nineteenthcenturytxt3

During the nineteenth century, understanding was achieved that
microscopic organisms cause illness, including some that affect the
brain. Pasteur et al. (1884) determined by inoculation and transfer that
rabies (la rage) was caused by an infectious process. The book by
Dowse (1879) is an early argument in support of the idea that syphilitic
infection of the brain could account for aberrant states of mind, in
addition to dipsomania (alcohol dependence) and epilepsy. He viewed
three causes of paralysis with which syphilis could be confused,
embolism, thrombosis, or hemorrhage. But he noted, "The onset of
these is usually sudden and complete, whereas syphilis in its working is
slow, alternately progressive and retrogressive."

Citations to works on neurosyphilis are included in the bibliography and
this chronology of understanding because syphilis was one of the major
causes of mental illness (dementia paralytica) until effective treatment
with penicillin became available in 1943.

Because it is no longer common for syphilis to progress to the point
where it affects the nervous system, it is also instructive to look at the
data that was gathered in the past. For example Wood (1889) in
seventeen years experience at the Philadelphia Hospital saw about two
thousand patients suffering from various affections of the nervous
system, of whom more than fifty percent suffered from syphilis. Death
was inevitable in these cases and the brain lesions could be observed at
autopsy. Wood described two primary aspects of the brain pathology of
neurosyphilis: (1) a gummatous inflammation of the meningeal tissues
that probably commence in the sheath of the arterioles, and (2) a
disease of the blood vessels.

The gumma of syphilis are a form of scar tissue that builds up as an
immune reaction to the spirochete bacterium treponema pallidum.
Discovery of this micro-organism in the brain would not be made until
1913 (by Hideao Noguchi). Nevertheless Wood (1889) noted that
syphilis of the blood vessels in the brain (atheroma) were frequent, and
that one form of syphilitic disease was especially prone to attack the
arteries at the base of the brain. He found gummatous tumors frequently
in the pons and corpora quadrigeminae. We now know that these are
where brainstem nuclei of highest metabolic rate are found, especially in
auditory structures like the superior olive and inferior colliculus.

The discovery of the cause and search for a cure for syphilis is an
interesting story with relevance for mental illnesses that are still not well
understood and for which causes and cures remain to be discovered.
But does this have relevance for an understanding of autism spectrum
disorders? Dementia paralytica is part of the spectrum of psychotic
disorders now known as schizophrenia, and autism in previous decades
was viewed as schizophrenia of earliest childhood.