ORIGINAL ARTICLE

Negative neurofunctional effects of frequency, depth and environment in recreational scuba diving: the Geneva "memory dive" study

D O Slosman¹, S de Ribaupierre¹, C Chicherio^1,2, C Ludwig^1,2, M-L Montandon¹, M Allaoua¹, L Genton^1,3, C Pichard³, A Grousset⁴, E Mayer⁵, J-M Annoni⁵, A de Ribaupierre²

¹ Division of Nuclear Medicine, Geneva University Hospital, Geneva, Switzerland
² Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland
³ Nutrition Unit, Geneva University Hospital, Geneva, Switzerland
⁴ Hopital Font-Pre, Toulon, France
⁵ Neurology Clinic, Geneva University Hospital, Geneva, Switzerland

Correspondence to:
Correspondence to:
D O Slosman
Geneva University Hospital, Division of Nuclear Medicine, Geneva, Switzerland; slosman{at}medecine.unige.ch

Objectives: To explore relationships between scuba diving activity, brain, and behaviour, and more specifically between global cerebral blood flow (CBF) or cognitive performance and total, annual, or last 6 months’ frequencies, for standard dives or dives performed below 40 m, in cold water or warm sea geographical environments.

Methods: A prospective cohort study was used to examine divers from diving clubs around Lac Léman and Geneva University Hospital. The subjects were 215 healthy recreational divers (diving with self-contained underwater breathing apparatus). Main outcome measures were: measurement of global CBF by ¹³³Xe SPECT (single photon emission computed tomography); psychometric and neuropsychological tests to assess perceptual-motor abilities, spatial discrimination, attentional resources, executive functioning, and memory; evaluation of scuba diving activity by questionnaire focusing on number and maximum depth of dives and geographical site of the diving activity (cold water v warm water); and body composition analyses (BMI).

Results: (1) A negative influence of depth of dives on CBF and its combined effect with BMI and age was found. (2) A specific diving environment (more than 80% of dives in lakes) had a negative effect on CBF. (3) Depth and number of dives had a negative influence on cognitive performance (speed, flexibility and inhibition processing in attentional tasks). (4) A negative effect of a specific diving environment on cognitive performance (flexibility and inhibition components) was found.

Conclusions: Scuba diving may have long-term negative neurofunctional effects when performed in extreme conditions, namely cold water, with more than 100 dives per year, and maximal depth below 40 m.

Keywords: BMI; cerebral perfusion; cognitive performance; scuba diving; SPECT; Xenon-133

Abbreviations: CBF, cerebral blood flow; DCS, decompression sickness; SPECT, single photon emission computed tomography

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