Persons with delusional disorder may suspect others of participating in elaborate master plots to persecute them. They believe that they are being poisoned, drugged, spied upon, or are the targets of conspiracies to ruin their reputations or even to kill them. They sometimes engage in litigation in an attempt to redress imagined injustices. An unmistakable sign of paranoia is continual mistrust. People with paranoid personality disorder are constantly on their guard because they see the world as a threatening place. They tend to confirm their expectations by latching on to any speck of evidence that supports their suspicions and ignore or misinterpret any evidence to the contrary. They are ever watchful and may look around for signs of a threat.
Because persons with paranoid personality disorder are hyperalert, they notice any slight and may take offense where none is intended. As a result, they tend to be defensive and antagonistic. When they are at fault, they cannot accept blame, not even mild criticism. Yet they are highly critical of others.
Persons with grandiose delusions often feel that they have been endowed with special powers and that, if allowed to exercise these powers, they could cure diseases, banish poverty, ensure world peace, or perform other extraordinary feats.