Decreased low-frequency brain effective connectivity in seafarers during voyages: a functional near-infrared...

During voyages, seafarers experience psychological problems that act to decrease operational safety. Psychological problems in seafarers can lead to changes in functional brain networks. This study investigated the low-frequency brain effective connectivity (EC) in seafarers during voyages by using the coupling strength (CS) of functional near-infrared spectroscopy (fNIRS) imaging.

This study recruited 15 seafarers (seafarer group) working on a container ship and 15 healthy age-matched controls (control group). The EC was assessed using dynamic Bayesian inference (DBI) of the oxygenated hemoglobin concentration (delta HbO₂) as measured through a 14-channel fNIRS system. These channels covered the left and right prefrontal cortices (LPFC/RPFC), left and right motor cortices (LMC/RMC), and left and right occipital lobes (LOL/ROL).

The EC levels of LPFC to RMC (F = 4.239, p = 0.049), LPFC to ROL (F = 5.385, p = 0.028), LOL to RPFC (F = 11.128, p = 0.002), ROL to RPFC (F = 10.714, p = 0.003) and LMC to ROL (F= 6.136, p = 0.02) were significantly lower in the seafarer group than in the control group. Correlation analysis revealed that the patient health questionnaire-9 (PHQ-9) scores were positively correlated with the systolic blood pressure (SBP) values, delta HbO₂ values and EC levels, respectively. Meanwhile, the correlation analysis revealed that the SBP values significantly positively correlated with the CS values.

Decreased EC levels may be a marker of psychological subhealth in seafarers. The approach combines fNIRS and PHQ-9 scores, providing a quantitative method for the assessment of mental health problems and further help with better rehabilitation designs in seafarers during voyages.