Snippets from the Research world – Don’t gamble at depth: nitrogen narcosis and decision making

Decision making in scuba diving is a critical skill that can mean the difference between a safe dive and a dangerous situation.

As divers descend they must navigate a complex environment where multiple split-second judgments can have significant consequences. In challenging situations divers must remain calm and focused, using problem-solving skills to address unexpected obstacles.  Decision making is critical.

While gas narcosis is often experienced by divers beyond 30m the significance of its effects remain poorly understood.  Dives to 30m or shallower are often considered safe from risks from nitrogen narcosis due the lack of noticeable effects, but both DAN and BSAC incident reports have previously cited nitrogen narcosis as a factor at depths from 20m+, often due to impaired capacity to respond to an issue underwater.

In a recent issue of Diving and Hyperbaric Medicine, Pauliina Ahti and Jan Wikren report an interesting study of divers at 30m on air using the widely used and validated Iowa Gambling Task (IGT) as a measure of impairments in decision making.

The tool was originally developed and validated to predict real-life decision deficits. In their study the IGT measure was undertaken using an underwater tablet by a group at 30m with an equivalent group undertaking the same tasks at 5m as a control.

Although the groups were small, the results suggested that nitrogen narcosis potentially affects decision making at 30m through altering higher cognitive functions in the brain.  So nitrogen narcosis may be more than it seems, and higher brain functions may be affected long before the diver is aware of any deficit.

Further research will show whether these deficits can be measured at less than 30m and at what depth the effects are first measurable.

Ahti PA, Wikgren J. Rapture of the deep: gas narcosis may impair decision-making in scuba divers.  Diving and Hyperbaric Medicine. 2023 December 20;53(4):306−312. doi: 10.28920/dhm53.4.306-312. PMID: 38091589.