herrmann FR, Kressig WR ‘‘Faster counting while walking’’ as a predictor of falls in older adults Age Ageing 2007; 36: 418–423 12 Kressig RW, Herrmann FR, Michel JP, Beauchet O Gait variability while dual-tasking: fall predictor in older inpatients? Aging Clin Exp Res 2008; 20: 123–130 13 Beauchet O, Annweiler C, Allali G, Berrut G, Herrmann FR, Dubost V Recurrent falls and dual-task related decrease in walking speed: is there a relationship? J Am Geriatr Soc 2008a; 56: 1265–1269 14 Faulkner KA, Redfern MS, Cauley JA, et al Multitasking: association between poorer performance and a history of recurrent falls J Am Geriatr Soc 2007; 55: 570– 576 15 Vaillant J, Martigne´ P, Vuillerme N, et al Prediction of falls with performance on Timed ‘‘Up-and-Go’’ and oneleg-balance tests and additional cognitive tasks Ann Readapt Med Phys 2006; 49: 1–7 16 Stalenhoef PA, Diederiks JP, Knottnerus JA, Kester AD, Crebolder HF A risk model for the prediction of recurrent falls in community-dwelling elderly: a prospective cohort study J Clin Epidemiol 2002; 55: 1088–1094 17 Hyndman D, Ashburn A Stops walking when talking as a predictor of falls in people with stroke living in the community J Neurol Neurosurg Psychiatry 2004; 75: 994–997 18 Bootsma-van der Wiel A, Gussekloo J, de Craen AJ, van Exel E, Bloem BR, Westendorp RG Walking and talking as predictors of falls in the general population: the Leiden 85-Plus Study J Am Geriatr Soc 2003; 51: 1466–1471 19 Beauchet O, Allali G, Annweiler C, et al Does change in gait while counting backward predict the occurrence of a first fall in older adults? Gerontology 2008b; 54: 217–223 20 Von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP STROBE initiative The Strengthening the Reporting of Observational Studies in Epidemiology [STROBE] statement: guidelines for reporting observational studies J Clin Epidemiol 2008; 61: 344–349 21 Shumway-Cook A, Woollacott M, Kerns KA, Baldwin M The effects of two types of cognitive tasks on postural stability in older adults with and without a history of falls J Gerontol A Biol Sci Med Sci 1997; 52: M232– M240 22 Shumway-Cook A, Woollacott M Attentional demands and postural control: the effect of sensory context J Gerontol A Biol Sci Med Sci 2000; 55: M10–M16 23 Ashburn A, Stack E, Pickering RM, Ward CD A community-dwelling sample of people with ParkinsonÕs disease: characteristics of fallers and non-fallers Age Ageing 2001; 30: 47–52 24 Lajoie Y, Gallagher SP Predicting falls within the elderly community: comparison of postural sway, reaction time, the Berg balance scale and the Activities-specific Balance Confidence (ABC) scale for comparing fallers and nonfallers Arch Gerontol Geriatr 2004; 38: 11–26 25 Ashburn A, Stack E, Pickering RM, Ward CD Predicting fallers in a community-based sample of people with ParkinsonÕs disease Gerontology 2001; 47: 277–281 26 Bergland A, Wyller TB Risk factors for serious fall related injury in elderly women living at home Inj Prev 2004; 10: 308–313 27 Bloem BR, Grimbergen YA, Cramer M, Valkenburg VV ‘‘Stops walking when talking’’ does not predict falls in ParkinsonÕs disease Ann Neurol 2000; 48: 268 28 Bloem BR, Grimbergen YA, Cramer M, Willemsen M, Zwinderman AH Prospective assessment of falls in ParkinsonÕs disease J Neurol 2001; 248: 950–958 29 Dibble LE, Lange M Predicting falls in individuals with Parkinson disease: a reconsideration of clinical balance measures J Neurol Phys Ther 2006; 30: 60–67 30 Camicioli R, Licis L Motor impairment predicts falls in specialized Alzheimer care units Alzheimer Dis Assoc Disord 2004; 18: 214–218 31 Hyndman D, Ashburn A, Yardley L, Stack E Interference between balance, gait and cognitive task performance among people with stroke living in the community Disabil Rehabil 2006; 28: 849–856 32 Springer S, Giladi N, Peretz C, Yogev G, Simon ES, Hausdorff JM Dual-tasking effects on gait variability: the role of aging, falls, and executive function Mov Disord 2006; 21: 950–957 33 Toulotte C, Thevenon A, Watelain E, Fabre C Identification of healthy elderly fallers and non-fallers by gait analysis under dual-task conditions Clin Rehabil 2006; 20: 269–276 34 Mackinnon A A spreadsheet for the calculation of comprehensive statistics for the assessment of diagnostic tests and inter-rater agreement Comput Biol Med 2000; 30: 127–134 http://www.mhri.edu.au/biostats/DAG_Stat/ updated May 9, 2000 (accessed 25/03/2009) 35 Fried LP, Bandeen-Roche K, Kasper JD, Guralnik JM Association of comorbidity with disability in older women: the WomenÕs Health and Aging Study J Clin Epidemiol 1999; 52: 27–37 36 Beauchet O, Dubost V, Herrmann F, Rabilloud M, Gonthier R, Kressig RW Relationship between dual-task related gait changes and intrinsic risk factors for falls among transitional frail older adults Aging Clin Exp Res 2005; 17: 270–275 37 Yogev-Seligmann G, Hausdorff JM, Giladi N The role of executive function and attention in gait Mov Disord 2008; 23: 329–342 Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795 Dual task and prediction of falls 38 Verghese J, Kuslansky G, Holtzer R, et al Walking while talking: effect of task prioritization in the elderly Arch Phys Med Rehabil 2007; 88: 50–53 39 Kressig RW, Beauchet O, European GAITRite Network Group Guidelines for clinical applications of spatiotemporal gait analysis in older adults Aging Clin Exp Res 2006; 18: 174–176 40 Eastlack ME, Arvidson J, Snyder-Mackler L, Danoff JV, McGarvey CL Interrater reliability of videotaped obser- 795 vational gait-analysis assessments Phys Ther 1991; 71: 465–472 41 Ebersbach G, Dimitrijevic MR, Poewe W Influence of concurrent tasks on gait: a dual-task approach Percept Mot Skills 1995; 81: 107–113 42 Rosano C, Brach J, Studenski S, Longstreth WT Jr, Newman AB Gait variability is associated with subclinical brain vascular abnormalities in high-functioning older adults Neuroepidemiology 2007; 29: 193–200 Ó 2009 The Author(s) Journal compilation Ó 2009 EFNS European Journal of Neurology 16, 786–795