Inaccurate judgement of reach is associated with slow reaction time, poor balance, impaired executive function and predicts prospective falls in older people with cognitive impairment.

BACKGROUND: Awareness of physical ability may impact fall risk during everyday tasks. Therefore, we investigated perceived reach (PR; estimation of furthest reach distance), maximal reach (MR) and reach judgement error (RJE), and their relationships with neuropsychological and physical performance, and falls in older people with cognitive impairment (CI).

METHODS: Prospective cohort study of 110 (mean age = 82 ± 7 years; female = 52%) older people with mild-moderate CI (MMSE 11-23; Addenbrooke's Cognitive Examination-Revised (ACE-R) < 83). PR, MR and detailed neuropsychological and physical assessments were assessed at baseline. Participants were divided into tertiles based on their absolute RJE. Falls were recorded prospectively over 12 months with the assistance of carers.

RESULTS: The populations mean MR was 79 ± 10 cm and PR was 75 ± 13 cm, indicating participants tended to underestimate their reach ability. The large RJE tertile performed significantly poorer in measures of global cognition (ACE-R; OR 0.54 95%CI 0.31-0.95) and executive function (Trail Making Test B; OR 1.84 95%CI 1.00-3.36) and had increased concern about falling (Falls Efficacy Scale-International; OR 2.01 95% CI 1.06-3.79) compared to the minimal RJE tertile. The moderate and large RJE tertile groups had significantly slower hand reaction time and larger postural sway on foam compared to the minimal RJE tertile. Each 1% increase in RJE increased the risk of falls by 2% (RR 1.02 95%CI 1.01-1.03). This relationship withstood adjustment for other fall risk factors (sway on foam, Trail Making Test B and ACE-R).

CONCLUSIONS: Inaccurate reach judgement predicts future falls and is associated with poorer global cognitive performance and executive function, increased concern about falling, slower reaction time and poorer balance. Our results offer insight into the disparity between actual and perceived physical capabilities in people with CI, and how this impacts their risk of falling.