Schizophrenia and mental handicap: an historical review, with implications for further research

Retinitis pigmentosa and schizophrenia

There have been previous suggestions in the literature of a link between schizophrenia and retinitis pigmentosa (RP) or its associated syndromes. In this article, we describe two cases of schizophrenía and two cases of delusional disorder occurring in patients with RP. We explore possible reasons for an association between RP and schizophrenia including shared genetic predisposition, sensory deprivation, coarse brain disease and retinoid dysregulation. Awareness of an association may help to direct future research into the aetiology of these disorders, especially in the areas of neurochemistry and medical genetics.

Prevalence of co-occurring psychiatric disorders in adults and adolescents with intellectual disability: A systematic review and meta-analysis

BACKGROUND

Subjects with intellectual disability (ID) are vulnerable to experience psychiatric disorders. The present authors performed a systematic review and meta-analysis to estimate the prevalence of co-occurring psychiatric disorders, excluding co-occurring autism spectrum disorders, in subjects with intellectual disability.

METHOD

The present authors performed a random-effects meta-analysis of the prevalence of psychiatric disorders in adults and adolescents with intellectual disability.

RESULTS

Twenty-two studies were included. The pooled prevalence of any co-occurring psychiatric disorders in intellectual disability was 33.6% (95% CI: 25.2%-43.1%) with high heterogeneity but no publication bias. Prevalence was lower in population-based studies, in studies that used ICD criteria for the psychopathology and in studies with low risk of bias. The prevalence was higher in mild, moderate and severe intellectual disability than in profound intellectual disability.

CONCLUSIONS

Psychiatric disorders are common in subjects with intellectual disability, and the present authors found that clinical and methodological moderators affect the pooled prevalence.

Predictors of psychotic symptoms among young people with special educational needs

BACKGROUND

Psychotic symptoms and psychotic disorders occur at increased rates in adults with intellectual disability, including borderline intellectual functioning, compared with the general population. Little is known about the development of such symptoms in this population.AimsTo examine whether clinical factors predictive of psychotic disorder in a familial study of schizophrenia also apply to those with intellectual disability.

METHOD

Adolescents with special educational needs (SEN) were assessed with the Structured Interview for Schizotypy (SIS) and Childhood Behavioural Checklist (CBCL). These scores were used to prospectively divide participants based on their anticipated risk for psychotic disorder. A subsample were reassessed three times over 6 years, using the Positive and Negative Syndrome Scale (PANSS).

RESULTS

The SEN group were more symptomatic than controls throughout (Cohen's d range for PANSS subscale scores: 0.54-1.4, all P < 0.007). Over 6 years of follow-up, those above the SIS and CBCL cut-off values at baseline were more likely than those below to display morbid positive psychotic symptoms (odds ratio, 3.5; 95% CI 1.3-9.0) and develop psychotic disorder (odds ratio, 11.4; 95% CI 2.6-50.1). Baseline SIS and CBCL cut-off values predicted psychotic disorder with sensitivity of 0.67, specificity of 0.85, positive predictive value of 0.26 and negative predictive value of 0.97.

CONCLUSIONS

Adolescents with SEN have increased psychotic and non-psychotic symptoms. The personality and behavioural features associated with later psychotic disorder in this group are similar to those in people with familial loading. Relatively simple screening measures may help identify those in this vulnerable group who do and do not require monitoring for psychotic symptoms.Declaration of interestNone.

Compulsory community treatment to reduce readmission to hospital and increase engagement with community care in people with mental illness: a systematic review and meta-analysis

BACKGROUND

Compulsory community treatment (CCT) aims to reduce hospital readmissions among people with mental illness. However, research examining the usefulness of CCT is inconclusive. We aimed to assess the effectiveness of CCT in reducing readmission and length of stay in hospital and increasing community service use and treatment adherence.

METHODS

For this systematic review and meta-analysis, we searched three databases (PsycINFO, MEDLINE and Embase) for quantitative studies on CCT published in English between Jan 1, 1806, and Jan 4, 2018. We included both randomised and non-randomised designs that compared CCT with no CCT, and pre-post designs that compared patients before and after CCT. Studies were eligible if they had been peer-reviewed, if 50% or more of patients had severe mental illness, and if CCT was the intervention. Trials in which CCT was used in response to a criminal offence were excluded. We extracted data on study characteristics and length of follow-up, patient-level data on diagnosis, age, sex, race, and admission history, and outcomes of interest (readmission to hospital, inpatient bed-days, community service use, and treatment adherence) for meta-analysis, for which we extracted summary estimates. We used a random-effects model to compare disparate outcome measures and convert effect size statistics into standardised mean differences. This systematic review is registered with PROSPERO, number CRD42018086232.

FINDINGS

Of 1931 studies identified, 41 (2%) met inclusion criteria and had sufficient data for analysis. Before and after CCT comparisons showed significant large effects on readmission to hospital (standardised mean difference 0·80, 95% CI 0·53-1·08; I²=94·74), use of community services (0·83, 0·46-1·21; I²=87·26), and treatment adherence (2·12, 1·69-2·55; I²=0), and a medium effect on inpatient bed-days (0·66, 0·46-0·85; I²=94·12). Contemporaneous controlled comparison studies (randomised and non-randomised) showed no significant effect on readmission, inpatient bed-days, or treatment adherence, but a moderate effect on use of community services (0·38, 0·19-0·58; I²=96·92). A high degree of variability in study quality was found, with observational study ratings ranging from three to nine. Bias most frequently centred on poor comparability between CCT and control participants.

INTERPRETATION

We found no consistent evidence that CCT reduces readmission or length of inpatient stay, although it might have some benefit in enforcing use of outpatient treatment or increasing service provision, or both. Future research should focus on why some people do not engage with treatment offered and on enhancing quality of the community care available. Shortcomings of this study include high levels of variability between studies and variation in study quality.

FUNDING

National Institute for Health Research.

Learning disability psychiatry – the future of services

Distinctions between mental illness and learning disability have existed since the last century (Pinel, 1801; Ireland, 1877). The conditions have been accepted as coexisting in the same individual since the beginning of this century (Kraepelin, 1902). More recent papers have investigated the frequency of their coexistence and concluded that most psychiatric disorders are more common in those with learning disability than the general population (Turner, 1989).

Psychiatric illness and learning disability: a dual diagnosis

The prevalence of moderate to profound learning disability is roughly 3 per 1000 and of mild learning disability about 3 per hundred (Abramowicz & Richardson, 1975). There are estimated to be more than 120 million people with learning disability worldwide.

Development of a Multidisciplinary Care Pathway for a Specialist Learning Disability Inpatient Treatment and Assessment Unit

This paper describes the development of a multidisciplinary care pathway for an inpatient assessment and treatment unit, for people with learning disabilities and mental health problems or challenging behaviour. Early results suggest the care pathway development has been useful in a number of areas including risk management, assessment of capacity developing care plans, the routine use of outcome measures and increased throughput. Formal documentation has been developed to support the pathway and deficits in provision of specific service areas are now easily identified.

"Intellectual developmental disorders": reflections on the international consensus document for redefining "mental retardation-intellectual disability" in ICD-11

PURPOSE

The debate as to whether intellectual disability (ID) should be conceptualized as a health condition or as a disability has intensified as the revision of World Health Organization's (WHO's) International Classification of Diseases (ICD) is being finalized. Defining ID as a health condition is central to retaining it in ICD, with significant implications for health policy and access to health services. The purpose of this paper is to include some reflections on the consensus document produced by the first WHO Working Group on the Classification of MR (WHO WG-MR) and on the process that was followed to realize it. The consensus report was the basis for the development of official recommendations sent to the WHO Advisory Group for ICD-11.

DESIGN/METHODOLOGY/APPROACH

A mixed qualitative approach was followed in a series of meetings leading to the final consensus report submitted to the WHO Advisory group. These recommendations combined prior expert knowledge with available evidence; a nominal approach was followed throughout with face-to-face conferences.

FINDINGS

The WG recommended a synonym set ("synset") ontological approach to the conceptualisation of this health condition underlying a clinical rationale for its diagnosis. It proposed replacing MR with Intellectual Developmental Disorders (IDD) in ICD-11, defined as "a group of developmental conditions characterized by a significant impairment of cognitive functions, which are associated with limitations of learning, adaptive behaviour and skills". The WG further advised that IDD be included under the parent category of neurodevelopmental disorders, that current distinctions (mild, moderate, severe and profound) be continued as severity qualifiers, and that problem behaviours removed from its core classification structure and instead described as associated features.

ORIGINALITY/VALUE

Within the ID/IDD synset two different names combine distinct aspects under a single construct that describes its clinical as well as social, educational and policy utilities. The single construct incorporates IDD as a clinical meta-syndrome, and ID as its functioning and disability counterpart. IDD and ID are not synonymous or mirror concepts as they have different scientific, social and policy applications. New diagnostic criteria for IDD should be based on a developmental approach, which accounts for the complex causal factors known to impact the acquisition of specific cognitive abilities and adaptive behaviours. The paper focuses on a new clinical framework for the diagnosis of IDD that also includes and complements the existing social, educational and policy components inherent in ID.

Examining the psychometrics of the Psychopathology Inventory for Mentally Retarded Adults-II for individuals with mild and moderate intellectual disabilities

With growing recognition of the occurrence of psychological disorders in individuals with intellectual disability (ID), researchers and clinicians alike have placed emphasis on developing measures to assess for psychopathologies in this population. Despite an increased interest in the topic, there is still a dearth of psychometrically robust measures available to assess for psychopathology in adults with mild and moderate ID. The purpose of this study was to examine the psychometric properties of a revised measure for psychopathology in individuals with mild and moderate ID, the Psychopathology Inventory for Mentally Retarded Adults - second edition (PIMRA-II). Internal consistency, inter-rater reliability, and test-retest reliability were investigated. Validity was studied via convergent validity by comparing the PIMRA-II to the Assessment of Dual Diagnosis (ADD) and via discriminate validity by comparing the PIMRA-II to the Social Performance Survey Schedule (SPSS) prosocial scores. Lastly, an exploratory factor analysis was conducted to determine the factor structure of the scale.

Interaction of neurodevelopmental pathways and synaptic plasticity in mental retardation, autism spectrum disorder and schizophrenia: implications for psychiatry

OBJECTIVES

Schizophrenia (SCZ), autism spectrum disorder (ASD) and mental retardation (MR) are psychiatric disorders with high heritability. They differ in their clinical presentation and in their time course of major symptoms, which predominantly occurs for MR and ASD during childhood and for SCZ during young adult age. Recent findings with focus on the developmental neurobiology of these disorders emphasize shared mechanisms of common origin. These findings propose a continuum of genetic risk factors impacting on synaptic plasticity with MR causing impairments in global cognitive abilities, ASD in social cognition and SCZ in both global and social cognition.

METHODS

We assess here the historical developments that led to the current disease concepts of the three disorders. We then analyse, based on the functions of genes mutated in two or three of the disorders, selected mechanisms shared in neurodevelopmental pathways and synaptic plasticity.

RESULTS

The analysis of the psychopathological constructs supports the existence of three distinct clinical entities but also elaborates important associations. Similarly, there are common mechanisms especially in global and social cognition.

CONCLUSIONS

We discuss implications from this integrated view on MR, ASD and SCZ for child & adolescent and adult psychiatry in pathophysiology and research perspectives.

Withdrawal of antipsychotic drugs from adults with intellectual disabilities

Objectives: There is a view that antipsychotic drugs can be successfully withdrawn from people with intellectual disabilities with resultant health gain. This study critically examines whether antipsychotic drug withdrawal is beneficial.

Methods: 119 adults with intellectual disabilities were included in a programme of antipsychotic drug withdrawal.

Results: The clinical outcomes of this programme are poor. Only 7.6% completely withdrew from antipsychotic drugs, and 48.7% experienced onset/deterioration in problem behaviours or mental ill-health. Significant drug side effects with the introduction of new drugs were experienced by 23.3%. Resultant mean antipsychotic drug doses were higher compared with those at the start of the programme. The cost to the intellectual disabilities psychiatric service (over and above that of routine psychiatric care) was £258,050 (€391,693), and the human cost was considered high. Primary care, social care and family costs were not calculated. The only specific factors found to be associated with poor outcome were increased severity of intellectual disabilities and female gender.

Conclusions: The successful role of antipsychotic drugs in the management of problem behaviours in people who do not have verbal communication skills may relate to the pathoplastic effect of intellectual disabilities on clinical presentation, with problem behaviours being markers of eg. psychosis and anxiety disorders. Our original findings challenge the view that routine withdrawal of antipsychotic drugs is good practice; we reinterpret the existing literature, and recommend caution and vigilance in pharmacotherapy.

A genome wide survey supports the involvement of large copy number variants in schizophrenia with and without intellectual disability

BACKGROUND

Copy number variants (CNVs) have been shown to play a role in schizophrenia and intellectual disability.

METHODS

We compared the CNV burden in 66 patients with intellectual disability and no symptoms of psychosis (ID-only) with the burden in 64 patients with intellectual disability and schizophrenia (ID + SCZ). Samples were genotyped on three plates by the Broad Institute using the Affymetrix 6.0 array.

RESULTS

For CNVs larger than 100 kb, there was no difference in the CNV burden of ID-only and ID + SCZ. In contrast, the number of duplications larger than 1 Mb was increased in ID + SCZ compared to ID-only. We detected seven large duplications and two large deletions at chromosome 15q11.2 (18.5-20.1 Mb) which were all present in patients with ID + SCZ. The involvement of this region in schizophrenia was confirmed in Scottish samples from the ISC study (N = 2,114; 1,130 cases and 984 controls). Finally, one of the patients with schizophrenia and low IQ carrying a duplication at 15q11.2, is a member of a previously described pedigree with multiple cases of mild intellectual disability, schizophrenia, hearing impairment, retinitis pigmentosa and cataracts. DNA samples were available for 11 members of this family and the duplication was present in all 10 affected individuals and was absent in an unaffected individual.

CONCLUSIONS

Duplications at 15q11.2 (18.5-20.1 Mb) are highly prevalent in a severe group of patients characterized by intellectual disability and comorbid schizophrenia. It is also associated with a phenotype that includes schizophrenia, low IQ, hearing and visual impairments resembling the spectrum of symptoms described in "ciliopathies."

Psychiatrists' knowledge, training and attitudes regarding the care of individuals with intellectual disability

BACKGROUND

Psychiatrists are responsible for providing proper care for people with intellectual disability who have psychiatric disorders. This study examined psychiatrists' perceptions of their own training, knowledge and therapeutic skills, as well as their attitudes towards this population.

METHODS

Questionnaires were distributed to 679 psychiatrists working within the public sector in Israel.

RESULTS

Completed questionnaires were returned from 256 psychiatrists (38% response rate). Most (90%) participants reported having had limited training in the diagnosis and treatment of people with intellectual disabilities, while between 34% and 72% reported having inadequate knowledge in specific areas.

CONCLUSION

The findings of limited training and self-perceived inadequate knowledge are at least partially explained by the service model, wherein people with intellectual disabilities are cared for by general mental health services. The identified inadequacies could be overcome through the implementation of a model in which specially trained psychiatrists are deployed within generic services.

Longitudinal gray matter change in young people who are at enhanced risk of schizophrenia due to intellectual impairment

BACKGROUND

Existing studies of brain structural changes before the onset of schizophrenia have considered individuals with either familial risk factors or prodromal symptomatology. We aimed to determine whether findings from these studies are also applicable to those at enhanced risk of developing schizophrenia for another reason-intellectual impairment.

METHODS

Participants with intellectual impairment (mean IQ: 78.2) received magnetic resonance imaging of the brain at baseline (mean age: 16 years old) and again 6 years later. The Positive and Negative Syndrome Scale was used to assess psychotic symptoms. Participants were dichotomized using their Positive and Negative Syndrome Scale scores at follow-up and gray matter changes were compared between the groups using tensor based morphometry and semiautomated region of interest analysis.

RESULTS

Forty-six individuals had scans of sufficient quality to be included in the study. The tensor based morphometry analyses revealed that those with psychotic symptoms at follow-up showed significantly greater gray matter reductions over 6 years in the medial temporal lobes bilaterally. Region of interest analyses revealed that those individuals with psychotic symptoms at follow-up showed a reduced right hippocampal volume at age 16 and reduced bilateral hippocampal volumes at follow-up.

CONCLUSIONS

This unique study of individuals vulnerable to schizophrenia due to intellectual impairment highlights aberrant development in the medial temporal lobe associated with the occurrence of psychotic symptoms. These developmental changes are also evident in populations at enhanced risk of schizophrenia for familial and symptomatic reasons, suggesting they are central to the development of the disorder regardless of the nature of the vulnerability state.

Copy number variants of schizophrenia susceptibility loci are associated with a spectrum of speech and developmental delays and behavior problems

PURPOSE

: Recently, molecular cytogenetic techniques have identified novel copy number variants in individuals with schizophrenia. However, no large-scale prospective studies have been performed to characterize the broader spectrum of phenotypes associated with such copy number variants in individuals with unexplained physical and intellectual disabilities encountered in a diagnostic setting.

METHODS

: We analyzed 38,779 individuals referred to our diagnostic laboratory for microarray testing for the presence of copy number variants encompassing 20 putative schizophrenia susceptibility loci. We also analyzed the indications for study for individuals with copy number variants overlapping those found in six individuals referred for schizophrenia.

RESULTS

: After excluding larger gains or losses that encompassed additional genes outside the candidate loci (e.g., whole-arm gains/losses), we identified 1113 individuals with copy number variants encompassing schizophrenia susceptibility loci and 37 individuals with copy number variants overlapping those present in the six individuals referred to our laboratory for schizophrenia. Of these, 1035 had a copy number variant of one of six recurrent loci: 1q21.1, 15q11.2, 15q13.3, 16p11.2, 16p13.11, and 22q11.2. The indications for study for these 1150 individuals were diverse and included developmental delay, intellectual disability, autism spectrum, and multiple congenital anomalies.

CONCLUSION

: The results from our study, the largest genotype-first analysis of schizophrenia susceptibility loci to date, suggest that the phenotypic effects of copy number variants associated with schizophrenia are pleiotropic and imply the existence of shared biologic pathways among multiple neurodevelopmental conditions.

Amygdala volume in a population with special educational needs at high risk of schizophrenia

BACKGROUND

The mildly learning disabled population has a three-fold elevated risk for schizophrenia. It has been proposed that in some individuals this cognitive limitation is a pre-psychotic manifestation of early onset schizophrenia. We examined clinical and neuroanatomical measures of a putative extended phenotype of schizophrenia in an adolescent population receiving special educational assistance. We predicted that people with intellectual impairment and schizotypal features would exhibit amygdala volume reduction as one of the neuroanatomical abnormalities associated with schizophrenia.

METHOD

Assessment by clinical interview, neuropsychological assessment and magnetic resonance imaging scanning was carried out in 28 intellectually impaired individuals identified as being at elevated risk of schizophrenia due to the presence of schizotypal traits, 39 intellectually impaired controls and 29 non-intellectually impaired controls. Amygdala volume was compared in these three groups and the relationship between symptomatology and amygdala volume investigated.

RESULTS

Right amygdala volume was significantly increased in the elevated risk group compared with the intellectually impaired controls (p=0.05). A significant negative correlation was seen between left amygdala volume and severity of negative symptoms within this group (p<0.05), but not in either control group.

CONCLUSIONS

Intellectually impaired subjects judged to be at elevated risk of schizophrenia on the basis of clinical assessment exhibit structural imaging findings which distinguish them from the generality of learning disabled subjects. Within this population reduced amygdala volume may be associated with negative-type symptoms and be part of an extended phenotype that reflects particularly elevated risk and/or early manifestations of the development of psychosis.

A recurrent 16p12.1 microdeletion supports a two-hit model for severe developmental delay

We report the identification of a recurrent 520-kbp 16p12.1 microdeletion significantly associated with childhood developmental delay. The microdeletion was detected in 20/11,873 cases vs. 2/8,540 controls (p=0.0009, OR=7.2) and replicated in a second series of 22/9,254 cases vs. 6/6,299 controls (p=0.028, OR=2.5). Most deletions were inherited with carrier parents likely to manifest neuropsychiatric phenotypes (p=0.037, OR=6). Probands were more likely to carry an additional large CNV when compared to matched controls (10/42 cases, p=5.7×10^-5, OR=6.65). Clinical features of cases with two mutations were distinct from and/or more severe than clinical features of patients carrying only the co-occurring mutation. Our data suggest a two-hit model in which the 16p12.1 microdeletion both predisposes to neuropsychiatric phenotypes as a single event and exacerbates neurodevelopmental phenotypes in association with other large deletions or duplications. Analysis of other microdeletions with variable expressivity suggests that this two-hit model may be more generally applicable to neuropsychiatric disease.

Neurological disorders in schizophrenia

Schizophrenia (SZ) is a complex, heterogeneous, and disabling psychiatric disorder that impairs multiple aspects of human cognitive, perceptual, emotional, and behavioral functioning. SZ is relatively frequent (prevalence around 1%), with onset usually during adolescence or early adulthood, and has a deteriorating course. The rapidly growing area of neuroimaging research has has found clear evidence of many cortical and subcortical abnormalities in individuals with SZ. In this article the most recent findings from multiple studies on neurological disorders in SZ are reviewed, and the authors make a strong argument for a neurological basis of the schizophrenic process.

Progressive temporal lobe grey matter loss in adolescents with schizotypal traits and mild intellectual impairment

Adolescents with mild intellectual impairment are known to have an increased risk of schizophrenia compared to the general population. However, little is known regarding the association between potential risk markers for later schizophrenia within this population. We therefore set out to examine the association between schizotypal traits and progressive grey matter loss in adolescents with mild intellectual impairment. Ninety-eight adolescents receiving educational assistance were divided into two groups based on their degree of schizotypal features, measured using the Structured Interview for Schizotypy (SIS). Each participant received two structural magnetic resonance imaging scans approximately 16 months apart. Changes over time in the voxel-wise presentation of tissue were evaluated using tensor based morphometry. Those with marked schizotypal features exhibited significantly greater grey matter losses in the left medial temporal lobe than those without. Three focal locations were identified, two within the left amygdala and one in the left parahippocampal gyrus. Thus, adolescents with cognitive impairment and schizotypal features show changes in brain structure over time, changes that are consistent with those identified in other high risk populations. Medial temporal grey matter loss may therefore represent a common neuroanatomical substrate of risk for schizophrenia, common to familial, prodromal and cognitive high risk groups.

Phenotyping psychosis: room for neurocomputational and content-dependent cognitive endophenotypes?

INTRODUCTION

The endophenotype research strategy aims at reducing complex clinical phenomena to reveal a more tractable mapping to underlying genes. Cognitive dysfunctions have been widely pursued as target endophenotype in schizophrenia. We critically discuss the promise and limitations of this approach.

METHODS

Relevant theoretical and empirical issues on genes and behaviour, neurocognitive structure and psychopathology were selectively reviewed and discussed.

RESULTS

Some important inherent limitations of the current cognitive endophenotype approach were identified. These include reliance on (1) classic neuropsychology; (2) deficit measures; and (3) a general information processing approach with the use of content-independent, neutral stimuli. As a result, many current cognitive endophenotypes are likely to overlap and converge with general cognitive impairments, which may be shared with other disorders.

CONCLUSIONS

We propose three novel directions for further psychosis endophenotype research: (1) in addition to such content-independent computational processes, which operate in a similar way regardless of the stimuli, it is important to consider the potential roles of "content-dependent endophenotypes", which operate on different stimuli in consistently different manners. Advances in cognitive studies suggest there may be evolutionarily important aspects of cognition which are content-dependent. We propose that both content-independent and content-dependent processes should be addressed in psychosis research. (2) In line with the emphasis on content, close attention should be paid to the study of "psychopathological endophenotypes" in addition to cognitive endophenotypes. (3) "Neurocomputational endophenotypes" may be defined by parsing cognitive processes into "subsystems" with specific computational processing algorithms and considering key computational parameters suggested from these models. These potential "neurocomputational endophenotypes" (such as neuronal noise, synaptic learning algorithms) are potentially intermediate variables located between the levels of cognition and neurobiology.

Catatonia and autism: a historical review, with implications for electroconvulsive therapy

Current autism research is historically separated from catatonia and other childhood psychotic disorders, although catatonia and autism share several common symptoms (mutism, echolalia, stereotypic speech and repetitive behaviors, posturing, grimacing, rigidity, mannerisms, and purposeless agitation). Electroconvulsive therapy (ECT) effectively treats catatonia and catatonia-related conditions of intractable compulsions, tics, and self-injury in people with autism. We assess the incidence of catatonic symptoms in autism, examine emerging ECT indications in people with autism and related developmental disorders, and encourage ethical debate and legal-administrative action to assure equal access to ECT for people with autism.

Cognitive and emotional associations to positive schizotypy during adolescence

BACKGROUND

Sub-clinical symptoms of psychosis such as hallucinations and delusions, known as positive schizotypy, constitute one of the strongest predictive factors for adult psychotic disorders. Recent cognitive models suggest that the expression of positive schizotypy is associated with depression, anxiety, metacognitive beliefs and self-monitoring deficits. In this study, we present empirical data on the relationships positive schizotypy hold with both emotional and cognitive factors.

METHODS

A sample of 163 adolescents (77 females) participated in this study (mean age 15.3, 12-18 years). Subjects filled out self-report questionnaires assessing the emotional dimensions of depression and anxiety, as well as metacognitive beliefs. Self-monitoring skills were assessed using an action monitoring paradigm sensitive to dysfunctions associated with psychosis-proneness. Multivariate regression models were employed to examine emotional and cognitive contributions to positive schizotypy during adolescence.

RESULTS

Analyses revealed that dimensions of depression, anxiety, and metacognitive beliefs significantly correlated with the expression of positive schizotypy. When accounting for the effects of depression and metacognitive beliefs in adolescents reporting hallucinations, self-monitoring dysfunctions seemed to represent a significant factor in the expression of positive schizotypy.

CONCLUSION

The present results suggest that the expression of positive schizotypy during adolescence is modulated by emotional factors of depression and anxiety, as well as metacognitive beliefs and self-monitoring dysfunctions. The current data lend some evidence that supports the cognitive-developmental account of positive symptom formation before the onset of a psychotic disorder.

Intellectual disability co-occurring with schizophrenia and other psychiatric illness: population-based study

BACKGROUND

The epidemiology of intellectual disability co-occurring with schizophrenia and other psychiatric illness is poorly understood. The separation of mental health from intellectual disability services has led to a serious underestimation of the prevalence of dual diagnosis, with clinicians ill-equipped to treat affected individuals.

AIMS

To estimate the prevalence of dual diagnosis and describe its clinical profile.

METHOD

The Western Australian population-based psychiatric and intellectual disability registers were cross-linked (total n=245,749).

RESULTS

Overall, 31.7% of people with an intellectual disability had a psychiatric disorder; 1.8% of people with a psychiatric illness had an intellectual disability. Schizophrenia, but not bipolar disorder and unipolar depression, was greatly over-represented among individuals with a dual diagnosis: depending on birth cohort, 3.7-5.2% of those with intellectual disability had co-occurring schizophrenia. Pervasive developmental disorder was identified through the Intellectual Disability Register and is therefore limited to individuals with intellectual impairment. None the less, pervasive developmental disorder was more common among people with a dual diagnosis than among individuals with intellectual disability alone. Down syndrome was much less prevalent among individuals with a dual diagnosis despite being the most predominant cause of intellectual disability. Individuals with a dual diagnosis had higher mortality rates and were more disabled than those with psychiatric illness alone.

CONCLUSIONS

The facility to combine records across administrative jurisdictions has enhanced our understanding of the epidemiology of dual diagnosis, its clinical manifestations and aetiological implications. In particular, our results are suggestive of a common pathogenesis in intellectual disability co-occurring with schizophrenia.

Psycho-educational groups for people with a dual diagnosis of psychosis and mild intellectual disability: a preliminary study

There have been considerable developments in psychosocial interventions for people with psychosis, but few studies on their application to individuals with a dual diagnosis of intellectual disability and psychosis. This includes the use of psycho-educational groups to develop a greater understanding of the impact of psychosis. Eight individuals with a dual diagnosis of mild to borderline intellectual disabilities and psychosis took part in a psycho-education group supported by a carer. Measures of knowledge and self-esteem were completed pre- and post-group. All participants completed the programme and measures of psychosis knowledge showed increases post-group. The participants were able to understand the concept of psychosis, the need for medication, the role of stress and early signs of relapse. This approach may help participants to have a better understanding of their condition and prepare them to cope better in the future.

Increased right prefrontal cortical folding in adolescents at risk of schizophrenia for cognitive reasons

BACKGROUND

Two of the strongest predictors of later schizophrenia in the Edinburgh High Risk Study (EHRS) were the presence of schizotypal features and increased right prefrontal lobe cortical folding. We examined the association between these measures in adolescents at enhanced risk of developing schizophrenia due to cognitive impairment.

METHODS

One hundred forty-three adolescents receiving special education were divided into two groups using the cut-off on the Structured Interview for Schizotypy (SIS) which optimally predicted later schizophrenia in the EHRS. Each participant received a structural magnetic resonance imaging scan. Prefrontal tissue volumes and a standard measure of cortical folding, the gyrification index (GI), were determined automatically using automated (A)-GI methodology.

RESULTS

Those who scored above the SIS cut-off had a significantly higher right prefrontal lobe GI compared to those below the cut-off (F = 4.72, p = .03). GI correlated strongly with prefrontal tissue volumes, although when prefrontal volume was added as a covariate to the GI analysis a trend towards a group difference remained evident.

CONCLUSIONS

The level of schizotypal cognitions among adolescents with cognitive impairment identifies a group with the same pattern of cortical folding seen in those with familial risk factors who later develop the disorder. Increased right prefrontal GI may reflect disordered connectivity in individuals with the greatest risk of developing schizophrenia.

Schizotypal cognitions as a predictor of psychopathology in adolescents with mild intellectual impairment

BACKGROUND

There is evidence to suggest that among young people with mild intellectual disability there are those whose cognitive difficulties may predict the subsequent manifestation of a schizophrenic phenotype. It is suggested that they may be detectable by simple means.

AIMS

To gain adequate cooperation from educational services, parents and students so as to recruit a sufficiently large sample to test the above hypothesis, and to examine the hypothesis in the light of the findings.

METHOD

The sample was screened with appropriate instruments, and groups hypothesised as being likely or not likely to have the phenotype were compared in terms of psychopathology and neuropsychology.

RESULTS

Simple screening methods detect a sample whose psychopathological and neuropsychological profile is consistent with an extended phenotype of schizophrenia.

CONCLUSIONS

Difficulties experienced by some young people with mild and borderline intellectual disability are associated with enhanced liability to schizophrenia. Clinical methods can both identify those with this extended phenotype and predict those in whom psychosis will occur.

Cognitive and behavioural therapy of voices for with patients intellectual disability: two case reports

BACKGROUND

Two case studies are presented to examine how cognitive behavioural therapy (CBT) of auditory hallucinations can be fitted to mild and moderate intellectual disability.

METHODS

A 38-year-old female patient with mild intellectual disability and a 44-year-old male patient with moderate intellectual disability, both suffering from persistent auditory hallucinations, were treated with CBT. Patients were assessed on beliefs about their voices and their inappropriate coping behaviour to them. The traditional CBT techniques were modified to reduce the emphasis placed on cognitive abilities. Verbal strategies were replaced by more concrete tasks using role-playing, figurines and touch and feel experimentation.

RESULTS

Both patients improved on selected variables. They both gradually managed to reduce the power they attributed to the voice after the introduction of the therapy, and maintained their progress at follow-up. Their inappropriate behaviour consecutive to the belief about voices diminished in both cases.

CONCLUSION

These two case studies illustrate the feasibility of CBT for psychotic symptoms with intellectually disabled people, but need to be confirmed by more stringent studies.

Velocardiofacial syndrome

Velocardiofacial syndrome (VCFS) is the most common known microdeletion in humans. It is also the most common known genetic risk factor for schizophrenia. The aim of this article is to describe the clinical characteristics of the syndrome, with emphasis on the myriad psychiatric disorders and abnormal behaviors from a developmental perspective. In addition, the possible pathways that lead to the psychotic symptoms and cognitive deficits are discussed. Guidelines are suggested to alert clinicians to the possibility of the presence of VCFS, and the cumulative clinical experience and limited research on psychiatric treatments for VCFS are presented. There is an urgent need to conduct treatment trials in this high-risk population.

Psychosis and adults with intellectual disabilities. Prevalence, incidence, and related factors

OBJECTIVE

To determine the point prevalence, incidence, and remission over a 2-year period of psychosis in adults with intellectual disabilities, and to investigate demographic and clinical factors hypothesised to be associated with psychosis.

METHOD

A population-based cohort of adults with intellectual disabilities (n = 1,023) was longitudinally studied. Comprehensive face-to-face mental health assessments to detect psychosis, plus review of family physician, psychiatric, and psychology case notes were undertaken at two time points, 2 years apart.

RESULTS

Point prevalence is 2.6% (95% CI = 1.8-3.8%) to 4.4% (95% CI = 3.2-5.8%), dependant upon the diagnostic criteria employed. Two-year incidence is 1.4% (95% CI = 0.6-2.6), and for first episode is 0.5% (95% CI = 0.1-1.3). Compared with the general population, the standardised incidence ratio for first episode psychosis is 10.0 (95% CI = 2.1-29.3). Full remission after 2 years is 14.3%. Visual impairment, previous long-stay hospital residence, smoking, and not having epilepsy were independently associated with psychosis, whereas other factors relevant to the general population were not.

CONCLUSIONS

The study of psychosis in persons with intellectual disabilities benefits the population with intellectual disabilities, and advances the understanding of psychosis for the general population. Mental health professionals need adequate knowledge in order to address the high rates of psychosis in this population.

Schizophrenia spectrum disorders in people with intellectual disabilities

PURPOSE OF REVIEW

To examine most recently published studies of schizophrenia spectrum disorders in people with intellectual disabilities.

RECENT FINDINGS

Studies that have been published in the review period have advanced understanding of the epidemiology, presentation, assessment, suspected neuropathology, genetics and treatment of, and service issues relating to, schizophrenia spectrum disorders in people with intellectual disabilities.

SUMMARY

The number of published studies investigating schizophrenia spectrum disorders in people with intellectual disabilities continues to increase slowly. The evidence base, however, needs to be strengthened, particularly by randomized controlled trials in pharmacotherapy, psychosocial interventions and service delivery.

Hereditary spastic paraparesis and psychosis

Hereditary spastic paraparesis (HSP) is characterized by progressive spasticity and weakness of the legs with or without additional abnormalities. Reports of psychiatric disorders in patients with HSP are limited to mood disturbances rather than to psychosis. We had noted significant psychotic illness in several patients recruited to a survey of HSP in Ireland and therefore set about examining the frequency and nature of psychosis in our patients with HSP. Cases with HSP and psychotic illness were identified from a nationwide epidemiological and clinical study. Psychiatric case notes were reviewed and Operational Diagnostic Criteria Checklist (OPCRIT) applied. Six patients from four families with HSP had evidence of psychosis in addition to paraparesis. OPCRIT diagnoses were 'narrow schizophrenia' (n = 2), 'broad schizophrenia' (n = 2) and 'schizo-affective/manic disorder' (n = 2). Patients were from families with Kjellin's syndrome and SPG4-HSP but not other kindreds and psychosis was not evident in family members without HSP. We found a higher than expected rate of psychosis in the Irish HSP population. Two groups of HSP patients may have increased risk of developing psychosis: those with Kjellin's syndrome and those with SPG4-HSP.

Schizophrenia in an adult with 6p25 deletion syndrome

Chromosomal deletions at 6p25-p24 are rare findings in patients with developmental delay. There is limited information about the adult phenotype. We present a 36-year-old patient with schizophrenia, mild mental retardation, progressive hearing deficits, and characteristic facial features. Ocular (Axenfeld-Rieger anomaly) abnormalities were diagnosed in infancy; vision, however, has remained unimpaired. There were no other major congenital anomalies. Brain imaging showed only minor changes. There was no family history of intellectual deficits or psychosis. Karyotyping revealed a 6p25 deletion, and detailed fluorescence in situ hybridization (FISH) analyses using 23 probes confirmed a 6.7 Mb 6p25-pter deletion. The breakpoint is near a possible 6p25-p24 locus for schizophrenia. Psychotic illness may be part of the neurodevelopmental abnormalities and long-term outcome of patients with 6p terminal deletions. Other similarly affected patients likely remain to be diagnosed in adult populations of schizophrenia and/or mental retardation.

Reviewing the use of antipsychotic drugs in people with intellectual disability

INTRODUCTION

Antipsychotics are the most widely prescribed drugs in people with intellectual disability even if schizophrenia and other psychotic disorders do not affect more than 3% of such population. Many authors outline the lack of studies on the efficacy of antipsychotics on schizophrenia or other psychotic disorders in people with intellectual disability.

MATERIALS AND METHODS

The aim of the present study is to review all evidences resulting from international trials selected by Medline, and compare efficacy and side effects of different antipsychotics in people with both intellectual disability and psychotic disorders and/or behavioural disorders.

RESULTS

195 studies were identified; 117 concern traditional antipychotics while 78 new generation ones. If we consider the type of studies, it results that only the 12.8% of all production is represented by meta-analyses, systematic reviews, and randomised and not controlled trials.

CONCLUSIONS

Randomised controlled trials and systematic reviews would be the golden standard for therapeutical studies; unfortunately they are really few in this field. It is anyway significative that all the studies reported focus on the use of antipsychotics in people with intellectual disability presenting behavioural problems. To increase the validity of these studies it is recommendable to proceed only with well-designed studies, possibly double-blind versus placebo or other medications. There is need to define precise inclusion criteria, precise symptomatological or behavioural targets and adaptative ability assessment, using valid and reliable diagnostic instruments.

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.

Schizophrenia-spectrum psychoses in people with and without intellectual disability

BACKGROUND

Although there is an increased risk of schizophrenia-spectrum psychoses (SSP) in people with intellectual disability (ID), there is a paucity of research evidence into clinical presentation of the disorder in comparison with research into SSP in people without ID.

AIMS

The aims of the study were to compare clinical, functional, and social factors in patients with mild ID (ICD-10: F70) and SSP (ICD-10: F20-9) attending a specialist mental health service for people with ID, with a control group of patients without ID but with SSP attending a generic adult mental health (GAMH) outpatient clinic.

METHOD

A total of 106 patients with SSP (53 with ID and 53 from GAMH) were assessed on psychopathological symptoms, functioning scales and quality of life. They were compared using chi-squared and regression analysis where appropriate.

RESULTS

People with ID and SSP appear to be more debilitated by the co-occurring disorder than those with the same disorder but without ID. Increases in observable psychopathology and "negative" schizophrenic symptoms, and decreased functional abilities were observed in the group with ID when compared to the GAMH group. The clinical implications of these findings are discussed.

Elevated rates of schizophrenia in a familial sample with mental illness and intellectual disability

BACKGROUND

It is unknown whether intellectual disability (ID) is more familially related to psychotic mood disorders or schizophrenia. L. S. Penrose's large sample of families with two or more members admitted to psychiatric hospitals provided a unique opportunity to investigate the familial relationship between mild ID, schizophrenia and psychotic affective disorders.

METHOD

There were 183 affected relative pairs comprising probands with mild ID (95 male, 88 female) and their first or second degree relatives with schizophrenia or psychotic affective disorder.

RESULTS

There were nearly twice as many relatives with a diagnosis of schizophrenia (n = 121) as relatives with affective disorders (n = 62) among the intellectually impaired probands. This excess of schizophrenia was statistically significant, even after accounting for the increased risk of hospitalization for schizophrenia (P = 0.005), and was fairly constant across the different relative types. First-degree relatives with either mental illness were more likely to be parents (n = 77) than siblings (n = 51) or children (n = 3), but there was no excess of mother-son pairs.

CONCLUSIONS

These results suggest a stronger familial relationship of ID with schizophrenia than psychotic affective disorder, and lend some support to the neurodevelopmental hypothesis of schizophrenia.

A critique of the Diagnostic Criteria for Psychiatric Disorders for Use with Adults with Learning Disabilities/Mental Retardation (DC-LD) chapter on non-affective psychotic disorders

BACKGROUND

There has been a longstanding interest in the study of psychotic disorders in adults with intellectual disability. The DC-LD chapter for non-affective psychotic disorders provides operationalised criteria for use with this population.

METHODS

A detailed, structured review of the literature was carried out. Relevant papers were reviewed to provide a framework for a critique of the DC-LD criteria.

RESULTS

Most of the research literature focuses on psychotic disorders in adults with mild intellectural disability and suggests that this group experience clinical symptoms similar to those experienced by adults with average abilities. Although the DC-LD criteria for non-affective psychotic disorders are derived from the ICD-10 equivalent categories they are broader than other classification systems, which may affect their reliability, validity and utility.

CONCLUSIONS

At this stage, it is important that the DC-LD criteria are used alongside established systems to gather information about their use for clinical and research purposes.

Mental disorder in adults with intellectual disability. 1: Prevalence of functional psychiatric illness among a community-based population aged between 16 and 64 years

The reported prevalence of psychiatric illness among adults with intellectual disability (ID) varies widely between 10 and 39%; however, many methodological problems exist. The aims of the present study were to establish the prevalence of functional psychiatric illness among adults with ID who live in the community, in order to compare the overall rate and types of psychiatric illness between the population with ID and the general population without ID, and to establish the risk factors associated with psychiatric illness in adults with ID. The study was done in two stages. In the first part, a trained psychiatrist interviewed 101 randomly selected adults with ID and their carers using the Mini Psychiatric Assessment Schedule for adults with Developmental Disability (Mini PAS-ADD) to screen for psychiatric caseness. Out of these 101 adults, 90 had sufficient communicative abilities that made the administration of Mini PAS-ADD possible. A second trained psychiatrist interviewed 19 out of the 20 adults who were diagnosed as psychiatric cases according to the initial Mini PAS-ADD interview. This psychiatrist interviewed patients and their carers in line with the full PAS-ADD interview. The second psychiatrist was blind to the initial diagnoses made according to the Mini PAS-ADD questionnaire. A final psychiatric diagnosis was made according to International Classification of Diseases - 10th Revision (ICD-10) criteria. Some 14.4% (95% confidence interval = 7.4-21.4%) of the cohort had a psychiatric diagnosis according to ICD-10 criteria: 4.4% had schizophrenia, 2.2% depressive disorder, 2.2% generalized anxiety disorder, 4.4% phobic disorder and 1% delusional disorder. The overall rate of functional psychiatric illness (point prevalence) was similar to that found in the general population (16%). However, the rates of schizophrenic illness and phobic disorder were significantly higher in the study cohort compared with those in the general population (0.4% and 1.1%, respectively). Increasing age and the presence of physical disability were significantly associated with the occurrence of psychiatric illness. Out of the 11 remaining adults with severe ID, two (18%) had a diagnosis of a psychiatric illness (one mania and one anxiety disorder) according to the Diagnostic Assessment for the Severely Handicapped (DASH) questionnaire.

Correlations between clinical and historical variables, and cerebral structural variables in people with mild intellectual disability and schizophrenia

The increased prevalence of schizophrenia in the population with mildly intellectual disability (ID) remains unexplained. The present study explores several possibilities by examining historical/clinical findings in relation to structural neuroimaging findings in three groups: (1) comorbid mild ID and schizophrenia; (2) schizophrenia alone; and (3) mild ID alone. Information about clinical and historical variables was obtained from 101 subjects (39 with comorbidity, 34 with schizophrenia and 28 with mild ID), out of whom 68 (23, 25 and 20, respectively) had had a cerebral magnetic resonance imaging (MRI) scan. Although a number of significant correlations exist between clinical variables and structural MRI abnormalities in all three groups, no clearly predictive inter- or between-group differences emerged. More striking was the finding that showed small amygdalo-hippocampal size to be associated with a history of central nervous system injury, especially meningitis. These findings provide support for the view that cognitive impairment and comorbid psychosis can result from a common cause, such as meningitis or obstetric complications, possibly interacting with other factors, such as family history.

Pharmacotherapy of disorders in mental retardation

This is a review of pharmacotherapy in children and adolescents with mental retardation from the perspective of DSM and ICD disorders. The existing research is reviewed in young people with mental retardation but, when data are lacking, we examined the literature from adults with mental retardation and from typically-developing children. The literature is discussed for each of the following disorders: ADHD, anxiety disorders, bipolar disorder, conduct disorder, depression, enuresis, schizophrenia, self injury, and tics and movement disorders. With the possible exception of ADHD, there is a woeful lack of empirical data on most of these disorders in young people with mental retardation. Clinicians will often be forced to extrapolate from data on adults having mental retardation and from typically-developing children. The best policy is probably to treat such patients cautiously, while gathering data on the effects of such therapy in the hopes of beginning a data base.

Predictors of admission to a high-security hospital of people with intellectual disability with and without schizophrenia

Admission to secure hospital facilities is a rare outcome for people with intellectual disability with or without concomitant psychosis. The present study compares people with mild intellectual disability with and without schizophrenia resident in the Scottish and Northern Irish State Hospital, Carstairs, to matched mild intellectual disability controls, also with and without schizophrenia, in the community. It is hoped that this study may identify socio-demographic, clinical or historical predictors which may lead to admission to secure hospital facilities for people with mild intellectual disability. One hundred and eight subjects were identified from two previous studies which concerned State Hospital patients and patients with intellectual disability with and without schizophrenia. Four experimental groups were derived: (1) 14 individuals with comorbid intellectual disability and schizophrenia who had been resident in the State Hospital; (2) 34 comorbid community control subjects; (3) 33 individuals with intellectual disability and no psychosis who had been resident in the State Hospital; and (4) 27 community control subjects with mild intellectual disability. The four groups were compared on a range of socio-demographic, historical and clinical variables obtained from case records and subject interviews. Relative to community controls, people with intellectual disability and no psychosis in the State Hospital are likely to be single, to have a later age of first psychiatric hospital admission, and to have a history of previous suicide attempts, alcohol abuse or drug misuse. Subjects with comorbid intellectual disability and schizophrenia in the State Hospital are more likely to be male, to have an early age of first psychiatric admission, and to have no family history of either schizophrenia or intellectual disability. Strategies aimed at addressing suicidal behaviour, alcohol and drug misuse amongst people with intellectual disability may facilitate a reduction in the number of admissions to high-security hospitals in the UK. In people with comorbid intellectual disability and schizophrenia, males with an early age of onset and no known family history are more likely to require care and treatment in a secure psychiatric setting. Such comorbid subjects may be suffering from a particular malignant form of schizophrenia, manifesting in childhood as cognitive impairment prior to the early onset of psychosis in teenage years.

Neuroanatomy of comorbid schizophrenia and learning disability: a controlled study

BACKGROUND

Reasons for the higher frequency of schizophrenia in learning-disabled populations are uncertain. We investigated the neuroanatomical basis for this phenomenon by structural magnetic resonance imaging (MRI) in patients with learning disability and schizophrenia, learning-disabled patients, and patients with schizophrenia.

METHODS

Age-matched and sex-matched patients with learning disability (20 cases), schizophrenia (25), and both disorders (23) underwent MRI scans of the brain. Whole brain areas and specific regions of interest were examined. 29 normal controls were also scanned.

FINDINGS

The scans of the group with both disorders were closely similar to those of the schizophrenic group, in terms of both general structures and the structure of the amygdala-hippocampus. However, the amygdala-hippocampus was significantly smaller on both sides than that of normal controls (left 4.1 vs 4.5 cm3, p=0.011; right 4.2 vs 4.99 cm3, p<0.0001). The brains of learning-disabled patients were generally smaller than those of the other three groups, but the amygdalohippocampal complexes were larger.

INTERPRETATION

In terms of brain structure, patients with comorbid learning disability and schizophrenia resemble patients with schizophrenia and not those with learning disability. We suggest that the higher frequency of schizophrenia in learning-disabled patients is due to a greater tendency of schizophrenic patients to develop cognitive deficits, and that within the learning-disabled population there may be individuals whose deficits result from undiagnosed schizophrenia.