THE NEUROPSYCHIATRIC SEQUELAE OF MERCURY-POISONING - THE MAD-HATTERS-DISEASE REVISITED

Background. The detailed effects of mercury poisoning on cognitive fun ction, brain anatomy and regional brain function are largely unknown. We report the case of a 38-year-old man who was exposed to toxic level s of inorganic mercury. Method. Four years after exposure, the patient was assessed using magnetic resonance imaging (MRI), single-photon em ission computerised tomography (SPECT) and detailed neuropsychological evaluation. Results. The patient developed a myriad of physical and p sychiatric complaints, including stomatitis, muscle spasm, tremor, ski n rash and the psychiatric syndrome known as 'erythism' (Mad Flatter's disease). Neuropsychological evaluation revealed marked and significa nt deficits of attention concentration, particularly when under time p ressure. The MRI scan was unremarkable; however, SPECT revealed hyperm etabolism of the posterior cingulate cortex. Conclusions. Mercury pois oning appeared to result in a dysregulation of posterior cingulate cor tex, which was associated with attention/concentration deficits and ma rked anxiety/agitation.