Paranoid Schizophrenia vs Delusional Disorder

Analysis of the common psychopathological features in the various psychotic disorders suggest that symptoms can be clustered into five main categories: (Os & Kapur, 2009, p. 635)

1)      Psychosis, encompassing positive symptoms of delusions and hallucinations.

2)      Alterations in drive and volition, encompassing negative symptoms including lack of motivation, reduction in spontaneous speech, and social withdrawal.

3)      Alterations in neurocognition, encompassing cognitive symptoms including difficulties in memory, attention, and executive functioning.

4)      Affective dysregulation giving rise to depressive symptoms or 5) manic (bipolar) symptoms.

The term schizophrenia is typically applied to a syndrome that is characterized by a long duration, bizarre delusions, negative symptoms, and few affective symptoms (non-affective psychosis).  (Os & Kapur, 2009)  Formerly called dementia praecox, some of its associated features include inappropriate affect, anhedonia, dysphoric mood, lack of insight, depersonalization, and delrealization.  (Colman, 2009, p. 674)  Schizophrenia affects approximately 0.7% of the world’s population, with prevalence greater in men throughout adulthood, but equal by the end of the risk period.  Schizophrenia is highly heritable, with onset being rare before adolescence or after middle age (although men become ill earlier in life than women).  (MacDonald & Schulz, 2009, p. 495)  Schizophrenia subtypes include paranoid, disorganized, catatonic, undifferentiated, and residual types.  This article will focus on paranoid schizophrenia, which tends to be the least severe subtype of schizophrenia.

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“The essential feature of the Paranoid Type of Schizophrenia is the presence of prominent delusions or auditory hallucinations” where no disorganized speech, disorganized or catatonic behaviors, or flat or inappropriate affect is present.  (American Psychiatric Association, Diagnostic and statistical manual of mental disorders, 2000, p. 313)  Differential diagnosis is an exclusionary process since of all the other subtypes must be eliminated before diagnosing the paranoid subtype.  Paranoid schizophrenia sufferers typically have delusions that are persecutory and/or grandiose; they also typically have a recurrent theme.  Hallucinations are usually related to the same content theme as the delusions, and may include the associate features of anxiety, anger, aloofness, and/or argumentativeness.  Onset tends to be later in life when compared with other subtypes of schizophrenia, and the distinguishing characteristics are often more stable over time.  The prognosis is considerably better when compared with other schizophrenia subtypes, especially regarding occupational functioning and independent living.  (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000, p. 314)

“The essential feature of Delusional Disorder is the presence of one or more non-bizarre delusions that persist for at least 1 month.”  (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000, p. 323)  Bizarreness is mostly subjective since it is contingent on socio-cultural norms and expectations.  Bizarre delusions (as in schizophrenia) are “clearly implausible, not understandable, and not derived from ordinary life experiences.”  (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000, p. 324)  In contrast, non-bizarre delusions (as in delusional disorder) involve situations that could conceivably happen in real life… like being followed, poisoned, etc.  Subtypes of delusional disorder are categorized based on the content of the delusions or the theme thereof.  They include erotomanic, grandiose, jealous, persecutory, somatic, mixed, and unspecified types.  This essay will focus on persecutory delusions, although persecutory delusions often coexist with and are comorbid with other delusion types (particularly grandiose, in mixed presentation).

A determination of persecutory delusions is complicated by the fact that the incidence of persecutory thoughts is relatively common among the general population.  (Brown, 2008, p. 165)  “The criteria used to distinguish between these different categories of psychotic disorder are based on duration, dysfunction, associated substance use, bizarreness of delusions, and presence of depression or mania.”  (Os & Kapur, 2009, p. 635)  In delusional disorders, distortions of reality coexist with realms of rational, realistic thinking.  (Blaney & Millon, 2009, p. 361)  Delusional disorders are distinguished from schizophrenia by the absence of active phase symptoms of schizophrenia (e.g. prominent auditory or visual hallucinations, bizarre delusions, disorganized speech, grossly disorganized or catatonic behavior, and/or negative symptoms).  “Compared with schizophrenia, delusional disorder usually produces less impairment in occupational and social functioning.”  (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association, 2000, p. 327)

“The assessment of bizarreness is generally absent among lists of delusion dimensions, notwithstanding its key role in the distinction between DD and PS.”  (Blaney & Millon, 2009, p. 365)  To improve decision-making and reduce the chance of misdiagnosis, Brown (2008) suggests we ascertain, to the extent available, base rates of the specific persecutory beliefs (e.g. discrimination and harassment, mental illness stigma, criminal victimization, relationship infidelities, conspiracies, stalking, surveillance, poisoning, etc) in our area.  Secondly, he suggests we consider alternative hypotheses, especially in decisions that have a very low base rate.  While actively searching for disconfirming information, we should postpone decisions until further information is collected.  I agree with his suggestion that we should rely more on information, and less on intuition, when it comes to confirming or disconfirming persecutory beliefs.  (Brown, 2008, p. 172)

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American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author.

Blaney, P. H., & Millon, T. (2009). Oxford textbook of psychopathology (2nd ed.). New York, New York: Oxford University Press.

Brown, S. A. (2008). The reality of persecutory beliefs: Base rate information for clinicians. Ethical Human Psychology and Psychiatry, 10(3), 163-179. Retrieved from

Colman, A. M. (2009). Oxford dictionary of psychology (3rd ed.). Oxford, NY: Oxford University Press.

MacDonald, A. W., & Schulz, S. C. (2009, May ). What we know: Findings that every theory of schizophrenia should explain. Schizophrenia Bulletin, 35(3), 493-508. doi: 10.1093/schbul/sbp017

Os, J. V., & Kapur, S. (2009, Aug 22-Aug 28). Schizophrenia. The Lancet, 374(9690), 635-645. Retrieved from

2 thoughts on “Paranoid Schizophrenia vs Delusional Disorder

  1. Kieran Duffy

    This is a well written and informative article and helps me to understand the delusions of my paranoid brother.Thank you.

    1. Kent Brooks Post author

      Its just the perspective of one person, so take it with a grain of salt. By all accounts I am not technically liscenced to give any information and call it therapy, but I am more than willing to talk about your situation in more detail – a more private venue is probably preferable. Feel free to email me at brookskent (AT) hotmail (DOT) com


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