Almost half of Americans believe one medical conspiracy theory, says study

Is there really a link between vaccines and autism, or HIV and the CIA? Is the US Food and Drug Administration (FDA) covering up a cure for cancer?

Almost half of Americans believe the answer is yes for at least one of the many medical conspiracy theories that have circulated in recent years.

And the attitudes and behaviour of those conspiracists toward standard medical advice reflect that mistrust, says a study out this week.

A pair of University of Chicago social scientists set out to determine the extent of "medical conspiracism" among the US public and conducted a nationally representative online survey of 1,351 adults. They gauged knowledge of and beliefs about six widely discussed medical conspiracy theories and explored how belief in those theories influenced individuals' behaviour when it came to matters of health.

Their results appeared as a letter published online this week in the journal JAMA Internal Medicine. Fully 37 per cent of those surveyed endorsed the belief that the FDA, under pressure from pharmaceutical companies, is suppressing natural cures for cancer and other diseases, and 31 per cent said they "neither agree nor disagree" with that idea, the researchers found.

One in five of those surveyed said they agreed that physicians and the government "still want to vaccinate children even though they know these vaccines cause autism and other psychological disorders".

And 36 per cent were on the fence, saying they neither agreed nor disagreed that there may be truth in the much-studied and widely discredited contention that vaccines cause autism.