Did Van Gogh Have Syphilis?

It's generally assumed that Vincent Van Gogh had syphilis because (quite frankly) 10% of all European men had it in the late 1800s.  He was diagnosed with another sexually transmitted disease, gonorrhea, in 1882.  Both STDs have similar symptoms so Van Gogh could have been misdiagnosed.

Van Gogh is thought to have had syphilis for 2 reasons:

1. He frequented brothels
2. He was kinda loopy

According to Van Gogh:The Life (Random House; 2012) Van Gogh did have syphilis about 1885.  During this time he had terrible mouth sores and lost a lot of weight because he was unable to eat. (See p. 447)

Unlike gonorrhea, syphilis caused insanity (or seeming insanity) in it's last stages, called neurosyphilis.  In teriary syphilis, the face become deformed, as seen in the bust of such a patient (pictured.)

According to The Lobotomist John Wiley & Sons; 2005), one fifth of all patients in American psychiatric wards had syphilis in the 1920s and 1930s.  The book, a biography of lobotomist Walter Freeman, includes some really vivid passages describing neurosyphilis patients, such as this little gem from page 59:

Though largely forgotten today, neurosyphilis was a terrible disease, a near epidemic that left its targets -- mainly men thirty and over -- in a wasted, twisted condition, riddled with bedsores and unable to speak coherently...They frequently grew demented, demented, incontinent and unable to control their muscles.
 

The problem is that Van Gogh was not really old enough to begin showing symptoms of neurosyphilis.  Men usually begin showing them 10 to 20 years after they get infected. 

My theory (and I think I'm alone on this one) that Van Gogh thought he had syphilis.  Since he had spent time in asylums, he saw what happened to men suffering in the final stages of neurosyphilis.  Perhaps one of the deciding factors in his suicide was that he feared developing those horrible final symptoms.