Which clinical characteristic is most associated with late syphilis?

Late syphilis, particularly in its tertiary stage, is often characterized by specific neurological findings. One hallmark of this stage is the presence of Argyll Robertson pupils. These pupils are typically small, irregular, and respond poorly to light but constrict well during accommodation. This unique pupillary response is a classic sign associated with neurosyphilis, indicating central nervous system involvement.

In the context of the other options, while hemiparesis can occur due to various neurological disorders, it is not specifically tied to late syphilis. Memory impairment may be seen in several conditions as well, including dementias or other neurodegenerative disorders, but does not have a direct association with late syphilis. Delusional disorder pertains to a specific type of psychotic disorder and is not directly linked to syphilis or its stages.

Thus, Argyll Robertson pupils stand out as the most specific clinical characteristic associated with late syphilis due to their distinct physiological response and indication of neurological compromise related to the infection.