The inter-rater and test-retest reliabilities of prodromal symptoms in first-episode psychosis

On the proportion of patients who experience a prodrome prior to psychosis onset: A systematic review and meta-analysis

BACKGROUND

Preventing or delaying the onset of psychosis requires identification of those at risk for developing psychosis. For predictive purposes, the prodrome - a constellation of symptoms which may occur before the onset of psychosis - has been increasingly recognized as having utility. However, it is unclear what proportion of patients experience a prodrome or how this varies based on the multiple definitions used.

METHODS

We conducted a systematic review and meta-analysis of studies of patients with psychosis with the objective of determining the proportion of patients who experienced a prodrome prior to psychosis onset. Inclusion criteria included a consistent prodrome definition and reporting the proportion of patients who experienced a prodrome. We excluded studies of only patients with a prodrome or solely substance-induced psychosis, qualitative studies without prevalence data, conference abstracts, and case reports/case series. We searched Ovid MEDLINE, Embase (Ovid), APA PsycInfo (Ovid), Web of Science Core Collection (Clarivate), Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, APA PsycBooks (Ovid), ProQuest Dissertation & Thesis, on March 3, 2021. Studies were assessed for quality using the Critical Appraisal Checklist for Prevalence Studies. Narrative synthesis and proportion meta-analysis were used to estimate prodrome prevalence. I2 and predictive interval were used to assess heterogeneity. Subgroup analyses were used to probe sources of heterogeneity. (PROSPERO ID: CRD42021239797).

RESULTS

Seventy-one articles were included, representing 13,774 patients. Studies varied significantly in terms of methodology and prodrome definition used. The random effects proportion meta-analysis estimate for prodrome prevalence was 78.3% (95% CI = 72.8-83.2); heterogeneity was high (I2 97.98% [95% CI = 97.71-98.22]); and the prediction interval was wide (95% PI = 0.411-0.936). There were no meaningful differences in prevalence between grouped prodrome definitions, and subgroup analyses failed to reveal a consistent source of heterogeneity.

CONCLUSIONS

This is the first meta-analysis on the prevalence of a prodrome prior to the onset of first episode psychosis. The majority of patients (78.3%) were found to have experienced a prodrome prior to psychosis onset. However, findings are highly heterogenous across study and no definitive source of heterogeneity was found despite extensive subgroup analyses. As most studies were retrospective in nature, recall bias likely affects these results. While the large majority of patients with psychosis experience a prodrome in some form, it is unclear if the remainder of patients experience no prodrome, or if ascertainment methods employed in the studies were not sensitive to their experiences. Given widespread investment in indicated prevention of psychosis through prospective identification and intervention during the prodrome, a resolution of this question as well as a consensus definition of the prodrome is much needed in order to effectively direct and organize services, and may be accomplished through novel, densely sampled and phenotyped prospective cohort studies that aim for representative sampling across multiple settings.

Duration of untreated psychosis is associated with temporal and occipitotemporal gray matter volume decrease in treatment naïve schizophrenia

Background

Long duration of untreated psychosis (DUP) is associated with poor treatment outcome. Whether or not DUP is related to brain gray matter volume abnormalities in antipsychotic medication treatment naïve schizophrenia remains unclear at this time.

Methods

Patients with treatment-naïve schizophrenia and healthy controls went through brain scan using high resolution Magnetic Resonance Imaging. DUP was evaluated using the Nottingham Onset Schedule (NOS), and dichotomized as short DUP (≤ 26 weeks) or long DUP (>26 weeks). Voxel-based methods were used for volumetric measure in the brain.

Results

Fifty-seven patients (27 short DUP and 30 long DUP) and 30 healthy controls were included in the analysis. There were significant gray matter volumetric differences among the 3 groups in bilateral parahippocampus gyri, right superior temporal gyrus, left fusiform gyrus, left middle temporal gyrus, and right superior frontal gyrus (p's<0.01). Compared with healthy controls, the long DUP group had significantly smaller volume in all these regions (p's <0.05). Compared with the short-DUP group, the long-DUP group had significantly smaller volume in right superior temporal gyrus, left fusiform gyrus, and left middle temporal gyrus (p's<0.01).

Conclusion

Our findings suggest that DUP is associated with temporal and occipitotemporal gray matter volume decrease in treatment naïve schizophrenia. The brain structural changes in untreated psychosis might contribute to poor treatment response and long-term prognosis in this patient population.

Kraepelin and psychotic prodromal conditions

When Emil Kraepelin combined the formerly distinct entities of dementia paranoides, catatonia and hebephrenia to form the concept of 'dementia praecox' in 1896, he was well aware that this new disease entity--first coined 'schizophrenia' by Eugen Bleuler in 1908--does not generally only start off with the first psychotic manifestation. Even in his original observations, the characteristic psychotic phenomena developed via transition sequences from rather uncharacteristic prodromal disturbances. Meanwhile an initial prodromal condition was shown for about 75% of first-episode psychosis patients, lasting 5 years on average, possessing pathological significance and leading to psychosocial disruptions. Whereas most symptoms of the initial prodromal condition appear to be rather unspecific and hard to distinguish from other psychiatric conditions especially depressive ones, some syndromes seem to enable an early detection and thus an indicated prevention. These are constituted by attenuated and/or transient psychotic symptoms on the one hand and certain cognitive-perceptive basic symptoms on the other. Whereas the former are thought to delineate an advanced prodromal state, the latter can occur early in course and even at the beginning of the transition sequence to first-rank symptoms. This review will outline the current state of the art of a phase specific early detection and intervention based on these syndromes.

Determining the chronology and components of psychosis onset: The Nottingham Onset Schedule (NOS)

The Nottingham Onset Schedule (NOS) is a short, guided interview and rating schedule to measure onset in psychosis. Onset is defined as the time between the first reported/observed change in mental state/behaviour to the development of psychotic symptoms. Onset is conceptualised as comprising of (i) a prodrome of two parts: a period of 'unease' followed by 'non-diagnostic' symptoms; (ii) appearance of psychotic symptoms; and (iii) a build-up of diagnostic symptoms leading to a definite diagnosis. Twenty consecutive cases of first-episode psychosis were administered the NOS schedule to determine its psychometric properties including inter-rater and test-retest reliability. Its clinical and research potential as a reliable measure of duration of untreated psychosis (DUP) was assessed in a cohort of 99 cases of first-episode psychosis (56 schizophrenia, 43 affective psychoses). NOS identified all prodromal symptoms previously reported in other studies. There was high degree of inter-rater and test-retest reliability for all components of NOS. Duration of untreated psychosis was significantly longer (p<0.05) in schizophrenia (mean 179 days, S.D. 344; median 52 days) than in affective psychosis (mean 15 days, S.D. 116; median 12 days) but there were no gender differences between lengths of prodrome or treatment delays. The NOS provides a standardised and reliable way of recording early changes in psychosis and identifying relatively precise time points for measuring several durations in emerging psychosis. The scale is easy to use and is not time-consuming or labour intensive. Onset, as measured by NOS, is significantly longer in schizophrenic disorders than in affective psychosis. A small proportion of schizophrenia cases have very long DUP. Some cases with schizophrenia receive anti-psychotics in the prodromal phase, prior to the emergence of frank psychotic symptoms.

A esquizofrenia ao longo da infância

As pesquisas sobre os grupos “de alto risco” (filhos de pais esquizofrênicos), assim como os estudos prospectivos na população geral, mostram que os futuros esquizofrênicos apresentam, comparativamente aos sujeitos-controle, atrasos do desenvolvimento psicomotor, déficits cognitivos e algumas particularidades comportamentais. Tais dados parecem confirmar a idéia segundo a qual a esquizofrenia corresponderia a um distúrbio neurodesenvolvimental cuja expressão varia ao longo da vida. As especificidades clínicas e evolutivas dos raros casos de esquizofrenia iniciando-se na infância levam alguns autores a pensar que se trataria de uma entidade específica e cujo pertencimento ao “espectro autista” necessita ainda ser estudado.

Risk factors for transition to first episode psychosis among individuals with 'at-risk mental states'

Recently developed criteria have been successful at identifying individuals at imminent risk of developing a psychotic disorder, but these criteria lead to 50-60% false positives. This study investigated whether measures of family history, peri-natal complications, premorbid social functioning, premorbid personality, recent life events and current symptoms would be able to improve predictions of psychosis in a group of young, help-seeking individuals who had been identified as being at risk. Individuals (N=74) were followed up at least 1 year after initial assessment. Half the sample went on to develop a psychotic disorder. The most reliable scale-based predictor was the degree of presence of schizotypal personality characteristics. However, individual items assessing odd beliefs/magical thinking, marked impairment in role functioning, blunted or inappropriate affect, anhedonia/asociality and auditory hallucinations were also highly predictive of transition, yielding good sensitivity (84%) and specificity (86%). These predictors are consistent with a picture of poor premorbid functioning that further declines in the period up to transition.

Autochthonous experience, heightened awareness, and perception distortion in patients with schizophrenia: a symptomatological study

Early symptoms of schizophrenia' (ESS) proposed by Nakayasu, are present during schizophrenic prodromal periods. Some of these symptoms can continue after the florid manifestation of the disease and the patients often experience them with ego-alien feelings. Autochthonous experience, heightened awareness, and perception distortion (AHP) were selected from the list of ESS. The aim of this study was to confirm both prevalence and specificity of AHP in patients with schizophrenia as well as the relevance of the presence of AHP to symptomatology of schizophrenia. A structured interview was conducted to identify the presence of AHP in three groups of subjects; a schizophrenia group (Sc) with 37 patients, an affective disorder group (AD) with 27 patients, and a control group (NC) with 39 people. The prevalence of AHP was compared among the groups. Within the Sc, the relevance of AHP to Brief Psychiatric Rating Scale (BPRS) was assessed. AHP were present significantly more frequently in the Sc. The total scores for BPRS in the schizophrenic patients with AHP were significantly higher than in the patients without AHP. There was close correlation between AHP and BPRS items, with the degree of relevance depending on the form or perceptual domain. In conclusion, AHP were characteristic of patients with frank schizophrenia. To judge whether AHP were adequately specific to frank schizophrenia, further research of larger subjects is needed. Understanding the characteristics of AHP in patients with frank schizophrenia is important in the symptomatological evaluation of schizophrenia.

Characterizing and dating the onset of symptoms in psychotic illness: the Symptom Onset in Schizophrenia (SOS) inventory

Prodromal symptoms, including disturbances of perceptions, beliefs, cognition, affect, and behavior, are often the first symptoms of schizophrenia. Little is understood about the initial, prodromal stage of schizophrenia, despite the compelling research and clinical need. The development and psychometric properties of a new, time-efficient instrument to characterize and date the initial symptoms of a psychotic illnesses, the Symptom Onset in Schizophrenia (SOS) scale, is described in this paper. The SOS rates the presence and dates the onset of 16 general prodromal, positive, negative, and disorganizational symptoms, as well as a clinician, family, and patient global rating of onset of illness. Inter-rater reliability for the presence of each symptom in 35 patients with schizophrenia, schizoaffective, or schizophreniform disorder was good to excellent, with kappa coefficient >0.7 for 12 items, and >0. 5 for all items. Agreement on symptom duration was good to excellent for individual items (ICC=0.7-1.0) and for global rating of duration of illness (ICC=0.97). Our data indicate that the SOS is a reliable, valid, time-efficient tool useful to retrospectively assess the onset of schizophrenia and related psychotic disorders. Further study is underway to evaluate other psychometric properties of the SOS, including test-retest reliability and predictive validity.

The initial prodrome in psychosis: descriptive and qualitative aspects

OBJECTIVE

This study aimed to describe in detail, using a retrospective approach, the prodromal symptoms in first-episode psychosis patients. This initial prodrome, the period of disturbance preceding a first psychotic episode, is potentially important for early intervention, identification of biological markers, and understanding the process of becoming psychotic.

METHOD

A consecutive series of 21 first-episode patients was recruited from the Early Psychosis Prevention and Intervention Centre, a specialised service for young people aged between 16 and 30 with first-episode psychosis. Subjects were interviewed in the recovery phase after the acute episode, about the period leading up to the psychosis, using a combination of unstructured and semi-structured techniques.

RESULTS

A wide variability of phenomena and sequence patterns was found, with symptoms being a mixture of attenuated psychotic symptoms, neurotic and mood-related symptoms, and behavioural changes. Symptoms were often disabling and some, such as suicidal thoughts, potentially life-threatening.

CONCLUSIONS

The findings highlight the loss of information that has resulted from disregarding early phenomenological studies of the psychotic prodrome and instead focussing on behavioural features. The ground work has been laid for the development of better methodologies for assessing and measuring first psychotic prodromes with increased emphasis on experiential phenomena. This has the potential to lead to the early recognition and more accurate prediction of subsequent psychosis, as well as a deeper understanding of the neurobiology of the onset of psychotic disorder.