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BMJ Open. 2019 Jun 27;9(6):e026992. doi: 10.1136/bmjopen-2018-026992.

Sleep-Cognition Hypothesis In maritime Pilots, what is the effect of long-term work-related poor sleep on cognition and amyloid accumulation in healthy middle-aged maritime pilots: methodology of a case-control study.

Thomas J1,2,3, Ooms S1,2,3, Verbeek M2,3,4, Booij J5,6, Rijpkema M6, Kessels RPC2,3,7,8, Overeem S9,10, Claassen J1,2,3.

Author information

Geriatric Medicine, Radboudumc, Nijmegen, The Netherlands.
Radboud Alzheimer Center, Nijmegen, The Netherlands.
Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.
Neurology, Radboudumc, Nijmegen, The Netherlands.
Radiology and Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands.
Radiology and Nuclear Medicine, Radboudumc, Nijmegen, The Netherlands.
Vincent van Gogh Institute for Psychiatry, Venray, The Netherlands.
Medical Psychology, Radboudumc, Nijmegen, The Netherlands.
Eindhoven Medtech Innovation Center, Eindhoven University of Technology, Eindhoven, The Netherlands.
Sleep Medicine Center Kempenhaeghe, Heeze, The Netherlands.



Evidence indicates a bidirectional relationship between poor sleep and Alzheimer's disease (AD). While AD may lead to disruption of normal sleep, poor sleep in itself may play a causal role in the development of AD by influencing the production and/or clearance of the amyloid-beta (Aβ) protein. This led to the hypothesis that extended periods (>10 years) of sleep loss could lead to Aβ accumulation with subsequent cognitive AD-related decline. This manuscript describes the methodology of the SCHIP study, a cohort study in maritime pilots that aims at investigating the relationship between prolonged work-related sleep loss, cognitive function and amyloid accumulation among healthy middle-aged maritime pilots, to test the hypothesis that prolonged sleep loss increases the risk of AD-related cognitive decline.


Our study sample consists of a group of healthy middle-aged maritime pilots (n=20), who have been exposed to highly irregular work schedules for more than 15 years. The maritime pilots will be compared to a group of healthy, age and education-matched controls (n=20) with normal sleep. Participants will complete 10 days of actigraphy (Actiwatch 2, Philips Respironics) combined with a sleep-wake diary. They will undergo one night of polysomnography, followed by comprehensive assessment of cognitive function. Additionally, participants will undergo amyloid positron emission tomography-CT to measure brain amyloid accumulation and MRI to investigate atrophy and vascular changes.


All analyses will be performed using IBM SPSS V.20.0 (SPSS). We will perform independent samples t-tests to compare all outcome parameters.


The study protocol was approved by our institutional ethical review board (NL55712.091.16, file number 2016-2337) and will be performed according to Good Clinical Practice rules. Data and results will be published in 2020.


alzheimer’s disease; amyloid accumulation; cognitive function; neurodegeneration; sleep

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