A twelve-year longitudinal study of neuropsychological function in non-saturation professional divers.

OBJECTIVES: Our main aim was to study the long-term neuropsychological effects of non-saturation diving. Further, we aimed to investigate whether neuropsychological performance was predictive of subsequent diving accidents and diving status.

METHODS: In this prospective longitudinal study, we enrolled 50 male diving students (mean age 25.3 years) at a diving school and followed them up six and 12 years later (43 and 37 divers, respectively). At each wave of the study, divers completed a comprehensive neuropsychological test battery and answered questionnaires on cumulative number of dives, incidents of decompression illness (DCI) and professional diver status.

RESULTS: At the 12-year follow-up, the divers reported a median number of 455 (range 40-5,604) cumulative dives. Cumulative number of dives was not associated with any adverse neuropsychological effects. However, divers with an incident of DCI performed worse in a memory test (Benton Visual Retention Test) and reported slightly more neuropsychiatric symptoms (Q 16). Diver students who performed well on a blindfolded memory test (tactual performance test) had an increased likelihood of becoming a professional diver 12 years later.

CONCLUSIONS: The main findings in the present study support the view that asymptomatic non-saturation divers who have dived under controlled conditions do not have an increased risk of impaired nervous system function, at least not to an extent that can be detected with neuropsychological tests while they still are relatively young. The observed associations between a history of DCI and impaired results in a memory test and reporting of neuropsychiatric symptoms may be due to a nervous system effect caused by DCI. The diver students' ability of problem-solving while they were blindfolded was predictive of their likelihood of becoming a professional diver 12 years later.