Reasons for the diagnostic discordance between clinicians and researchers in schizophrenia in the Northern Finland 1966 Birth Cohort

Background: The diagnosis of schizophrenia by clinicians is not always accurate in terms of operational diagnostic criteria despite the fact that these diagnoses form the basis of case registers and routine statistics. This poses a challenge to psychiatric research. We studied the reasons for diagnostic discordance between clinicians and researchers. Methods: The Northern Finland 1966 Birth Cohort (n = 11,017) was followed from mid-gestation to the end of the 31st year. Psychiatric outcome was ascertained through linkage to the national hospital discharge register containing clinical diagnoses made by the attending physician. The hospital notes of all subjects admitted to hospital during the period 1982–1997 due to psychiatric disorder were reviewed and 475 research, operational DSM-III-R diagnoses were formulated. Results: Ninety-six cases met operational criteria for schizophrenia. Fifty-five (57 %) had concordant diagnoses: both the clinical and research diagnoses were schizophrenia. Forty-one (43 %) had discordant diagnoses: the clinical diagnosis was other than schizophrenia (mainly schizophreniform or other psychosis). Discordant cases were more likely to be older at onset, experience a shorter treatment duration, fewer treatment episodes, and to have a comorbid diagnosis mental retardation. Conclusions: Clinicians do not make the diagnosis of schizophrenia as often as the application of operational criteria would suggest they should. The discordance between clinical diagnosis and the research, operational diagnosis is especially likely in cases having late onset and few contacts to psychiatric hospital. Accepted: 12 December 2002 Correspondence to Kristiina Moilanen, MD     

Young people at risk for psychosis: case finding and sample characteristics of the Oulu Brain and Mind Study

Aim: Set within the general population‐based Northern Finland Birth Cohort 1986, the Oulu Brain and Mind Study aims to explore the causes and pathogenesis of psychotic illness by following young people at risk for psychosis due to having a first‐degree relative with psychotic illness or due to having experienced psychotic‐like symptoms themselves. We report the study methods and explore the relationship between these definitions of high risk for psychosis and operational criteria for a prodromal psychosis syndrome based on interview. Methods: Prospectively collected data from earlier follow‐ups of this cohort were combined with health register data to categorize subjects as those with familial risk (n = 272), symptomatic risk (n = 117), psychosis (n = 78), attention deficit hyperactivity disorder (ADHD) (n = 103) and a sample of controls (n = 193) drawn randomly from the remaining cohort. The Structured Interview for Prodromal Syndromes (SIPS) was applied to all, 295 participants together with questionnaires measuring psychosis vulnerability and schizotypal traits. Results: There were 29 (10%) current prodromal cases. Criteria for the current prodromal syndrome were fulfilled by 12% of the familial risk group and 19% of the symptomatic risk group, compared with 5% of the ADHD group and 4% of controls. Conclusion: We successfully detected young people with a prodromal psychosis syndrome although relatively few subjects deemed to be at high risk met the full operational criteria according to the SIPS interview. Combining methods from familial, clinical and psychometric high‐risk approaches provides a tractable method for studying risk of psychosis in the general population.     

Cannabis and schizophrenia: a longitudinal study of cases treated in Stockholm County

By means of the Stockholm County inpatient care register we identified all cases treated with a diagnosis of cannabis dependence and psychosis, not necessarily at the same occasion, during 1971–1983. By scrutinizing medical records, we evaluated the diagnosis according to DSM-III-R and we assessed the history of substance abuse as well as the psychiatric history and clinical course. We identified 229 cases during the follow-up; 112 of these cases (49%) fulfilled the DSM-III-R criteria for schizophrenia. The majority of the schizophrenics had prominent positive symptoms and a sudden onset of disease, and 69% of the cases had a record of heavy cannabis abuse at least 1 year before onset of psychotic symptoms. The high number of verified DSM-III-R cases of schizophrenia in this cohort and the temporal relation between cannabis abuse and schizophrenia further support the hypothesis that cannabis abuse may be a risk factor for schizophrenia. We confirmed previous observations that cannabis-associated schizophrenia often has a sudden onset and prominent positive symptoms.     

Recovery from schizophrenic psychoses within the northern Finland 1966 Birth Cohort

BACKGROUND: Because of widely disparate findings from follow-up studies, the likelihood of recovery from schizophrenia remains controversial. We report the extent of recovery from schizophrenia in a population-based cohort. METHOD: Subjects with psychotic disorders were recruited from the Northern Finland 1966 Birth Cohort. Of the 91 subjects who agreed to participate, 59 were diagnosed with schizophrenia and 12 were diagnosed with schizophrenia spectrum disorders (schizophreniform psychosis, schizoaffective or delusional disorder) by DSM-III-R criteria. Diagnoses were established by interviewing the subjects, checking the Finnish Hospital Discharge Register, and reviewing their medical records. To assess recovery, we used the Clinical Global Impressions; the Positive and Negative Syndrome Scale; the Social and Occupational Functioning Assessment Scale; and information about psychiatric hospitalizations, use of antipsychotic medication, and occupational status. RESULTS: Only 1 subject (1.7%) with DSM-III-R schizophrenia and 3 subjects (25%) with schizophrenia spectrum disorders fully recovered; 1 schizophrenia subject (1.7%) and 2 schizophrenia spectrum subjects (16.7%) experienced partial recovery. CONCLUSION: The data indicate that, at least until age 35, complete recovery from schizophrenia is rare, and the prognosis for the disorder is far more serious than suggested by some follow-up studies.     

Patterns of psychiatric hospitalizations in schizophrenic psychoses within the Northern Finland 1966 Birth Cohort

We report patterns of hospitalization in schizophrenic psychoses by age 34 in a longitudinal population-based cohort. We test the predictive ability of various demographic and illness-related variables on patterns of hospitalization, with a special focus on the length of the first psychiatric hospitalization. All living subjects of the Northern Finland 1966 Birth Cohort with DSM-III-R schizophrenia (n=88) and other schizophrenia spectrum cases (n=27) by the year 1997 in the Finnish Hospital Discharge Register were followed for an average of 10.5 years. Measures of psychiatric hospitalization included time to re-hospitalization (as continuous and as re-hospitalization within 2 years) and the number of hospital episodes. Length of the first hospitalization, other illness-related and various socio-demographic predictors were used to predict hospitalization patterns. After adjusting for gender, age at first admission and number of hospital days a short (1–14 days) first hospitalization (reference >30 days; adjusted odds ratio 6.39; 95% CI 2.00–20.41) and familial risk of psychosis (OR 3.36; 1.09–10.39) predicted re-hospitalization within 2 years. A short first hospitalization also predicted frequent psychiatric admissions defined as the first three admissions within 3 years (OR 13.77; 3.92–48.36). A short first hospitalization was linked to increased risk of re-hospitalizations. Although short hospitalization is recommended by several guidelines, there may be a group of patients with schizophrenic psychoses in which too short a hospitalization may lead to inadequate treatment response.     

Early developmental milestones in adult schizophrenia and other psychoses. A 31-year follow-up of the Northern Finland 1966 Birth Cohort

Delayed childhood development may precede adult psychoses. We tested this hypothesis in a large, general population birth cohort (n=12058) followed to age 31 years. The ages at which individuals learned to stand, walk, speak, and became potty-trained (bowel control) and dry (bladder control), were recorded at a 1-year examination. Psychiatric outcome was ascertained through linkage to a national hospital discharge register. Cumulative incidence of DSM-III-R schizophrenia, other psychoses and non-psychotic disorders were stratified according to the timing of milestones and compared within the cohort using internal standardization. 100 cases of DSM-III-R schizophrenia, 55 other psychoses, and 315 non-psychotic disorders were identified. The ages at learning to stand, walk and become potty-trained were each related to subsequent incidence of schizophrenia and other psychoses. Compared with the whole cohort, earlier milestones reduced, and later milestones increased, the risk in a linear manner. These developmental effects were not seen for non-psychotic outcomes. The findings support hypotheses regarding psychosis as having a developmental dimension with precursors apparent in early life.     

Prevalence and diagnosis of schizophrenia based on register, case record and interview data in an isolated Finnish birth cohort born 1940–1969

Introduction Schizophrenia occurs worldwide but the prevalence varies markedly. In Finland, schizophrenia is most prevalent in the northeastern region. Our aims were to reassess the register-, case record- and interview-based lifetime prevalence in a genetically homogeneous birth cohort from an isolate population with earlier reported high prevalence of schizophrenia and a chromosome linkage to chromosome 1q. Methods We identified all patients with a diagnosis of schizophrenia [International Classification of Diseases (ICD)-8, ICD-9 or ICD-10 codes], born 1940–1969 in the isolate (n=282) and alive (n=237) in 1998 using the Hospital Discharge, Disability Pension and Free Medicine Registers. The corresponding birth cohort of 14,817 persons and 12,368 alive in 1998 was identified from the National Population Register. We validated 69% of the register diagnosis by making DSM-IV consensus diagnoses, and interviewed 131 (55%) of the 237 patients with SCID-I and SCID-II. Results The register-based lifetime prevalence was 1.5% for schizophrenia and 1.9% for schizophrenia spectrum psychotic disorders: in birth cohorts born 1945 to 1959, the latter prevalence was especially high (2.4%). Of those with a register diagnosis of schizophrenia spectrum psychotic disorder, 69% or 63% also received a record-based consensus diagnosis or SCID interview diagnosis of schizophrenia, and the prevalence was 0.9–1.3 and 0.7–1.2%, respectively, when we reassessed most of the register-based cases. The cumulative incidence of schizophrenia spectrum psychotic disorders in the total birth cohort was 1.9%. Conclusion In this isolate, the register, DSM-IV consensus and SCID interview-based lifetime prevalence of schizophrenia was internationally high. For genetic research work, the register diagnosis should be reassessed using either structured interview or the best estimate consensus diagnosis.     

Hippocampus and amygdala volumes in schizophrenia and other psychoses in the Northern Finland 1966 birth cohort

Structural brain differences have been reported in many studies with schizophrenia, but few have involved a general population birth cohort. We investigated differences in volume, shape and laterality of hippocampus and amygdala in patients with schizophrenia, all psychoses and comparison subjects within a large general birth cohort sample, and explored effects of family history of psychosis, perinatal risk and age-at-onset of illness. All subjects with psychosis from the Northern Finland 1966 birth cohort were invited to a survey including MRI scan of the brain, conducted in 1999-2001. Comparison subjects not known to have psychosis were randomly selected from the same cohort. Volumes of hippocampus and amygdala were measured in 56 subjects with DSM-III-R schizophrenia, 26 patients with other psychoses and 104 comparison subjects. Small hippocampal volume reductions in schizophrenia (2%) and all psychoses (3%) were not significant when adjusted for total brain volume. The shape of hippocampus in schizophrenia did not differ significantly from comparison subjects. Right hippocampus and amygdala were significantly larger than the left in all groups. Mean amygdala volume in schizophrenia or all psychoses did not differ from comparison subjects. Patients with family history of psychosis had larger hippocampus than patients without. Neither perinatal risk nor age-at-onset of illness had any effect on hippocampal or amygdala volumes. Small hippocampal volume reduction in schizophrenia and all psychoses was not disproportionate to reduced whole brain volume in this population-based sample. Perinatal events that have been suggested as of etiological importance in structural pathology of psychosis had no effect.     

Can excellent school performance be a precursor of schizophrenia? A 28-year follow-up in the Northern Finland 1966 birth cohort

OBJECTIVE: Poor scholastic performance is known to pre-date adult schizophrenia. We studied the 1966 North Finland general population birth cohort (n = 11017) in order to determine whether excellent school performance was a risk or protective factor. METHOD: Data on school marks at the age of 16 years were linked to data on psychiatric morbidity. In total, 89 subjects (58 boys) developed DSM-III-R schizophrenia between the ages of 16 and 28 years. RESULTS: Six (11%) of the pre-schizophrenic boys (6/54) had excellent mean school marks, compared to only 3% (166/5245) of the comparison group (OR 3.8; 95% CI 1.6-9.3, adjusted for parental social class, place of residence and birth order). CONCLUSION: These results may be a chance phenomenon and require replication. However, adult schizophrenia may be linked to excellent school performance. This result may be relevant both to the preservation of schizophrenia in the population, and to mechanisms of developing schizophrenia.     

Association between age at onset and clinical features of schizophrenia: The Northern Finland 1966 birth cohort study

PURPOSE: To study the association between age at onset and the clinical picture of schizophrenia in an unselected young birth cohort. SUBJECTS AND METHODS: The study sample consists of 98 (64 males and 34 females) individuals with DSM-III-R schizophrenia collected from the Northern Finland 1966 birth cohort. Firstly, subjects were divided into very early- and young-onset subgroups by using the median age at onset (22 years in males and 20 in females), as a cut-off point. Secondly, we used age at onset as a continuous variable. Clinical features of schizophrenia were assessed using the Operational Criteria Checklist for Psychotic Illnesses (OCCPI). RESULTS: Inappropriate affect, positive thought disorder and deterioration from premorbid level of function associate with very early-onset schizophrenia, while slowed activity and dysphoria relate to young-onset. These symptoms correlate significantly with the age at onset. DISCUSSION: Differences in the clinical picture associating to the age at onset of schizophrenia are seen early. CONCLUSION: These findings indicate that certain symptoms of schizophrenia are dependent on the age at onset, and schizophrenia occurring initially in early life has some typical features. Using the age at onset as a continuous variable is independent of arbitrary cut-off points and produces more explicable results.     

The prevalence of prodromal features of schizophrenia in adolescence: a preliminary survey

In most cases of schizophrenia the onset of frank psychosis is preceded by a period of prodromal features. This period has been relatively neglected by researchers and is potentially important in promoting early intervention. The prevalence of DSM-III-R schizophrenia prodrome symptoms was assessed as part (n= 657) of a large (n= 2525) questionnaire-based survey of high school students. Individual symptoms were highly prevalent and the prevalence of DSM-III-R prodromes ranged from 10–15% to 50%. Despite methodological weaknesses, the data suggest that DSM-III-R prodromal features are extremely prevalent among older adolescents and unlikely to be specific for subsequent schizophrenia. Clinically these features cannot be regarded as sufficient evidence of early schizophrenia and more accurate predictors of incipient schizophrenia need to be defined.     

Patterns of psychiatric hospitalizations in schizophrenic psychoses within the Northern Finland 1966 Birth Cohort

We report patterns of hospitalization in schizophrenic psychoses by age 34 in a longitudinal population-based cohort. We test the predictive ability of various demographic and illness-related variables on patterns of hospitalization, with a special focus on the length of the first psychiatric hospitalization. All living subjects of the Northern Finland 1966 Birth Cohort with DSM-III-R schizophrenia (n=88) and other schizophrenia spectrum cases (n=27) by the year 1997 in the Finnish Hospital Discharge Register were followed for an average of 10.5 years. Measures of psychiatric hospitalization included time to re-hospitalization (as continuous and as re-hospitalization within 2 years) and the number of hospital episodes. Length of the first hospitalization, other illness-related and various socio-demographic predictors were used to predict hospitalization patterns. After adjusting for gender, age at first admission and number of hospital days a short (1-14 days) first hospitalization (reference >30 days; adjusted odds ratio 6.39; 95% CI 2.00-20.41) and familial risk of psychosis (OR 3.36; 1.09-10.39) predicted re-hospitalization within 2 years. A short first hospitalization also predicted frequent psychiatric admissions defined as the first three admissions within 3 years (OR 13.77; 3.92-48.36). A short first hospitalization was linked to increased risk of re-hospitalizations. Although short hospitalization is recommended by several guidelines, there may be a group of patients with schizophrenic psychoses in which too short a hospitalization may lead to inadequate treatment response.     

Psychogenic (reactive) and hysterical psychoses: a cross-system reliability study

The aim of this study was to investigate the concepts of reactive and hysterical psychoses and how they are classified in standardized diagnostic Systems. To this end we identified all of the patients who had been admitted to a psychiatric in-patient unit and diagnosed as suffering from psychogenic psychosis, reactive psychosis, hysterical psychosis or hysteria, using ICD-9 criteria. The case notes of these patients were then re-examined and diagnoses reached using DSM-III-R, DSM-IV and ICD-10 criteria and the Present State Examination (PSE)/catego computer program. The objective of this study was to evaluate the agreement between the diagnoses of reactive and hysterical psychosis obtained using ICD-9 criteria with those obtained using the DSM-III-R, DSM-IV, ICD-10 and PSE diagnostic Systems. A total of 67 case notes were identified in which the above diagnoses had been made: 27 cases with ICD-9 ‘hysteria’ and 26 cases with ‘other reactive and not otherwise specified psychoses’. Using the DSM-III-R criteria, 27 cases were diagnosed as psychotic disorder NOS, 12 as brief reactive psychosis and 11 as bipolar disorder. Using the DSM-IV criteria, 21 cases were diagnosed as psychotic disorder NOS, 11 as mood disorder, 7 as brief disorder without stressor, and 12 as brief disorder with stressor. Using the ICD-10 criteria, 18 cases were diagnosed as unspecified non-organic psychosis, 12 as mood disorder, 10 as acute and transient psychotic disorder without stressor and 13 as acute and transient psychotic disorder with stressor. Using the PSE/catego program, the most common diagnoses were class ‘S’ schizophrenia (17), class ‘P?’ uncertain psychosis (16) and class ‘M+’ mixed and manic affective disorder (11). Using the kappa coefficient a very low level of agreement was found between ICD-9 ‘hysteria’ and ‘other reactive and non-specified psychoses’ and the corresponding categories of DSM-III-R and the PSE/catego program. We concluded that, although DSM-III-R provides operational criteria for brief reactive psychosis, and DSM-IV and ICD-10 provide such criteria for brief or acute psychotic disorder, these bear little relationship to the original concept of the disorder. The PSE/catego program provides a very systematic approach to symptomatology, but the diagnostic classes have little clinical usefulness.     

The influence of the patients’ ethnicity,socio-demographic conditions and strain on psychiatric diagnoses given at an outpatient clinic

Although psychiatric diagnoses are influenced by cultural and social conditions, with large global variations, the ICD and DSM systems are applied worldwide. The aims of this study were to describe the distribution of different ethnic patient groups in psychiatric outpatient services and the influence of ethnicity, demographic conditions and social strain on psychiatric diagnoses. An entire year's cohort of psychiatric outpatients (n=839) in an outpatient register was divided into nine groups, according to country of birth. The proportion of each group in the outpatient population was compared with its corresponding proportion in the catchment area. In order to examine the relationship between socio-demographic variables and strain on the one hand, and DSM-III-R diagnoses on the other, stepwise logistic regression analyses were carried out. Swedes were the only group under-represented as outpatients (P<0.001). Africans ran a higher risk (OR=5.55, 95% CI=2.56–12.04) than other ethnic groups of receiving a diagnosis of psychotic disorder – except schizophrenia – and Greek patients were more likely to receive a diagnosis of somatoform disorder (OR=8.81, 95% CI=4.41–17.59). Swedes were twice as likely to receive a diagnosis of personality disorder (OR=2.16, 95% CI=1.55–3.15). Schizophrenia was related to male gender (OR=1.75, 95% CI=1.04–2.94) and affective disorders to age >40 years (OR=1.71, 95% CI=1.22–2.40). Ethnicity has a strong impact on how diagnoses are given in cross-cultural settings. We could not confirm earlier findings of under-representation of ethnic minorities in outpatient services.     

A 4-fold risk of metabolic syndrome in patients with schizophrenia: the Northern Finland 1966 Birth Cohort study

OBJECTIVE: Schizophrenia is associated with a shortened life expectancy and increased somatic comorbidity with, e.g., cardiovascular disorders. One major risk factor for these disorders is the metabolic syndrome, which has been reported to have a higher frequency in schizophrenic patients. Our objective was to study the prevalence of metabolic syndrome in a population-based birth cohort. METHOD: The study sample consisted of 5613 members of the Northern Finland 1966 Birth Cohort who participated in the field study from 1997 to 1998. Subjects were divided into 4 diagnostic categories (DSM-III-R): (1) schizophrenia (N = 31), (2) other functional psychoses (N = 22), (3) nonpsychotic disorders (N = 105), and (4) no psychiatric hospital treatment (N = 5455, comparison group). Subjects were assessed for the presence of metabolic syndrome according to the criteria of the National Cholesterol Education Program. RESULTS: The prevalence of metabolic syndrome was higher in subjects with schizophrenia compared with the comparison group (19% vs. 6%, p = .010). The prevalence of metabolic syndrome in subjects with other psychoses was 5%. After controlling for sex, the results of logistic regression analysis showed that the risk of metabolic syndrome in schizophrenia was 3.7 (95% CI = 1.5 to 9.0). CONCLUSIONS: The high prevalence of metabolic syndrome in schizophrenia even at such a relatively young age underscores the need to select antipsychotic medications with no or little capability to induce metabolic side effects. Also, developing comprehensive efforts directed at controlling weight and diet and improving physical activity are needed.     

Admission pattern and diagnostic stability among unipolar and bipolar manic-depressive patients

The instability of the diagnoses in a psychiatric register causes practical problems when groups of probands with specific diagnoses are selected for further studies. A cohort of 3,062 first admissions with at least one manic-depressive admission was followed for 5-7 years. 623 had at least one admission for mania and were considered bipolar. The percentage of patients who changed their diagnoses was highest at first readmission; at each later readmission about 10% of the bipolars and 25% of the unipolars changed from manic-depressive psychosis and a similar number changed from other diagnoses to manic-depressive psychosis. Compared with the diagnostic distribution of all register cases, reactive psychoses were more frequent than expected as former diagnoses and schizophrenia as later diagnosis. Neuroses and character deviations were frequent alternative diagnoses among unipolars, not among bipolars. The consequences of different selection criteria for the composition of proband groups are discussed.     

The reliability of case register diagnoses: a birth cohort analysis

Background: Few studies assess the reliability of case register diagnoses, despite their widespread use in psychiatric research. This study investigates case register diagnostic reliability in comparison to casenote derived diagnoses in a birth cohort. Methods: Diagnostic information from the case register and casenotes of 449 individuals was extracted. The incident and lifetime register diagnoses were compared with those derived from the casenotes. Results: Inter-rater reliability was good (kappa = 0.71). Agreement between casenote and incident register diagnosis was moderate (kappa = 0.52), as was agreement between casenote and register lifetime diagnosis (kappa = 0.58). Case register diagnoses were insufficiently accurate to stand alone. Case register diagnoses for organic disorder, schizophrenia, alcoholism, learning disability, personality disorder and transient or no psychiatric disorder were reliable enough for the case register to act as a useful screening instrument. The case register was not acceptable, even as a screening instrument, for the diagnoses of neurotic or affective disorders. Conclusions: Studies relying only on case register diagnoses may be flawed if diagnoses are not independently verified. National statistics derived from case register data, especially for neurosis and affective disorder, may be unreliable. Accepted: 25 November 1999     

Comparison of hospital-treated personality disorders and personality disorders in a general population sample

The distribution of personality disorders (PDs) was explored in hospital-treated subjects and in a population subsample. This study forms a part of the Northern Finland 1966 Birth Cohort study. Hospital case records of psychiatric treatment periods of all cohort members (n=11,017) were reviewed and re-checked against DSM-III-R criteria. A subsample of the cohort members living in Oulu (n=1609) were invited to a two-stage psychiatric field survey with Structured Clinical Interview for DSM-III-R (SCID) as a diagnostic method. The most common PDs in hospital-treated sample were cluster B PDs (erratic). In the population subsample, cluster C PDs (anxious) formed the majority.     

The reliability and validity of general psychotic rating scales with people with mild and moderate intellectual disabilities: an empirical investigation

Background Whilst assessment tools have been developed to diagnose schizophrenia in people with mild intellectual disabilities (IDs), little attention has been paid to developing reliable and valid dimensional measures of psychotic experiences with this population. This study investigates the reliability and validity of two such measures developed for the general adult psychiatric population, the Positive and Negative Syndrome Scale (PANSS) and the Psychotic Symptom Rating Scales (PSYRATS), with a population of adults with mild IDs. Method Sixty-two adults with mild IDs were interviewed using the PANSS and PSYRATS, and independently interviewed using the Psychiatric Assessment Schedule – Adults with Developmental Disability (PAS-ADD) to obtain psychiatric diagnoses to the criteria of the International Classification of Diseases – Tenth Revision (ICD-10). On the basis of ICD-10 diagnosis, participants were divided into three groups: psychosis (n = 11); other mental health problem (n = 14); no mental health problem (n = 37). PANSS and PSYRATS subscale scores were compared across these three groups and were correlated with PAS-ADD symptom scores across a number of PAS-ADD symptom domains. Results All PANSS and PSYRATS subscales showed adequate internal reliability, largely good test-retest reliability, and logical inter-correlations between subscales. The PANSS positive symptoms and the PSYRATS auditory hallucinations subscales differentiated between the psychosis group and the other groups; the PANSS general symptoms subscale differentiated between the psychosis and no mental health problem groups; and the PANSS negative symptoms and the PSYRATS delusions subscales did not differentiate between the three groups. Conclusions The PANSS and PSYRATS are promising measures for use with people with mild IDs and psychotic experiences, although further investigation of items relating to negative symptoms and delusions is warranted.