may arise as a result of drug interactions, and/or concurrent damage or alteration of other brain structures, that may be unique to ones particular manifestation of PD symptoms.
Drug interaction hallucinations usually occur in PWP who take several classes of medication. A notorious one are opioid pain relief medication, but the halliucinations seem to be limited in their severity, to such things as "waking dreams". Coupled with high dopa dosing, one is asking for trouble.
Anti depressants can often be totally contraindicated, as the Serotonin transporter is another source of problematical and more profound hallucinations. Parietal lobe changes can also be a source of hallucinations. And hallucinations aren't limited to seeing people that aren't here. There are auditory ( and other sensual) hallucinations that can run from hearing a constant indecipherable noise, to full blown voices. This is a more serious situation because it has been postulated that around 30 percent of PWP, may end up with a dementia syndrome that makesPD all that much more troublesome to deal with. So try dumping medication that is not necessary, or can be replaced. Dopamine agonists are known to directly cause hallucinations , as is sinemet itself . Hope this says something. Cs