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Time course of Delusions


As the later analysis will show, the duration of delusions varies widely from a few days to many years. Currently there is a diagnostic category called Acute and Transient Psychosis, which in essence describes a psychotic state that lasts three months or less. This of course applies to any delusions that are present. There are many questions that could be asked here. Are delusions of different length due to different types of underlying biological impairments? Are delusions that last a long time related to underlying brain damage? Could delusions that last a long time, simply be due to lack of treatment? Why does treatment leave some delusions unchanged?


Several studies that look at the issue of time in psychosis / delusions will be discussed, before moving on to discussing Acute and Transient Psychosis, before going to analysing the dataset.


A subset of patients from the McArthur Violence Risk Assessment study had their delusions assessed at various points in a 12-month period (Appelbaum 1999, 2004).

  • 29% were possibly or delusional, with 17% being delusional on one screening question.

  • 76% had more than one type of delusional content.

  • Those delusional at one follow up point, had a probability of 0.63 of being delusional at the next follow up point. Whereas the non-delusional had a probability of 0.08 of being delusional at the next follow up.

  • 15% were delusional at all follow up points, especially if they were single, older and schizophrenic

  • Conviction was highest in religious delusions and grandiosity, thought broadcasting, somatic, control, other, persecution and finally guilt (levels ranging from 33% to 60%).

  • Preoccupation with the delusion varied from 35% to 55%.

  • Pervasiveness ranged from 51% to 68% and reflects how much the delusional belief affected experiences.

  • For negative affect, values ranged from 25% to 69%.

  • In terms of reducing activity, values ranged from 18% to 32% and for performing actions because of the delusions, values ranged from 23% to 38%.

  • A similar variation in dimensional scores was found across the different diagnoses.


A subset of patients from the Chicago Follow-up Study were followed up at different time points over several years and compared to controls; 50% of those with schizophrenia and schizoaffective disorder were delusional at 2 years. The figures for (non)psychotic mood disorders were 40% and 23% respectively.  All figures dropped by the 4.5 year follow up period. Schizophrenics seem to more persistently delusional throughout, with schizoaffective patient’s showing little improvement after the second time point (Harrow 1995). There is also evidence to show that the age of onset of Delusional disorders is later than schizophrenia (Grover 2006).


A review of the course of delusional psychoses highlighted contradictory findings when it comes to identifying variables that could predict the long-term outcome of delusions. Some studies that found social factors e.g., relationships, employment, premorbid functioning, etc. are important and other studies that found clinical variables were relevant e.g., hallucinations, delusions, etc. There is a view that over the short-term premorbid personality is important, over the medium term domestic and psychopathological features over the long-term genetic loading may be the most important.  One study found the following (Schanda 1991).

  • Seven variables predicted remission - last 6 months before delusion onset, stress in interpersonal relationship, first manifestation, premorbid personality (e.g., obsessive compulsive), falsified memories, poor emotional relationship with father and good emotional resonance. These variables predicted 88% of those with remission or remission with relapse.

  • The variable ’delusions subsides or episodic’ predicted remission with 74% accuracy (chronic course lasting more than 1 year, illness duration, last 6 months before delusion onset: and stress in interpersonal relationship).

  • The outcome variable ‘transition to schizophrenic deficiency‘ predicted with 81% (formal thought disorder, poor emotional resonance and anxiety)

  • The outcome variable ‘hospitalisation ‘predicted remission with 84% accuracy using paraphrenic delusions.

  • The social adaptation variable predicted with 66% accuracy, using last 6 months before delusion onset and stress in interpersonal relationship


A long prospective study over 30 years found pathological mother child relationships in paranoid disorder, whilst pathological father child relationships was found in all groups. Neurotic traits were found in schizoaffectives and paranoid traits in 29% of the patient’s (females tended toward paranoid traits and males with schizoid traits (Opjordsmoen 1989a). An attempt was made to identify predictors using the above study and schizoid / avoidant traits predicted worse outcome at 30 years, with paranoid elements predicting better outcomes; more so for schizophrenia and schizoaffective disorders. Also, a restricted social network was linked to better outcomes (Opjordsmoen 1989b). Another longitudinal review of 56 patients from SansÆ in Denmark actually found depressive delusions were associated with full remission after an episode of illness (JÆrgensen 1986).


An obvious way that delusions can change with time is when treatment is given, be it medications or psychotherapy. For example, it has been found that cognitive behaviour therapy can alter the levels of conviction, preoccupation and anxiety associated with delusions. These components may have varied independently before treatment but altered together after treatment was started. (Chadwick 1994). A study of 92 hospitalised schizophrenics, found that delusion scores varied from baseline to review 4 years later, if patients were or were not consistently taking neuroleptics, this becoming non-significant when all patients were included. The scores between those taking and not taking neuroleptics were different, but with a p=0.04, this evidence was weak (Johnstone 1986).


Delusions are present in childhood mental illness, particularly schizophrenia (Paillere-Martinot 2000). A birth cohort of 3,617, born between 1981 – 1983, were followed for 21 years, with experiences being measured by the PDI, the child behaviour checklist (CBCL) and the youth self-report (YSR). The following was found. PDI scores at 21 were correlated to CBCL scores at 5 and 14 and YSR score at 14. Those scoring in the upper quartile of CBCL / YSR scores had the highest PDI scores / delusional experiences at 21. Delusional risk rose as psychopathology ratings increased from age 5 to 14. The highest delusional risk was for those with high CBCL scores at age 5 and YEARS scores at age14. Hallucinations at age 14 were associated with delusional experiences at age 21 (Scott 2009). The longer the duration of untreated psychosis, the longer it took for the delusions to settle (Gunduz Bruce 2007).


Looking at the other end of the age spectrum there are several factors associated with delusions. In terms of predictive factors for psychosis in Alzheimer’s Disease, it appeared the frontal lobe was involved e.g., verbal fluency. Also, factors present 1 year before delusions started were lower Mini Mental State Scores (a measure of cognitive function), grooved pegboard scores and Parkinsonism gait (Paulsen 2000). In elderly patients with paranoid psychoses there was a greater chance of delusions improving depending on the delusional content. The commonest delusions were persecution, control, reference / misinterpretation, depression and other (JÆrgensen 1985b). In 54 patients with probable AD, delusions were found in 38% at baseline and 65% at 2 years. The probability of a new delusion was 0.35, with the probability of a delusion persisting being 0.65. There was a 22% chance of delusions improving, 29% of a worsening and a 49% of stability in delusions (Eustace 2002).


Further investigations of how delusions change in schizophrenia found the odds ratio of delusions in the presence of hallucinations to be 3.5 (95% CI 2.0 – 5.8), such as delusions of control and reference. And in the presence of negative self-esteem to be 1.1 (95% CI 1.0 – 1.1). Delusions of control were negatively associated with conviction / activity disruption / negative self-esteem and fewer draws on a Jump To Conclusion trial. Delusions of reference were also predicted by negative self-esteem. Delusions of grandiosity were not predicted by any dimensions (Ben-Zeev 2012). A 20-year longitudinal study of 200 psychotic patients found that those who attended 5 of the 6 follow ups, schizophrenics tended to be more delusional and have more severe delusions. Though interestingly delusional activity at 15 and 20 years was less than that at the 2 years. 26% of schizophrenics were continuously delusional and 66% of the no psychotic group were non-delusional. The presence of delusions at one follow up point was correlated with the presence of delusions at following points, with this being stronger for schizophrenics (Harrow 2008).


Methodological issues may lie behind some of the variability in findings on the conversion to psychosis. Those people who report psychotic experiences may lie in the false positive group and this figure can be very large. To investigate this further the data from the NEMESIS-2 trial was used to investigate the correlation between self-reported psychotic experiences and confirmation by clinical interview - 16% reported psychotic experiences, but it was confirmed in 6%. This was also found in those who reported delusions, e.g., being spied on, being followed, being subjected to secret tests, victims of conspiracy, misidentifications, thoughts being read, thought interference, reference ideas from the TV or radio, being hypnotized, being controlled, or being influenced by non-living objects (Van Nierop 2012).


Conclusion – this brief review shows that delusions and their character changes with time. Though why this is and whether it has more than passing clinical relevance is not known.


Acute and Transient Psychosis (ATP) – In acute psychosis, these delusions can change over a much shorter timeline. These collections of conditions are characterised by acute onset (ICD-10) and less than 6 months duration (DSM-IV), though as a category the evidence base is limited (Singh 2004).  According to the ICD-10 version of classification of mental illness there are 6 types of this disorder (Udomartn 2012)


  • Acute polymorphic (rapidly changing) psychotic disorder without symptoms of schizophrenia

  • Acute polymorphic psychotic disorder with symptoms of schizophrenia

  • Acute schizophrenia like psychotic disorder

  • Other acute predominately delusional psychotic disorder

  • Other acute and transient psychotic disorders

  • Acute and transient psychotic disorders, unspecified


The key features are said to be onset that is acute, the presence of acute stress, quick remission, and the presence of typical syndromes.


A UK study investigated the nosological status of ATP. First presentations to a psychiatric unit identified 32 with ATP and followed them up for up to 3 years. Most were male, mostly under the age of 50, single and unemployed. After 3 years 70% of females but only 15% of males retained this diagnosis. They found roughly twice as many men had ATP as females, with an annual incidence of about 4 per 100000 (Singh 2004)


Prevalence of ATP varies from 4 to 10 per 100,100 depending on the country and there appears to be a female predominance. Though those with schizophrenic features are more often male. Stress in terms of life events may be found in about two thirds of cases, though other studies have not found this (Castagnini 2009).


Stability of this diagnosis has been looked at. 107 patients with ATP were followed up for two years. 90% were in the first 3 categories above. At the two year follow up point, the diagnosis was retained in 28%, but changed in 6%. 55 were eventually diagnosed with schizophrenia or schizoaffective disorder. Conversion to schizophrenia was more likely if patients were young, unmarried and had a longer time in hospital during their first admission (Aadamsoo 2011). Diagnostic stability in 16 patients with Acute polymorphic psychotic disorder without symptoms of schizophrenia, identified over 15 years in Japan were found to have nonaffective psychosis that did not conform to a schizophrenia and of these 6 were reclassified after about 12 years (Abe 2006). Conversion to schizophrenia may be predicted if there is a family history of schizophrenia, being young, male, having first rank symptoms and thought disorder (Malhotra 2019). Other studies have found transition to mood disorders can occur (Castagnini 2009).


In terms of differences from schizophrenia, 42 patients with ATP were recruited between 1993 – 1997 in Germany and compared to acute schizophrenics and healthy controls. During the index episode there was no difference in the prevalence of delusions, though delusional content rapidly changed in the acute group (p<0.0001). The acute group tended to have more hallucinations, anxiety and bipolar mood changes and were more likely to have an affective disorder but not schizophrenia (Marneros 2003). These same patients were compared to a group of patients with schizomania and again those with ATP were more likely to show rapidly changing delusional content, to have more mood swings, anxiety, to have an abrupt onset and to have suffered a life event in the 6 months before the index episode (Marneros 2002). A few years later these 42 patients were compared with an age and gender matched group of schizophrenics, with follow up occurring over the best part of 12 years. Those with ATP tended to retain function (Pillmann 2005). A series of 45 patients in India with ATP (classed as having gone into remission within 3 months) found that about 70% were female, 67% developed symptoms within 48 hours and about half recovered within a month. After 3 years, about 70% retained their ATP diagnosis and about a fifth were reclassified as having bipolar disorder (Sajith 2002).


There appears to be interesting cultural variations in the presentation of this group of disorders (Udomratin 2012). A Nigerian sample of 124 patients with ATP showed equal gender expression, most were under the age of 35, employed or in school, half were single and most had good levels of education. The authors felt that there was a greater prevalence of ATP in developing countries, with features that may be distinct from those with ATP in industrial countries. Stress was only found in a third and females tended to recover better than males. Delusions tended to persecutory and religious (Esan 2014). A meta-analysis of studies conducted in Asia found that the first 3 types of ATP (see above) tended to be the commonest types. There is evidence that it may be higher in-migrant populations. A lot of patients retained their diagnosis, with bipolar disorder being the commonest reclassified disorder, though in Japan schizophrenia was more likely. It has been said that in developing countries, ATP has a higher stability with a lower rate of relapse (Castagnini 2009).


There have been some interesting biological findings. The first-degree relatives of those with ATP may be up to three times to develop ATP. If these relatives developed ATP with schizophrenic features, they were more likely to develop schizophrenia, though replication is needed (Castagnini 2009, Das 1999). Looking at atypical psychosis (which some have said is related to ATP) have found some genes that may be related to ATP, that may also overlap with schizophrenic risk. Some inflammatory cytokines may be increased, e.g., IL-6, TNF-alpha and TGF beta (Malhotra 2019). From a sociological point a view, 94 patients with ATP were identified via a clinic in Germany, with 73 being followed up over the next 3 to 7 years. There were variable levels of functioning, ranging from 80% for personal care to 50% for working. Overall, 12% of patients showed poor social functioning (Jager 2003). Those with ATP may be more likely to have personality disorder of various types. A study of 51 patients with ATP found 32 had personality disorder, but 19 did not. Of those with personality disorder 15 were classed as unspecified (Jorgensen 1996).

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