[modeless]

All of the Alzheimer's patients were 79 or older, while all of the control patients were younger than 79 except for one. More than half of the control patients were under 60. That doesn't seem like a very good control to me.

[3327]

Perhaps but the discovery is still significant. Until now there was no such correlation with Alzeimher's and Fungi.

This has significant implications in terms of direction of future research.

[dragonwriter]

> Until now there was no such correlation with Alzeimher's and Fungi.

The point of the criticism seems to be that with an improper control group, there still isn't such a correlation, just a suggestion of a possibility of a correlation. But it might be a correlation between, e.g., age and fungal infection.

That's why, but for the variables under study, you want your control group to look as much like your experimental group as possible.

[philipov]

A general correlation between age and fungal infection might be even more significant, since that suggests a path to reduce the effects of aging in general. Either way, a follow-up study to remove those control flaws and hone in on the cause would be necessary.

[nickff]

Even with an improper control group, the fungi-Alzheimer's correlation still exists. There may be another factor which is causing the correlation (a so-called 'dreaded third thing'), and the correlation may not indicate causation, but the correlation still exists.

[Dylan16807]

That's not how correlations work.

[calinet6]

That is how correlations may not work, though.

[zeckalpha]

The improper control means that there is a just as strong of a correlation between age and fungi.