title: Negative neurofunctional effects of frequency, depth and environment in recreational scuba diving: the Geneva "memory dive" study.
abstract: OBJECTIVE
  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 (133)Xe 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.
authors.affiliation: Division of Nuclear Medicine, Geneva University Hospital, Geneva, Switzerland. slosman@medecine.unige.ch
authors.forename: D O
authors.initials: DO
authors.lastname: Slosman
authors.forename: S
authors.initials: S
authors.lastname: De Ribaupierre
authors.forename: C
authors.initials: C
authors.lastname: Chicherio
authors.forename: C
authors.initials: C
authors.lastname: Ludwig
authors.forename: M-L
authors.initials: ML
authors.lastname: Montandon
authors.forename: M
authors.initials: M
authors.lastname: Allaoua
authors.forename: L
authors.initials: L
authors.lastname: Genton
authors.forename: C
authors.initials: C
authors.lastname: Pichard
authors.forename: A
authors.initials: A
authors.lastname: Grousset
authors.forename: E
authors.initials: E
authors.lastname: Mayer
authors.forename: J-M
authors.initials: JM
authors.lastname: Annoni
authors.forename: A
authors.initials: A
authors.lastname: De Ribaupierre
mesh_terms: D000328:Adult; D000886:Anthropometry; D001921:Brain / Q000000981:diagnostic imaging; D002560:Cerebrovascular Circulation; D003072:Cognition Disorders / Q000209:etiology*; D003080:Cold Temperature / Q000009:adverse effects; D004242:Diving / Q000009:adverse effects* / Q000502:physiology / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011446:Prospective Studies; D011594:Psychometrics; D015899:Tomography, Emission-Computed, Single-Photon