Reaction Time and Postural Sway Modify the Effect of Executive Function on Risk of Falls in Older People with Mild to Moderate Cognitive Impairment

Morag E Taylor; Stephen R Lord; Kim Delbaere; Susan E Kurrle; A Stefanie Mikolaizak; Jacqueline C T Close

doi:10.1016/j.jagp.2016.10.010

Reaction Time and Postural Sway Modify the Effect of Executive Function on Risk of Falls in Older People with Mild to Moderate Cognitive Impairment

Am J Geriatr Psychiatry. 2017 Apr;25(4):397-406. doi: 10.1016/j.jagp.2016.10.010. Epub 2016 Oct 25.

Authors

Morag E Taylor¹, Stephen R Lord², Kim Delbaere², Susan E Kurrle³, A Stefanie Mikolaizak⁴, Jacqueline C T Close⁵

Affiliations

¹ Falls, Balance and Injury Research Center, Neuroscience Research Australia, Australia; Cognitive Decline Partnership Centre, Sydney Medical School, University of Sydney, Australia; Department of Medicine, Prince of Wales Clinical School, University of New South Wales, Sydney, Australia. Electronic address: m.taylor@neura.edu.au.
² Falls, Balance and Injury Research Center, Neuroscience Research Australia, Australia; School of Public Health and Community Medicine, Prince of Wales Clinical School, University of New South Wales, Sydney, Australia.
³ Cognitive Decline Partnership Centre, Sydney Medical School, University of Sydney, Australia.
⁴ Falls, Balance and Injury Research Center, Neuroscience Research Australia, Australia.
⁵ Falls, Balance and Injury Research Center, Neuroscience Research Australia, Australia; Department of Medicine, Prince of Wales Clinical School, University of New South Wales, Sydney, Australia.

PMID: 28063853
DOI: 10.1016/j.jagp.2016.10.010

Abstract

Objectives: To explore the relationship between cognitive performance and falls in older people with mild to moderate cognitive impairment (CI) by investigating the mediational effects of medical, medication, neuropsychological, and physiological factors.

Design: Secondary analysis, prospective cohort study.

Setting: Community and low-level care.

Participants: 177 older people (aged 82 ± 7 years) with mild to moderate CI (MMSE 11-23; ACE-R < 83).

Measurements: Global cognition and six neuropsychological domains (memory, language, visuospatial, processing speed, executive function [EF], and affect) were assessed. Participants also underwent sensorimotor and balance assessments. Falls were recorded prospectively for 12 months.

Results: The EF domain was most strongly associated with multiple falls (relative risk [RR]: 1.50, 95% CI: 1.18-1.91). Global cognition was not associated with falls (RR: 1.09, 95% CI: 0.92-1.30). Additional analyses showed that participants with poorer EF (median cutpoint) were more likely to be taking centrally acting medications and were less physically active. They also had significantly worse vision, reaction time, knee extension strength, balance (postural sway, controlled leaning balance), and higher physiological fall risk scores. Participants with poorer EF were 1.5 times (RR: 1.50, 95% CI: 1.03-2.18) more likely to have multiple falls. Mediational analyses demonstrated that reaction time and postural sway reduced the relative risk of EF on multiple falls by 31% (RR: 1.19, 95% CI: 0.81-1.74).

Conclusions: Within this sample of older people with mild to moderate CI, poorer EF increased the risk of multiple falls. This relationship was mediated by reaction time and postural sway,suggesting cognitively impaired older people with poorer EF may benefit from fall prevention programs targeting these mediating factors.

Keywords: Dementia; accidental falls; cognitive impairment; executive function; risk factors.

MeSH terms

Accidental Falls*
Aged
Aged, 80 and over
Cognitive Dysfunction / physiopathology*
Executive Function / physiology*
Female
Humans
Male
Postural Balance / physiology*
Prospective Studies
Reaction Time / physiology*
Risk Factors