John Darwin’s apparent amnesia may have been caused by extreme stress – but forgetting a seven-year chunk would be “highly unusual”, an expert said yesterday.

Dr Eli Jaldow, consultant clinical neuropsychologist at the memory clinic at St Thomas’ Hospital, London, said: “Faced with unbearable stress, the brain just shuts down to protect itself when confronted.

“What is highly unusual is forgetting a circumscribed chunk of memory, you don’t often get a precise cut-off point, unless he is epileptic.

“It is also unusual, after five or seven years, for it all to come flooding back in one go, it usually happens in piecemeal fashion, bit by bit.”

Dr Jaldow said that the process of recovery was triggered by prompts, such as a familiar face. “It would be interesting to find out if he had a total loss of personal identification, not just

memory. If between 2000 and now he didn’t know who he was, did he adopt another personal identification?”

Dr Jaldow said that Mr Darwin’s father may have been right when he said that the amnesia was caused by a head injury when his son was five.

“There is evidence to suggest that a relatively mild brain injury can predispose people to memory loss later in life if there are other significant financial or emotional stresses.”

Dr Jaldow said that if Mr Darwin had forgotten everything that happened in the five-year period that he was missing and two years before that, he was likely to have problems learning and remembering any new information.

“It’s all very speculative, the only way to find out anything approaching the truth would be a full assessment.”

Doug Bruce, 35, a Briton living in New York, found himself on the subway in July 2003 with cuts and bruises on his head and no memory. He said that he was terrified as he went to police and told them: “I don’t remember who I am.”

Clive Wearing, a successful musician from London, has suffered amnesia since 1985, when he contracted encephalitis. The disease wiped almost all his knowledge of his past, but he is still able to recognise his wife Deborah.

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