The evidence seems to indicate that the electrical potentials are significantly lower, in other words, that there is a hard physical component to being burn-out.

I'm not sure that proves a "hard physical component" in the sense of which direction the causation goes. How else can mental activity take place except through some change in either electrical potentials, neurotransmitter release, physical configuration of the brain, or some other such "hard physical component"? There's really no other way for any mental characteristics to manifest themselves except through these physical mechanisms.

From what I know about it, and that's pretty limited, normally it is the frequency of excitation that determines neural activity, to find a lesser potential could indicate a chemical deficit of sorts.

So if this was just a psychological issue you would not expect to find this correlation with a physical value that is at first glance not directly related to the ability of the brain to think (which is the pre-requisite for being productive in the first place).

If thinking about stuff really is harder for people that are burned out because of an underlying physical cause it would explain a lot.

_delirium's contention is simply that all brain states (even those underlying "psychological issues") have physical bases and therefore we can (theoretically) measure them. The problem is that a set of brain states may have different "causes" -- and causation get's really tricky here but that's another story.

For example, the measured brain states associated with burn out could be do to a chemical deficiency (either in diet or genetic), or be because the person worked a long day at work, or perhaps could be a result of the person staying up very late playing video games. Most people would agree that the first is a disease state, but what about the second? The third?

Finally, with respect to their finding that burnout was associated with smaller potentials, assuming that they made their measurements using fMRI[1], then they were measuring changes in blood flow, which in turn are putatively reflective of the metabolic activity of nearby neurons, which in turn is putatively reflective of their frequency of excitation, averaged over some interval. There are circumstances where the magnitude of individual action potentials are affected, but I strongly doubt that is what they are talking about here, not the least because I don't see how they could measure it.

1. If they instead used EEG, I can make a similar argument that they are still measuring frequency of excitation.

Ok, that makes sense. But even if it does not rule it out there definitely is something going on here, which is why there will have to be some more study. The surprising thing to me is that they could find any evidence at all, instead of no differences between people with and without the burn-out symptoms.

After all for a variety of psychological disorders there is no objective difference between a 'healthy' and a 'diseased' brain that we can nail down, to find one in this instance is an indication that there might be some clear underlying cause.

As long as that cause has not been found it's somewhat speculative but my guess is that if they can nail it down so clearly that a cause will one day be found.