Since you at least dropped the crossposting, I'll give you a response.

Infections can cause some incidents of arthritis.
Infections can cause some incidents of dementia.

But not all.  The credibility of the doctor whose article you posted was
harmed in my view by his claim that infection-cause reactive arthritis was
the most common cause of arthritis; some quick Google searching turned up
research from a number of reputable sources for numbers showing that
osteoarthritis and rheumatoid arthritis are far more common (I haven't gone
back and looked today, and didn't make note of the exact figure, but as best
I can recall the incidences were something like 5-8% of the population
develop osteoarthritis, 3-5% rheumatoid arthritis, and only about 0.07% get
reactive arthritis).  Osteoarthritis and rheumatoid arthritis are not caused
by infection (in some few cases, an infection may act as a 'trigger' for RA,
but that's not the same as causing it).

The online searching I did turned up a distinct characteristic of reactive
arthritis: it strikes younger people on average than the types of arthritis
not caused by infectious agents.  Known infection-related dementia (most
commonly found in people with AIDS and otherwise suppressed immune function)
has a similar distinction: it affects younger people.

Now, since there's not an identifiable, testable infectious agent you're
offering as the cause of this alleged infectious Alzheimers, that is, no
case of a culture sample taken from AD patients that invariably turns up
positive , and no case study of  AD patients (as opposed to people with
distinctly other dementias) responding to antibiotic treatment (though
elderly AD patients are, I'd venture, probably given antibiotics more
frequently than their non-AD  counterparts, as they're often being closely
monitored for their health by others, perhaps given antibiotics when some
other infection is just suspected or possible, since they're often unable to
report their symptoms clearly).

All you can offer is guesswork -
Whereas: infections cause some diseases, including some dementia;
Therefore: infection causes Alzheimers dementia.

The tie-in to reactive arthritis really weakens the argument:  Alzheimers
lacks the distinctive characteristic  of reactive arthritis - affecting
relatively younger patients.  Alzheimers, in its demographic distribution,
is more similar to osteo- and rheumatoid arthritis, which, as we've already
noted, are not cause by infection.  AD is a disease overwhelmingly of the
elderly; infectious reactive arthritis is, distinctly from other types of
arthritis, a disease striking younger patients.

So, I really didn't see anything but speculation, and speculation that
doesn't follow logically from the comparisons offered.  I looked at your
presentation skeptically but openly, did some research on my own and as a
result found your hypothesis unpersuasive.

Finally, your demand that people who don't agree with the medical theory
you're proposing just ignore you and not call you on it is not a reasonable
one. First of all, your posts did have all the hallmarks of the common
crackpot quackery we see so often - cross-posted to every remotely
health-related newsgroup under the sun; espousing a virtual panacea (one
cure for a myriad of diseases); extrapolations of one medical theory tying
everything together in ways that were tenuous at best; and the opening line
about 'soon the truth will come out' that hints at a moribund medical
Establishment overlooking the brilliant and courageous work of one lone
research genius - which makes for a really good 1930s medical drama, but
isn't the way things really are.  And when a post about some novel medical
'theory' quacks like a duck, as the saying goes, it really is not
responsible for people who recognize the quacking to not say so.  Not when a
group like this is filled with newcomers often desperate for hope for a
tragic disease, people who may be persuaded by claims of cures that just
don't hold water and as a result follow treatments that at best waste time
better spent on medically sound treatment and at worst may cause more harm.

All I've got to say on the subject.

--
Robert