Via New Scientist, the bizarre, unintended side effect of a cold sore medication suggests that it may be possible to engineer a drug that induces the living-dead mental state:
Pharmacologists have discovered a mechanism that triggers Cotard’s syndrome – the mysterious condition that leaves people feeling like they, or parts of their body, no longer exist. With the ability to switch the so-called walking corpse syndrome on and off comes the prospect of new insights into consciousness.
Acyclovir – also known by the brand name Zovirax – is a common drug used to treat cold sores and other herpes infections. However, about 1 per cent of people who take the drug orally or intravenously experience some psychiatric side effects, including Cotard’s. These occur mainly in people who have renal failure.
One woman with renal failure began using acyclovir to treat shingles. She ran into a hospital screaming. After an hour of dialysis, she started to talk: she said the reason she was so anxious was that she had a strong feeling she was dead.
Blood analysis suggests an explanation. When someone takes acyclovir, it is broken down in the body before being removed via the kidneys. One of these breakdown products, CMMG, is usually found at very low levels. But those who had symptoms of Cotard’s had much higher levels. All but one of these eight people had renal failure.
There may be a genetic link between how people metabolise acyclovir and the symptoms they get. What’s fascinating is that there is now, in theory, a way to turn Cotard’s on and off.