Original articleRelationship between cognitive functions and prevalence of fatigue in elementary and junior high school students
Introduction
Fatigue, defined as difficulty in initiating or sustaining voluntary activities [1], is common; up to 8% of children and adolescents have experienced fatigue for more than 1 month, and nearly 2% have experienced chronic fatigue lasting more than 6 months [2]. Since fatigue in students corresponds with a decrease in academic performance [3], clarification of the precise causes of fatigue and identification of ways to overcome fatigue are very important.
Morphological analyses in children and adolescents have shown that brain maturation occurs at different rates in different brain regions; the primary sensory and motor areas are the first to complete development, while the association areas, especially in the frontal and parietal regions, are the last to mature [4], [5]. Along with structural changes in the brain, executive function, defined as the set of mental control cognitive processes that permit goal-directed behavior, develops dramatically between childhood and adolescence [6]. In the field of development of executive function, for example, age-related gain has been reported in inhibitory control [7], working memory [8], [9], task switching [10], adaptive problem solving [11], and various other planning and problem solving tasks [12]. Executive function is also related to control of attention [13], an important element of information processing that is embodied in the central executive component in theoretical conceptions of working memory [14]. Attentional competency develops steadily through early and late childhood, perhaps due in part to the development of core processing resources [15]. Recently, we have been reported the differences of development of these cognitive functions between elementary school and junior high school students using paper-and-pencil and computerized cognitive function tests [16]; although performance of school students in motor processing task improved by grade in elementary school, they did not change from elementary school to junior high school. In contrast, performance of school students in spatial and non-spatial working memory, alternative and divided attention tasks improved from elementary to junior high school. In junior high school, performance of school students in divided attention improved by grade.
Childhood chronic fatigue syndrome (CCFS), characterized by profound and disabling fatigue persisting for at least 6 months [17], is a disorder model of severe fatigue in children and adolescents [18]. CCFS can severely impair cognitive functions such as learning, short-term memory, and attention processing [18], [19]. It seems that impaired cognitive functions are associated with fatigue. However, these findings were limited to a specific disease. The relationship between cognitive functions and fatigue in healthy elementary and junior high school students remains unclear. Knowing about these cognitive functions might help the education community to develop screening procedures to identify those at high risk of fatigue, and to conduct early interventions to achieve lower incidences of and higher rates of recovery from fatigue.
When students proceed to junior high school from elementary school, rapid changes in the environment occur, which may cause various behavioral and emotional problems [20]. One example is the number of Japanese students with school-refusal, which is 7483 out of 1,192,343 in 6th-graders and 22,566 out of 1,199,764 in 7th-graders in 2005 [21]. In addition, the prevalence of CCFS included in school-refusal increases from elementary school to junior high school, suggesting that fatigued students increase from elementary school to junior high school. In the present study, we therefore administered the paper-and-pencil and computerized cognitive function tests in particular focusing on grade-dependent development of cognitive function to 4th-, 5th-, and 6th-grade students in an elementary school and 7th-, 8th-, and 9th-grade students in a junior high school and investigated the relationship between cognitive functions and fatigue as derived from a questionnaire.
Section snippets
Subjects
Subjects were recruited from the 4th-, 5th-, and 6th-grades in an elementary school and from the 7th-, 8th-, and 9th-grades in a junior high school in Hyogo Prefecture. Most of the students at the elementary school were expected to proceed onto the junior high school. Forty-five subjects with medical illnesses, such as allergic disease, bronchial asthma, thyroid disease, nephritis, diabetes mellitus, heart disease, anemia, myodystrophy, and epilepsy, were excluded from the analyses. In
Results
The characteristics of the six grades (4th through 9th) analyzed are shown in Table 1. Fatigue score on the questionnaire and performance on the cognitive function tests in a total of 300 elementary school and junior high school students [148 elementary school students (79 girls and 69 boys) and 152 junior high school students (70 girls and 82 boys)] were analyzed.
Baseline characteristics of study subjects according to prevalence of fatigue are summarized in Table 2. The prevalence of fatigue
Discussion
These cross-sectional data demonstrate that reaction time on task D of the mATMT was associated with the prevalence of fatigue in elementary school students. In junior high school students, digit span forward test score, kana pick-out score, and reaction time on task E of the mATMT were associated with the prevalence of fatigue. These findings were independent of factors of grade and gender. To our knowledge, this study provides the first cross-sectional evidence to clarify the association
Acknowledgements
This work was supported by Japan Science and Technology Corporation/Research Institute of Science and Technology for Society. We would like to thank Dr. Chandler Gibbons for editorial help with the manuscript and Dr. Tetsumori Yamashima (Kanazawa University Graduate School of Medical Science) for providing permission and helpful comments on the use of some of the paper-and-pencil cognitive tests.
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