Association between functional performance and executive cognitive functions in an elderly population including patients with low ankle-brachial index

Abstract

Introduction: Peripheral arterial disease, as measured by the ankle-brachial index (ABI), is prevalent among the elderly, and is associated with functional performance, assessed by the 6-minute walk test (6MWT). Executive cognitive function (ECF) impairments are also prevalent in this population, but no existing study has investigated the association between ECF and functional performance in an elderly population including individuals with low ABI.

Aim: To investigate the association between functional performance, as measured by the 6MWT, and loss in ECF, in an elderly sample including individuals with low ABI.

Method: The ABI group was formed by 26 elderly individuals with low ABI (mean ABI: 0.63±0.19), and the control group was formed by 40 elderly individuals with normal ABI (mean ABI: 1.08±0.07). We analyzed functional performance using the 6MWT, global cognition using the Mini-Mental State Examination (MMSE), and ECF using the Digit Span for assessing attention span and working memory, the Stroop Color Word Test (SCWT) for assessing information processing speed and inhibitory control/impulsivity, and the Controlled Oral Word Association Test (COWAT) for assessing semantic verbal fluency and phonemic verbal fluency. We also used a factor analysis on all of the ECF tests (global ECF).

Results: Before adjustment, the ABI group performed worse on global cognition, attention span, working memory, inhibitory control/impulsivity, semantic verbal fluency, and phonemic verbal fluency. After adjustment, the ABI group performance remained worse for working memory and semantic verbal fluency. In a simple correlation analysis including all of the subjects, the 6MWT was associated with global cognition, attention span, working memory, information processing speed, inhibitory control/impulsivity, semantic verbal fluency, and global ECF. After adjustment, all the associations remained statistically significant.

Conclusion: This study found an independent association between functional performance and ECF in an elderly population including low ABI individuals, showing that, in elderly populations with functional impairment, ECF may also be impaired.

Keywords: 6-minute walk test; cognition; vascular disease.

Figure 1

Associations between functional performance and ECF. Notes: (A) 6MWT vs MMSE; (B) 6MWT vs Digit Forward; (C) 6MWT vs Digit Backward; (D) 6MWT vs SCWT I; (E) 6MWT vs SCWT II; (F) 6MWT vs SCWT III; (G) 6MWT vs COWAT – letters FAS; (H) 6MWT vs COWAT – Animals; (I) 6MWT vs ECF factor. Abbreviations: 6MWT, 6-minute walk test; MMSE, Mini-Mental State Examination; SCWT, Stroop Color Word Test; COWAT, Controlled Oral Word Association Test; ECF, executive cognitive functions.