Individuals with paranoid personality disorder tend to lead maladaptive lifestyles and might present as irritable, unpleasant, and emotionally guarded. Paranoid personality disorder is not a form of delusion, but is a pattern of habitual distrust of others.
The disorder generally is expressed verbally, and is seldom accompanied by hallucinations or unpredictable behavior. Distrust of others might result in social isolation and litigious behavior.8 Alternately, a patient with this disorder might not present for treatment until later in life after the loss of significant supporting factors, such as the death of parents or loss of steady employment. Examination of these older individuals is likely to reveal long-standing suspiciousness and distrust that previously was hidden by family members. For example, a 68-year-old woman might present saying that she can’t trust her daughter, but her recently deceased spouse would not let her discuss the topic outside of the home.
The etiology of paranoid personality disorder is unknown. Family studies suggest a possible a genetic connection to paranoia in schizophrenia.12 Others hypothesize that this dysfunction of personality might originate in early feelings of anxiety and low self-esteem, learned from a controlling, cruel, or sadistic parent; the patient then expects others to reject him (her) as the parent did.13,14 Such individuals might develop deep-seated distrust of others as a defense mechanism. Under stress, such as during a medical illness, patients could develop brief psychoses. Antipsychotic treatment might be useful in some cases of paranoid personality disorder, but should be limited.
Delusional disorder
Delusional disorder is a unique form of psychosis. Patients with delusional disorder might appear rational—as long as they are in independent roles—and their general functioning could go unnoticed. This could change when the delusions predominate their thoughts, or their delusional behavior is unacceptable in a structured environment. Such individuals often suffer from a highly specific delusion fixed on 1 topic. These delusions generally are the only psychotic feature. The most common theme is that of persecution. For example, a person firmly believes he is being followed by foreign agents or by a religious organization, which is blatantly untrue. Another common theme is infidelity.
Paranoia in delusional disorder is about something that is not actually occurring, but could.3 In other words, the delusion is not necessarily bizarre. The patient may have no evidence or could invent “evidence,” yet remain completely resistant to any logical argument against his belief system. In many situations, individuals with delusional disorder function normally in society, until the delusion becomes severe enough to prompt clinical attention.
Paranoia in schizophrenia
In patients with schizophrenia with paranoia, the typical symptoms of disorganization and disturbed affect are less prominent. The condition develops in young adulthood, but could start at any age. Its course typically is chronic and requires psychiatric treatment; the patient may require hospital care.
Although patients with delusional disorder and those with schizophrenia both have delusions, the delusions of the latter typically are bizarre and unlikely to be possible. For example, the patient might believe that her body has been replaced with the inner workings of an alien being or a robot. The paranoid delusions of persons with delusional disorder are much more mundane and could be plausible. Karl Jaspers, a clinician and researcher in the early 20th century, separated delusional disorder from paranoid schizophrenia by noting that the former could be “understandable, even if untrue” while the latter was “not within the realm of understandability.”5
A patient with schizophrenia with paranoid delusions usually experiences auditory hallucinations, such as voices threatening persecution or harm. When predominant, patients could be aroused by these fears and can be dangerous to others.2,4,5
Other presentations of paranoia
Paranoia can occur in affective disorders as well.13 Although the cause is only now being understood, clinicians have put forth theories for many years. A depressed person might suffer from excessive guilt and feel that he deserves to be persecuted, while a manic patient might think she is being persecuted for her greatness. In the past, response to electroconvulsive therapy was used to distinguish affective paranoia from other types.2
Paranoia in organic states
Substance use. Psychostimulants, which are known for their motor activity and arousal enhancing properties, as well as the potential for abuse and other negative consequences, could lead to acute paranoid states in susceptible individuals.15-17 In addition, tetrahydrocannabinol, the active chemical in Cannabis, can cause acute psychotic symptoms, such as paranoia,18,19 in a dose-dependent manner. A growing body of evidence suggests that a combination of Cannabis use with a genetic predisposition to psychosis may put some individuals at high risk of decompensation.19 Of growing concern is the evidence that synthetic cannabinoids, which are among the most commonly used new psychoactive substances, could be associated with psychosis, including paranoia.20
Dementia. Persons with dementia often are paranoid. In geriatric patients with dementia, a delusion of thievery is common. When a person has misplaced objects and can’t remember where, the “default” cognition is that someone has taken them. This confabulation may progress to a persistent paranoia and can be draining on caregivers.