The suggestion that Alzheimer’s may be a transmissible disease, and the reluctance of government science advisers to countenance the idea, has parallels with what happened over “mad cow” disease in the late 1980s and early 1990s.
At the time, science advisers to the government took the cautious approach that there was “no evidence” mad cow disease was a threat to human health, although they privately admitted that did not mean there was “no risk”.
The “no evidence” line is similar to that adopted by the Department of Health in relation to the possible transmission of Alzheimer’s disease.
In 1990, before scientists were able to confirm beyond doubt that bovine spongiform encephalopathy (BSE) had indeed jumped the “species barrier” from cows to humans, the then-chief medical officer, Sir Donald Acheson, was asked about the risk to the public of eating beef.
“There is no risk associated with eating British beef and everyone – children, adults, patients in hospital – can be quite confident with the safety of beef,” Sir Donald said in a television interview.
In 1998, two years after the first cases of “BSE in humans” appeared in the guise of variant Creutzfeldt-Jakob Disease (vCJD), Sir Donald told the public inquiry into the scandal that he should have stuck to the more cautious line that there was “no justification for not eating British beef” given that there was a remote risk, rather than no risk.
In relation to the risk of Alzheimer’s disease being transmissible, Dame Sally Davies, the current chief medical officer, has said: “There is no evidence that Alzheimer’s disease can be transmitted in humans, nor is there any evidence that Alzheimer’s disease can be transmitted through any medical procedure.”