Such reports that paranoia seemed to appear more in older patients who had experienced higher levels of discrimination throughout their lives. In addition to this it has been noted that immigrants are quite susceptible to forms of psychosis. This could be due to the aforementioned effects of discriminatory events and humiliation. Psychological
Many more mood-based symptoms, grandiosity and guilt, may underlie functional paranoia.Colby (1981) defined paranoid cognition in terms of persecutory delusions and false beliefs whose propositional content clusters around ideas of being harassed, threatened, harmed, subjugated, persecuted, accused, mistreated, wronged, tormented, disparaged, vilified, and so on, by malevolent others, either specific individuals or groups (p. 518). Three components of paranoid cognition have been identified by Robins & Post: a) suspicions without enough basis that others are exploiting, harming, or deceiving them; b) preoccupation with unjustified doubts about the loyalty, or trustworthiness, of friends or associates; c) reluctance to confide in others because of unwarranted fear that the information will be used maliciously against them (1997, p. 3). Paranoid cognition has been conceptualized by clinical psychology almost exclusively in terms of psychodynamic constructs and dispositional variables. From this point of view, paranoid cognition is a manifestation of an intra-psychic conflict or disturbance. For instance, Colby (1981) suggested that the biases of blaming others for ones problems serve to alleviate the distress produced by the feeling of being humiliated, and helps to repudiate the belief that the self is to blame for such incompetence.
This intra-psychic perspective emphasizes that the cause of paranoid cognitions is inside the head of the people (social perceiver), and dismisses the possibility that paranoid cognition may be related to the social context in which such cognitions are embedded. This point is extremely relevant because when origins of distrust and suspicion (two components of paranoid cognition) are studied many researchers have accentuated the importance of social interaction, particularly when social interaction has gone awry. Even more, a model of trust development pointed out that trust increases or decreases as a function of the cumulative history of interaction between two or more persons.Another relevant difference can be discerned among "pathological and non-pathological forms of trust and distrust". According to Deutsch, the main difference is that non-pathological forms are flexible and responsive to changing circumstances. Pathological forms reflect exaggerated perceptual biases and judgmental predispositions that can arise and perpetuate them, are reflexively caused errors similar to a self-fulfilling prophecy. It has been suggested that a "hierarchy" of paranoia exists, extending from mild social evaluative concerns, through ideas of social reference, to persecutory beliefs concerning mild, moderate, and severe threats. Physical
A paranoid reaction may be caused from a decline in brain circulation as a result of high blood pressure or hardening of the arterial walls.Drug-induced paranoia, associated with cannabis, amphetamines, methamphetamine and similar stimulants has much in common with schizophrenic paranoia; the relationship has been under investigation since 2012. Drug-induced paranoia has a better prognosis than schizophrenic paranoia once the drug has been removed.