Sex and stress can make you lose your memory

I HAVE just returned from Cornwall, where I went swimming in the sea. Although I love doing this, I was a little bit anxious because last summer I had been out swimming with my wife, Clare, when everything went blank. The next thing I remember was being in A&E, with Clare sitting beside me looking extremely concerned.

Apparently, when I emerged from the water, I looked very confused and kept asking her: ‘Where am I? ’

Fortunately, I was seen by a smart doctor who explained that I had experienced a rare problem called TGA, transient global amnesia, which badly affects memory. But he fully expected it to return to normal. Which it did.

I later asked Dr Paul Jarman, a consultant at the National Hospital for Neurology and Neurosurgery in London — and one of the experts in my recent BBC series, The Diagnosis Detectives (still available on iPlayer!), to explain what had gone wrong. He told me that TGA is often triggered by cold-water swimming, vigorous exercise, sex or being under extreme stress. These can all lead to a type of breathing known as the Valsalva manoeuvre, where you hold your breath while trying to forcefully exhale. This in turn can cause a swelling in blood vessels around the hippocampus, an area of the brain linked to memory storage.

‘Over the next couple of hours the blood flow returns to normal,’ he says. ‘The hippocampus begins to function again. But no matter how hard you try, you’ll never recall what happened during that time because your brain simply didn’t store any information.’

I’m glad to say the only surprising thing during my most recent swim was a seal surfacing and circling us for a few minutes before disappearing.