Diving brain damage risk reinforced

Scuba diving could be bad for your health

A study has found more evidence that divers are risking brain damage when they go underwater.

A few researchers have noticed higher numbers of areas of damaged brain tissue, or lesions, in divers.

But the new survey suggests that going scuba diving increases the risk of developing one or more lesions by as much as five times.

Dr Christian Seiler, from the University of Bern in Switzerland, took magnetic resonance imaging (MRI) scans of the brains of 52 divers and the same number of non-divers.

He found that in 19 of the divers, there were a total of 41 brain lesions, compared to just seven lesions in only six of the non-divers.

He said: "Diving increased the incidence of one or more ischaemic brain lesions by five-fold."

The affected divers had not performed any more, or any deeper dives than unaffected divers, and did not seem to be linked to smoking, or alcohol or medication use.

Heart defect

In addition, the study seemed to confirm the suspicion that divers suffering from a heart defect called a patent foramen ovale were more susceptible to this subtle damage.

A patent foramen ovale is an opening between two chambers of the heart which would in the majority of people have closed shortly after birth. If the opening remains, it affects the efficiency of blood pumping through the heart.

The study, published in the Annals of Internal Medicine, confirms another possible danger to divers, although it does not explain exactly why the damage may be occurring.

There are three possibilities, the first of which is decompression sickness, in which bubbles of gas either form in or invade the blood stream, and can cause small areas of tissue to become starved of oxygen and die.

Other possibilities are oxygen starvation, or anoxia, caused by near-drowning, or the toxic effects of breathing gases given at higher than atmospheric pressure.

The bends

Decompression sickness - or "the bends" is perhaps one of the most feared medical risks associated with diving.

Ascending too rapidly to the surface at the end of a dive can cause large numbers of gas bubbles to form in the bloodstream because of the change in pressure.

If one stops the blood flow to part of the lungs, the result can be a life-threatening pulmonary embolism.

However, sometimes the effects may be very mild, with relatively minor neurological problems such as vague confusion or slightly blurred vision, for which a diver may not even seek medical attention, as they often wear off quickly.

Some doctors have suggested that minor brain damage such as the lesions spotted in these scans may occur on occasions like this.