Reduce falls by improving cognitive function

Dr. Teresa Liu-Ambrose (biography and disclosures)

What I did before

Falls are a common geriatric syndrome and are the third leading cause of chronic disability worldwide. Falls are not random events and occur, at least in part, due to impaired physiological function, such as impaired balance, and cognitive impairment. Primary care physicians can use the Physiological Profile Assessment screening tool – it has normative data (65 and up) and provides information for patients as well.¹

Results from both systematic reviews and meta-analyses highlight that exercise can play an important role in falls prevention.² The Otago Exercise Program (OEP) – a physical therapist-delivered, or nurse-delivered, progressive home-based strength and balance training program tailored for older adults – is the exercise training program with the strongest evidence for falls prevention in older adults. ² The instruction guide, that describes the program exercises, is available to health professionals at www.acc.co.nz.

The widely accepted dogma is that improved physical function, balance and muscle strength, underlies the effectiveness of the exercise in reducing falls. We recently challenged this current paradigm by proposing the “central benefit model” of exercise in falls prevention.³ This framework highlights that improved cognitive function, in particular executive functions, may be a very important mechanism by which the exercise reduces falls and improves overall mobility in older adults.

What changed my practice

Findings from recent randomized controlled trials suggest that exercise reduce falls via mechanisms other than improved physiological function. Specifically, the evidence supports the hypothesis that exercise may reduce falls by improving cognitive function. Physical activity maintains and enhances cognitive function across the lifespan. Aerobic training had robust but selective benefits for cognitive function; the largest benefits occurred for executive functions. Resistance training also benefited executive functions and its associated functional plasticity.

Our randomized controlled trial published in 2008 found that the OEP reduced falls by 47% among older adults with a significant history of falls — in the absence of improvement in physical function (i.e., minimal change in balance and muscle strength).⁴ Notably, cognitive performance of selective attention and conflict resolution significantly improved in the OEP group as compared with the usual care (i.e., control) group. Another randomized controlled trial we published in 2010 demonstrated that improved selective attention and conflict resolution secondary to 12 months of progressive resistance training was associated with improved usual gait speed.⁵ Gait speed is a significant and independent predictor of falls and fracture risk in older women.⁶ Moreover, improved gait speed is a predictor of substantial reduction in mortality.⁷

What I do now

Given the strong association between executive functions and falls, we recommend that falls risk screening include far greater attention to assessment of cognitive processes – in particular executive processes of selective attention and conflict resolution and dual-tasking. If testing, the Montreal Cognitive Assessment (MoCA) is much more sensitive to changes in executive functions than Mini-Mental State Examination (MMSE). ⁸ We use the Stroop or Flanker task to specifically tap into selective attention and conflict resolution; we use a computer paradigm for dual tasking. But for a clinical setting, the Montreal Cognitive Assessment (MoCA) would be a nice screen for both MCI and executive deficits. Recent trials (2010 and onwards) suggest that exercise is beneficial for those with mild cognitive impairment (MCI).⁹ Both resistance training and aerobic training – thus far have good evidence for promoting executive functions. However, general environment enrichment (i.e., volunteer, socialization) also have evidence for promoting executive functions. Thus, the general recommendation to have older adults to continually to be engaged physically and mentally is warranted. In addition, future falls prevention strategies should consider intervention components that promote executive functions.

References

1. Lord SR, Menz HB, Tiedemann A. A physiological profile approach to falls risk assessment and prevention. Phys Ther. 2003;83: 237-252. (View with CPSBC or UBC)
2. Gillespie LD, Robertson MC, Gillespie WJ, et al. Interventions for preventing falls in older people living in the community. Cochrane Database Syst Rev. 2009:CD007146. (View with CPSBC or UBC)
3. Liu-Ambrose T, Nagamatsu LS, Hsu CL, Bolandzadeh N. Emerging concept: ‘central benefit model’ of exercise in falls prevention. Br J Sports Med. (View with CPSBC)
4. Liu-Ambrose T, Donaldson MG, Ahamed Y, et al. Otago home-based strength and balance retraining improves executive functioning in older fallers: a randomized controlled trial. J Am Geriatr Soc. 2008: 56:1821-1830. (View with CPSBC)
5. Liu-Ambrose T, Nagamatsu LS, Graf P, Beattie BL, Ashe MC, Handy TC. Resistance training and executive functions: a 12-month randomized controlled trial. Arch Intern Med. 2010: 170:170-178. (View)
6. Dargent-Molina P, Favier F, Grandjean H, et al. Fall-related factors and risk of hip fracture:  The EPIDOS prospective study. Lancet. 1996: 348:145-149. (View with CPSBC)
7. Hardy SE, Perera S, Roumani YF, Chandler JM, Studenski SA. Improvement in usual gait speed predicts better survival in older adults. J Am Geriatr Soc. 2007: 55:1727-1734. (View with CPSBC)
8. Nasreddine ZS, Phillips NA, Bédirian V , et al. The Montreal Cognitive Assessment, MoCA: a brief screening tool for mild cognitive impairment. J Am Geriatr Soc. 2005 Apr;53(4):695-9. (View with CPSBC)
9. Examples: JAMA 2010, Archives of Neurology 2010, Archives of Internal Medicine, 2012

Resource

http://www.acc.co.nz/PRD_EXT_CSMP/groups/external_providers/documents/publications_promotion/prd_ctrb118334.pdf

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Reduce falls by improving cognitive function

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