Diagnosis
The reduction in the patient’s antipsychotic therapy had caused behavioral disturbance and it was therefore reinstated Clozapine therapy was considered but not instituted.

An investigation administering DaTSCAN was carried out (shown above). This was markedly abnormal.

Low dose levodopa was instituted and the patient’s parkinsonian features reduced and his psychosis remained stable.

Final diagnosis: Parkinson’s disease unmasked by a neuroleptic drug.