Neurosyphilis has been called “the great imitator” because of its atypical clinical presentation ranging from motor dysfunctions to psychotic episodes to dementia. This, and the fact that it has become a rare disease, makes diagnosis challenging.

This work will present three early onset Major Neurocognitive Disorder cases for which neurosyphilis was considered as a possible cause.

In this presentation, we underline clinical characteristics that should raise the suspicion of neurosyphilis and the importance of an adequate diagnosis.

The three patients presented as case-reports were admitted to an acute psychiatric ward, presenting with psychomotor agitation and aggression. The initial clinical evaluation (including the patient's medical history) did not suggest the presence of syphilis. Subsequent blood-tests were performed, including RPR (Rapid Plasma Reagin) or VDRL (Venereal Disease Research Laboratory) which were positive in all three cases. Other tests were performed in order to confirm the presence of neurosyphilis.

All three patients had positive treponemal and nontreponemal test results. For only one of the three patients, imagistic abnormalities of the brain were present. For two of the patients, a positive diagnosis of Major Neurocognitive Disorder due to neurosyphilis was established.

Neurosyphilis can be a cause for Major Neurocognitive Disorder. The diagnosis of this pathology is important because cognitive function can be improved by adequate treatment.

The authors have not supplied their declaration of competing interest.