Association between Shift Work and Neurocognitive Function among Firefighters in South Korea: A Prospective before–after Study

Abstract

Background: Recent research indicates that shift work is associated with neurocognitive function. However, studies that examine the association between shift work and neurocognitive function in firefighters have not yet been performed. We examined the effect of shift work on neurocognitive function in firefighters by measuring and comparing neurocognitive function before and after night shift. Methods: 352 firefighters from eight fire stations in South Korea were included in this study. We performed neurocognitive function test using central nervous system vital signs (CNSVS) during daytime work and on the next day after night work. We performed paired t-tests to assess differences between neurocognitive function before and after night work. We also compared neurocognitive function in insomnia and depression. We used a general linear model to analyze the associations between shiftwork schedule and the changes in neurocognitive function. Results: The neurocognitive function significantly decreased in six domains (composite memory, verbal memory, visual memory, complex attention, psychomotor speed, and motor speed) as did the neurocognitive index on the next day after night work compared with during day work. These decreased domains were the same following night work regardless of the type of shift work. Conclusion: Night work in firefighters may cause neurocognitive decline.

Repeat measures of DNA methylation in an inception cohort of firefighters

“…Cardiac events are also a leading cause of death in firefighters, 30 consistent with the identification of enriched pathways involving cardiovascular disease. There is also evidence that firefighter exposures such as shift work could lead to neurocognitive decline, 31 consistent with the findings of the current study involving enriched gene pathways for neurological functions.…”

Impact of Shift Work and Long Working Hours on Worker Cognitive Functions: Current Evidence and Future Research Needs

“…Moreover, in some studies, electrophysiological measures by electroencephalography and the determination in biological matrices of different hormones such as growth hormone (GH), cortisol and its precursors, prolactin (PRL), thyroid-stimulating hormone (TSH) and melatonin were also carried out in order to analyze the possible physio-pathological mechanisms underlying the observed alterations of cognitive domains. Importantly, in these studies, the potential role of different parameters that are recognized risk factors for the cognitive decline (e.g., age, family history for dementia and/or related diseases, hypertension, cerebral vasculopathies, metabolic syndrome, disorders of sleep and mood, physical inactivity, social isolation, lower education level and psychosocial factors) and that could represent confounding factors in the interpretation of the results have been often verified, albeit in quite different ways and combinations [ 7 , 8 , 21 , 25 , 26 , 27 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ]. Finally, most of the articles have studied the short-term effects of shift work, while few studies have analyzed the possible impact of long-term chronic exposure on cognition [ 27 , 31 , 46 , 47 , 48 , 49 , 50 , ...…”

“…Deterioration of cognitive efficiency following extended shifts work was also proved in paramedics and firefighters who worked 12 h and 24 h shifts, respectively [ 56 ]. Similarly, the cognitive efficiency of firefighters (assigned to different rotations of extended 15 and 24 h work shifts, including night) was significantly affected by the exposure to night work that was associated with lower scores of composite memory, verbal and visual memory, complex attention, psychomotor and motor speed [ 26 ].…”

“…In this regard, recent numerous studies suggested that shift work (particularly that including working at night) and in some cases also long working hours (that is working 41 or more hours per week) are able to cause important modifications of cognitive functions [ 21 , 25 , 26 , 27 ]. In detail, both qualitative and quantitative sleep disturbances (insomnia, shortened sleep, frequent sleep interruptions, irregular sleep cycle) associated with the shift work would induce a circadian rhythm misalignment which, in turn, activating neuroendocrine system and affecting specific brain areas would be ultimately responsible for the observed cognitive impairment [ 19 , 25 , 28 ].…”

The Development of a Sleep Intervention for Firefighters: The FIT-IN (Firefighter’s Therapy for Insomnia and Nightmares) Study

“…This study was conducted as part of the sleep panel study (SLEPS) to improve sleep disturbance in Korean firefighters [ 36 , 37 ]. This study was conducted as part of a larger 7-year sleep panel study (SLEPS) to improve sleep disturbance in Korean firefighters [ 36 , 37 ]. The purpose of SLEPS was to investigate sleep disturbance among Korean firefighters and develop and investigate the efficacy of a sleep intervention program, with the final goal of nationwide dissemination.…”