The Role of Physical Fitness in the Neurocognitive Performance of Task Switching in Older Persons with Mild Cognitive Impairment

Abstract

Abstract. Although elderly people with amnestic mild cognitive impairment (aMCI) have been found to show impaired behavioral performance in task switching, no research has yet explored the electrophysiological mechanisms and the potential correlation between physical fitness and neurocognitive (i.e., behavioral and electrophysiological) performance in aMCI. The present study was thus aimed to examine whether there are differences in electrophysiological (i.e., event-related potential) performance between aMCI participants and controls when performing a task-switching paradigm, and to investigate the role of physical fitness in the relationship between neurocognitive performance and aMCI. Sixty participants were classified into aMCI (n = 30) and control (n = 30) groups, and performed a task-switching paradigm with concomitant electrophysiological recording, as well as underwent senior functional physical fitness tests. The aMCI group showed comparable scores on most parts of the physical fitness tests, but reduced lower body flexibility and VO 2max as compared to the control group. When performing the task-switching paradigm, the aMCI group showed slower reaction times in the heterogeneous condition and larger global switching costs, although no significant difference was observed in accuracy rates between the two groups. In addition, the aMCI group showed significantly prolonged P3 latencies in the homogeneous and heterogeneous conditions, and a smaller P3 amplitude only in the heterogeneous condition. The level of cardiorespiratory fitness was significantly correlated with P3 amplitude in the aMCI group, particularly in the heterogeneous condition of the task-switching paradigm. These results show that the aMCI group exhibited abnormalities in their neurocognitive performance when performing the task-switching paradigm and such a deficit was likely associated with reduced cardiorespiratory fitness, which was shown to be the important predictor of neurocognitive performance.

An acute bout of aerobic or strength exercise specifically modifies circulating exerkine levels and neurocognitive functions in elderly individuals with mild cognitive impairment

“…Previous studies have proposed that the ERP P3 component is sensitive enough to identify an early stage of cognitive impairment in the elderly with MCI ( Bennys et al, 2007 , Jiang et al, 2015 , Tsai et al, 2016a ). Even though Wang et al, 2013 found that older adults with MCI showed longer P3 latencies than healthy controls when performing the Flanker task, and Kamijo et al, 2009 found that the P3 latency following a bout of light or moderate aerobic exercise was shorter than during the baseline session in older adults when performing the Flanker task, acute bouts of exercise, regardless of aerobic or resistance mode, failed to modulate the P3 latency in the present study.…”

“…After baseline measurements as mentioned below, they were randomly assigned to either an aerobic exercise (AE, n = 25), a resistance exercise (RE, n = 21) or a control group (n = 20). The clinical inclusion criteria for the participants with aMCI were as follows while stratifying for age and gender ( Petersen, 2004 , Petersen et al, 1999 , Suk et al, 2014 , Tsai et al, 2016a ): (1) subjective memory complaints confirmed by family members; (2) objective memory impairment for age; (3) a Clinical Dementia Rating (CDR) of 0.5; (4) Mini-Mental State Examination (MMSE) score > 24 ( Folstein et al, 1975 ); (5) absence of significant levels of impairment in other cognitive domains (e.g., attention, language, orientation, and abstraction), as assessed by the Cognitive Abilities Screening Instrument (CASI) ( Teng et al, 1994 ); (6) largely intact functional activities of daily living; (7) no brain abnormalities (e.g., stroke and malignant brain tumors) seen via structural MRI scans; (8) an absence of dementia; and (9) non-depressed, with a score of < 13 on the Beck Depression Inventory, 2nd edition (BDI-II) ( Beck et al, 1996 ). Single photon emission computed tomography (SPECT) for functional examinations and computed tomography (CT) for structural brain examinations were performed when more information was needed to confirm the diagnosis.…”

“…However, consensus has not yet been reached concerning the effects of acute exercise on circulating levels of these exerkines in the elderly with pathology. Older individuals with MCI have lower physical fitness ( Tsai et al, 2016a ), and physical activity is strongly associated with exercise-induced systemic release of these exerkines ( Wolf et al, 2006 ). Accordingly, more work is needed to explore the hypothesis that the amount of exerkines could be effectively increased via physical exercise in MCI individuals who could have deficiencies in their secretion.…”

“…The first purpose of this work was thus to examine the effects of acute aerobic or resistance exercise on the neurocognitive performance and molecular changes in older persons with aMCI. In addition, several reports over the past decade demonstrated electrophysiological impairments in aMCI patients ( Bennys et al, 2007 , Cid-Fernández et al, 2014 , Tsai et al, 2016a ), and exercise-induced peripheral growth factors are strongly associated with cognition/clearance of brain Aβ and, importantly, can be up-regulated by physical exercise ( Carro et al, 2002 , Fabel et al, 2003 , Gomez-Pinilla et al, 1997 ). However, their role in acute-exercise-induced changes in neurocognitive performance in aMCI is still not clear.…”

A systematic review of cognitive event-related potentials in mild cognitive impairment and Alzheimer’s disease

“…Sixteen of the 29 total studies assessing P300 amplitude in MCI reported no significant difference between groups [i.e., 55%;11,22,28-30,46,51,78,94,105- 107,114,133,139,142]. Of the remaining 13 studies that reported group differences (i.e., 45%), 11 reported smaller P300 amplitudes in MCI compared to HC groups [i.e., 85% of significant studies; 38% of total studies;12,23,53,57,59,81,83,86,138,145,148], including one that specified smaller amplitudes in progressive MCI compared to both non-progressive MCI and healthy controls[12]. Of the studies that detected group differences, 73% used more complexRunning head: SYSTEMATIC REVIEW OF COGNITIVE ERPS IN MCI AND AD 20…”