Skepticism about science and medicine

In search of disinterested science

60 MINUTES on aging — correlations or causes?

Posted by Henry Bauer on 2014/05/06

The TV program 60 Minutes on 4 May 2014 reported on studies of people older than 90, for clues to what allowed them to live so long. It was clear that neither the reporters nor the doctors understand the difference between correlations and causes.

Dementia was a prime concern, Alzheimer’s in particular. The mainstream dogma was taken for granted, that Alzheimer’s is defined and caused by amyloid plaques and tangles in the brain.
It turns out, however, that behavioral dementia does not correlate with either of those: people showing no behavioral signs of Alzheimer’s might have quite a lot of tangles and plaques, while people with behavioral dementia might have little or none of either or both.
One doctor did at one point say that one possibility might be that the tangles were not causes of dementia, but no one questioned that amyloid defined Alzheimer’s despite the rather clear evidence that they are not correlated.
Lack of correlation is a good sign of lack of causation. If plaques and tangles cause Alzheimer’s dementia, then they should be present in all cases of AD. They are not. Yet the belief persists despite disproof.

At the same time, the misguided view that correlation indicates causation pervaded the program. It was said that maintaining weight or even gaining a bit made for — is a cause of, in other words — longevity; that vitamin supplements do not; that moderate alcohol and coffee intakes make for longevity, as does exercise and social activity.
BUT: Assume just for the sake of argument that healthy longevity is determined solely by genetics. Then exactly the same correlations would be observed. People with good genes would live longer, socialize more, exercise more, eat and drink with fewer restrictions . . . .
So those correlations in themselves say absolutely nothing about what might have actually caused the long healthy lives of the studied people.
Correlations never prove causation.

Some autopsies revealed that dementia and death were sometimes associated with signs of numerous mini-strokes that might have been so slight as to be not even noticed. The prevalence of such strokes was less in people with higher blood pressure, the opposite of expectation based on current medical dogma.
The lack of correlation between high blood pressure and stroke indicates, of course, that high blood pressure may not be a significant cause of stroke, but this conclusion was not drawn.

The chief doctor in the program was quick to add that high blood pressure is still a risk factor for younger people, showing ignorance of actual data and brainwashing by contemporary medical dogma and shibboleths. It’s been known for a century that blood pressure increases with age — normally, naturally. That people over 90 have “high” pressure should not have been a surprise, nor that they had fewer strokes: IF one lives to a significantly old age, it means that one has not had too many strokes, and living that long means that one’s blood pressure will naturally, normally, be what is nowadays called, out of ignorance, “high”.

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