A Simple Sensitive Method for Measuring Borderline Mental Fatigue

_____________________________________________________________________________________________________ *Corresponding author: E-mail: [email protected];

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A Simple Sensitive Method for Measuring Borderline

Mental Fatigue

Leyla Aydin

, Nimet Unay Gundogan

, Erhan Kiziltan

, Canan Yazici

,

Beste Ozturk

, Burçak Kara

, Yağiz Yeşilova

, Irmak Erdemir

, Cem Bulbul

and Esra Oner

1

Department of Physiology, Faculty of Medicine, Baskent University, Ankara, Turkey. 2_{Department of Biostatistics, Faculty of Medicine, Baskent University, Ankara, Turkey.}

3_{Faculty of Medicine, Baskent University, Ankara, Turkey.}

Authors’ contributions

This work was carried out in collaboration between all authors. Authors LA, NUG and EK managed the literature searches, designed the study, wrote the protocol and wrote the first draft of the manuscript. Author CY performed statistical analysis. Authors BO, BK, YY, IE, CB and EO performed tests and questionnaires. All authors read and approved the final manuscript.

Article Information

DOI: 10.9734/BJMMR/2016/25893 Editor(s): (1) Jingli Xu, College of Pharmacy, University of New Mexico, USA. Reviewers: (1) Jera Kruja, University of Medicine, Albania. (2)David Castro Costa, Centro Hospitalar de Sao Joao, Portugal. Complete Peer review History:http://sciencedomain.org/review-history/14467

Received 25th March 2016 Accepted 23rd April 2016 Published 5th May 2016

ABSTRACT

Mental fatigue [MF] is a critical condition that can accompany cognitive dysfunction. Various surveys have been used to determine the MF state. However, differences in participants' perception levels' can decrease' survey specificity, which therefore should be supported using objective methods. This study describes a new and simple MF scale based on evaluating results from the Piper Fatigue Scale [PFS], together with the results for reaction times. In the study, 29 healthy, right-handed, male, medical student volunteers were included. Attending a theoretical class for 4 hours was used as the MF model. PFS was applied before and after the MF model to determine their levels of vulnerability to fatigue and perception of fatigue qualitatively. The finger tapping test [FTT] and simple and complex visual reaction time [VRT] tests were used to determine physical fatigue and MF quantitatively. There were no significant differences between pre- and post-fatigue PFS scores or FTT and simple VRT results [p=0.531, p=0.160, p=0.065, respectively]. However, the complex

Aydin et al.; BJMMR, 15(7): 1-8, 2016; Article no.BJMMR.25893

VRT was significantly longer after the MF model [p<0.05]. This study showed that borderline MF, which cannot be determined by the PFS alone, might be accomplished when tested with the complex VRT test that keeps participants in a vigilant state.

Keywords: Mental fatigue; qualitative evaluation; piper fatigue Scale; quantitative evaluation; complex visual reaction time.

1. INTRODUCTION

Mental fatigue [MF] is a temporary symptom expressed by abstract concepts, such as exhaustion, fatigue, drowsiness, a worn out feeling and strain [1]. It is a mental condition with

critical, concrete results such as decreased work productivity, cognitive dysfunction and

concentration impairment, and it increases the risks of making mistakes in daily life and causing accidents in occupational life [2]. MF may appear in daily mental activities of healthy individuals and may be seen as a nonspecific symptom in various disorders such as Parkinson’s disease [3], multiple sclerosis [4], primary biliary cirrhosis [5] autonomic dysfunction [6] and traumatic brain injury [7]. Apart from being a medical problem, determining the presence and level of MF correctly is important, since it impacts many aspects of life including occupational life.

Currently, several scales and surveys are used to evaluate MF including the Fatigue Impact Scale [8], Mental Fatigue Scale [7], Multidimensional Fatigue Symptom Inventory-20 [9], Multidimensional Fatigue Symptom Inventory-Short Form [10], Piper Fatigue Scale [PFS] [11], visual analog scale [12] and Tower of London test [1]. Among these abstract scales, the PFS is the most frequently used and measures the abstract perceptions of the participant, which are divided into four subdimensions: behavioral/severity, affective meaning, sensory and cognitive/mood subscales [11,13].

Evaluation of abstract and nonspecific MF symptoms using abstract surveys and scales based on perceptions hinders achieving reliable results [14,15]. Therefore, associating or supporting abstract evaluations such as PFS using concrete methods is important to reach more accurate results concerning the presence and level of MF. Subsequently, various groups have attempted to develop reliable scales for MF using concrete methods to define and analyze the association of MF level with motor and cognitive performance. In one study, MF was achieved using a 2-hour cognitive task, and the relationship between regulation skills in motor

and perceptual processes and the target-driven behaviors was investigated. The participants with MF had a worse performance in the Tower of London test, which is a mental planning scale [1]. In another study, the participants underwent a continuous performance test [CPD] for 90 min. A CPD measures the ability to maintain attention and to track the changes resulting from stimuli flowing on the computer screen, which when performed for a long time, causes MF. The MF achieved in this manner was shown to affect intermittent running performance unfavorably in team sport players [16]. Xia et al. [17] used a reaction time task to achieve MF and investigated the relationship between MF and non-invasive physiological parameters and advocated that monitoring electrodermal activity, heart rate and heart rate variability could be a practical approach for evaluating MF.

The evaluation of MF using concrete tests based on motor and cognitive performance will contribute to establishing directive scales, such as creating an action plan in occupational life, preparing a curriculum in education and evaluation of the related disorders. In this study, we evaluated the results of the PFS, a subjective evaluation of MF level, together with the results of an objective method, namely reaction time, and defined a simple, user-friendly test system for measuring MF.

2. MATERIALS AND METHODS

This study was approved by the Baskent University Institutional Review Board and Ethics Committee [Project no. KA14/60] and supported by the Baskent University Research Fund.

2.1 Participants

previous 30 min and presence of color blindness were evaluated before the test. The exclusion criteria included smoking/ alcohol consumption [18,19], sleeping less than 5 hours the night before the test [20], consumption of more than 1 cup of coffee or more than 2 cups of tea [21], color blindness and exercising or strenuous activity before the test [22].

2.2 Determining Hand Preference

The Turkish version of “Oldfield Inventory” was used to determine the dominant hand [23]. The inventory included questions regarding writing, drawing, throwing a stone or ball, using scissors, using a toothbrush, using a knife without a fork, using a fork, using a broom, striking a match and opening the lid of a bottle. The results were analyzed according to the Geschwind score [24,25].

2.3 Determining Color Blindness

The Color Blindness Mass Screening Test described by Gündoğan et al. [25] was used to determine color blindness. The test consisted of 24 plates, which the participants were asked to read and then close their eyes for 4 seconds to relax them between plate readings. The subjects who read all plates correctly were considered normal and those who had four or more mistakes as color blind.

2.4 MF Model

Daily educational activities can cause MF in students [26]. Washer et al. [27] showed that attending a theoretical class for 4 hours caused MF. Therefore, in our study, attending a theoretical class for 4 hours between 9:00 am and 1:00 pm was used as the MF model.

2.5 PFS

The fatigue level of the participants was measured using PFS, an abstract, paper-and-pencil test validated in Turkish [11]. Items 2-7 of the PFS comprise the behavioral/severity subscale to evaluate the effect and severity of fatigue on life perceptions. Items 8-12 are the affective meaning subscale and encompass the emotional meaning attributed to fatigue. Items 13-17 reflect mental, physical and emotional symptoms of fatigue and constitute the sensory subscale. The cognitive/mood subscale consists of items 18-23 and examines the effects of

fatigue on cognitive functions and mood. Each item is answered on a point scale: 0 indicating the best and 10 the worst. The scale also contains five items [items 1 and 24-27] that are not used to determine the fatigue score but are important for evaluation of fatigue-related aspects. Item 1 evaluates the duration of fatigue, and items 24-27 include open-ended questions via which the participant may express his/her opinions on fatigue. The subscale scores are calculated by summing up the scores of all items and dividing by the number of items [11,13].

2.6 Application of PFS

The participants completed PFS twice, before and after the fatigue model. The scale was completed in a quiet room, free of external stimuli.

2.7 Finger Tapping Test [FTT] and Visual Reaction Time [VRT]

A computer-based FTT was used for quantitative evaluation of motor and mental fatigue [28]. Motor fatigue was analyzed using the FTT module of the test system [29]. The simple and complex VRT test modules of the system were used to determine MF. The system software automatically measures the intertap interval [ITI] in the FTT and time of response to the stimulus in the VRT with a high time resolution. The data are saved to the computer’s hard drive for further analysis. Special care was taken to ensure the comfort of the participants during the test; they were seated comfortably in an armchair 50 cm away from the computer screen with a support for their wrists [30]. The pre-fatigue measurements were taken between 8:00 am and 9:00 am and the measurements performed after a 4-hour theoretical lecture given between 1:00 pm and 2:00 pm. The post-fatigue tests were performed 1 month later to exclude the learning factor effect.

2.8 Application of FTT

After given brief instructions, the participants were asked to press a predetermined keyboard key successively with their right index finger for 20 s as fast as possible.

2.9 Application of the Simple VRT Test

Aydin et al.; BJMMR, 15(7): 1-8, 2016; Article no.BJMMR.25893

yellow-colored circular object 5 cm in diameter on a black screen was used as the visual stimulus. The stimuli were displayed on the computer screen with constant delays, and the participants were asked to press the predetermined keyboard key as soon as they saw the stimulus on the screen.

2.10 Application of Complex VRT Test

In the complex VRT test, the stimuli used in the simple VRT test were displayed on the computer screen at random delays to give an additional task to the participants and keep them vigilant. Duration of the delay was determined by the system and was 4 s at maximum. The participants were asked to press the predetermined keyboard key as soon as they saw the stimulus on the screen.

2.11 Statistical Analysis

Normality of distribution was determined using the Shapiro-Wilk test. The homogeneity of the group variances was analyzed using the Levene test. The means that fulfilled the prerequisites for the parametric tests were compared between two dependent groups using the paired t-test and among more than two dependent groups using repeated measures analysis of variance and the Bonferroni test for multiple comparisons. The medians that did not fulfill the prerequisites for the parametric tests were compared between two dependent groups using the Wilcoxon test and among more than two dependent groups using the Friedman test and the Bonferroni-Dunn test for multiple comparisons. A p-value < 0.05 was considered to indicate statistical significance. Data analysis was performed using the SPSS 17.0 statistical package program [SPSS Ver. 17.0, Chicago IL, USA].

3. RESULTS

A total of 29 male university students with a mean age of 19.8±0.3 years, a mean height of 178.5±6.4 cm and a mean BMI of 23.8±2.8 kg/m2

were included in this study. The demographic characteristics of the participants showed a homogenous distribution and are presented in Table 1. The results of the Oldfield Inventory analyzed according to the Geschwind score showed that 48.2% of the participants were strongly right-handed and 51.8% were weakly right-handed.

Table 2 shows the duration of fatigue, the total fatigue score and the scores of fatigue subscales determined using the PFS before and after performing the fatigue model, as well as the mean percent [%] change and levels of statistical significance. All parameters analyzed using the PFS showed a 7.1 - 98.9% proportional increase after versus before performing the fatigue model. However, none of the proportional changes were statistically significant [p = 0.065 for duration of fatigue, p = 0.157 for behavioral/severity subscale, p = 0.382 for affective meaning subscale, p = 0.410 for sensory subscale, p = 0.066 for cognitive/mood subscale and p = 0.531 for total fatigue score].

The results of the FTT pertaining to motor fatigue are presented in Table 3. Pre-fatigue and post-fatigue mean ITI values were used as a post-fatigue scale [31] and did not show statistically significant differences [p = 0.16].

The quantitative results of the simple and complex VRT tests performed before and after MF are presented in Table 4. In the simple VRT test, pre- and post-fatigue mean response times did not show any significant differences [215.14±33.20 ms, 230.10±27.46 ms, respectively; p = 0.07]. The pre- and post-fatigue response times were 308.41±40.26 ms and 324.59±39.28 ms, respectively, in the complex VRT test, showing a significant difference [p<0.05].

Motor function tests, VRT tests and PFS scores performed before and after the defined fatigue model are shown graphically in Fig. 1. Among those, only the change in the complex VRT test was significant [p<0.05].

Table 1. The demographic characteristics of the participants [n=29]

Characteristic Mean Standard

deviation

Minimum Maximum

Age [years] 19.8 0.3 18 23

Height [cm] 178.5 6.4 167 188

Table 2. Piper fatigue scores, proportional changes and significance levels of the participants [n=29, scoring: 0 best, 10 worst

PFS subscales Before fatigue

Duration of fatigue [hours] 43.7±13.6 Behavioral/ severity subscale 2.19±1.72 Affective meaning subscale 3.27±1.76 Sensory subscale 3.99±2.16 Cognitive/ mood subscale 3.45±2.84 Total fatigue score 3.22±1.68

Table 3. Mean ± standard deviation, median, minimum, maximum values of ITI values of pre and post- fatigue FTT measurements, and their levels of significance

Mean ± Standard deviation [ms] Median [Min - Max]

Table 4. Mean ± standard deviation

fatigue simple and complex VRT measurements, and their levels of significance

Before fatigue Mean ± SD [ms Median [Min

Simple VRT 215.14±33.20 212 [160 -283

Complex VRT 308.41±40.26 307 [236-409]

Fig. 1. Finger tapping test [FTT], simple visual reaction time time [CVRT] tests, total fatigue score

The first vertical [left] axis is defined for FTT, SVRT and CVRT, and the second vertical [right] axis is defined for TFS. The data are given as means±

4. DISCUSSION

MF is a critical mental state that may be experienced during, and causes limitations in, a number of daily activities including education, sports and occupational life. Evaluation of MF is important to increase performance, productivity

Piper fatigue scores, proportional changes and significance levels of the participants n=29, scoring: 0 best, 10 worst].The data are presented as “Mean ± Standard deviation”

Before fatigue After fatigue Proportional change [%]

43.7±13.6 86.9±26.9 98.9 2.19±1.72 2.66±1.60 21.4 3.27±1.76 3.66±2.02 11.9 3.99±2.16 4.38±1.93 9.7 3.45±2.84 3.92±1.17 13.6 3.22±1.68 3.45±1.44 7.1

Table 3. Mean ± standard deviation, median, minimum, maximum values of ITI values of pre fatigue FTT measurements, and their levels of significance [n=29

Before fatigue After fatigue

138.48±17.14 136.83±18.79 136 [106-181] 134 [112-195]

Table 4. Mean ± standard deviation [SD], median, minimum, maximum values of pre fatigue simple and complex VRT measurements, and their levels of significance

Before fatigue After fatigue

ms] Min - Max]

Mean ± SD [ms] Median [Min - Max]

215.14±33.20 230.10±27.46 283] 231 [172-287]

308.41±40.26 324.59±39.28 ] 320 [251-398]

, simple visual reaction time [SVRT], complex visual reaction tests, total fatigue score [TFS] and their levels of significance [

axis is defined for FTT, SVRT and CVRT, and the second vertical FS. The data are given as means±standard deviation [*: p<0.05, n = 29

MF is a critical mental state that may be experienced during, and causes limitations in, a number of daily activities including education, sports and occupational life. Evaluation of MF is important to increase performance, productivity

and success during those activities as well as to minimize work accidents.

Numerous easy-to-use fatigue scales/surveys were developed for this purpose. Howev

been suggested that different perception levels of the individuals decreased specificity of the

Piper fatigue scores, proportional changes and significance levels of the participants The data are presented as “Mean ± Standard deviation”

Proportional p

0.065 0.157 0.382 0.410 0.066 0.531

Table 3. Mean ± standard deviation, median, minimum, maximum values of ITI values of pre- n=29].

p

0.160

, median, minimum, maximum values of pre- and post- fatigue simple and complex VRT measurements, and their levels of significance [n=29].

p

0.07

<0.05

, complex visual reaction [n = 29] axis is defined for FTT, SVRT and CVRT, and the second vertical

0.05, n = 29]

and success during those activities as well as to

Aydin et al.; BJMMR, 15(7): 1-8, 2016; Article no.BJMMR.25893

surveys [14,15]. Therefore, developing new methods to evaluate the MF state with high reliability and specificity has attracted the attention of researchers. Most studies have attempted to define new scales for MF by evaluating survey/scale results, together with the correlations of electrophysiological vital functions and motor and cognitive functions in MF produced by different models. Washer et al. [27] suggested that alpha waves rapidly became dominant in the electroencephalogram [EEG] power spectrum during the first hour of a 4-hour mental task. The authors emphasized increased error rate along with theta wave dominance in prolonged mental tasks and hypothesized that this characteristic change might be used as a criterion for MF. Zhao et al. [32] investigated a MF model using a driving simulation for 90 min and suggested that special alterations in the EEG power spectrum, an increased amplitude of the P300 wave in event-related potential and alterations in heart rhythm could be used as objective measure/criteria for MF. Tanaka et al. [12] observed neuronal activity using magnetoencephalography [MEG] during a 10-min continuous attention task and measured subjective findings of MF using the Visual Analog Scale [VAS] after the task. They quantitatively showed that VAS alone might not be sufficient for determining MF using MEG. The above-mentioned studies indicate that MF should be evaluated qualitatively using highly technological methods in addition to subjective methods. However, the aforementioned methods cannot be used in every setting and condition. Therefore, determining MF using simpler, easier-to-use and low-cost methods is important. Mental activities such as attention, understanding, association, interpretation and memorizing can cause MF in students during their daily educational activities [26]. However, in this study PFS indicated that a 4-hour daily educational activity did not cause MF after the fatigue model we applied. Conversely, the absence of any significant differences between pre- and post-fatigue FTT suggests that this mental activity also did not cause any motor fatigue in the students. The insignificant change in pre- and post-fatigue simple VRT tests performed to evaluate MF quantitatively using reaction time is in accordance with the results of Lagner et al. [33], who did not find any correlation between MF and “forewarned” simple VRT using a temporal preparation and suggested that VRT could not be used as a sensitive or indicative test for MF. All the aforementioned studies indicate that frequently used scales/surveys as well as the

methods that assess simple mental tasks may not be sufficient to evaluate MF under all circumstances. Our study indicated that participants were able to perform simple mental tasks after the fatigue model; however, they experienced difficulties in completing more complex mental tasks requiring cognitive processes.

The PFS has been accepted as a reliable method to determine motor/physical fatigue [34]. Although we have small number of participants, this study may suggest that borderline MF could not be determined by the PFS alone might be accomplished by complex VRT. This result is consistent with the results in studies using highly technological methods, and we suggest that complex VRT may be used as a supplementary method with abstract methods such as PFS. We hypothesize that wide use of tests such as complex VRT, which can be performed in every domain within a short time without expert support using personal computers or even smart phones, will be beneficial for educational planning, avoiding accidents and evaluating related diseases.

5. CONCLUSION

This study suggests that complex VRT test is a simple and reliable tool in determining borderline mental fatigue. Therefore, it may be beneficial for educational planning, avoiding accidents and evaluating related diseases.

CONSENT

All authors declare that ‘written informed consent was obtained from the patient [or other approved parties] for publication of this paper and accompanying images.

ETHICAL APPROVAL

All authors hereby declare that all experiments have been examined and approved by the appropriate ethics committee and have therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki.

ACKNOWLEDGEMENTS

COMPETING INTERESTS

Authors have declared that no competing interests exist.

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