Schizophrenia spectrum disorders in people with intellectual disabilities

Copy number variation at the 22q11.2 locus influences prevalence, severity, and psychiatric impact of sleep disturbance

BACKGROUND

Sleep disturbance is common, impairing, and may affect symptomatology in developmental neuropsychiatric disorders. Here, we take a genetics-first approach to study the complex role of sleep in psychopathology. Specifically, we examine severity of sleep disturbance in individuals with a reciprocal copy number variant (CNV) at the 22q11.2 locus and determine sleep's effect on psychiatric symptoms. CNVs (deletion or duplication) at this locus confer some of the greatest known risks of neuropsychiatric disorders; recent studies suggest the 22q11.2 deletion negatively impacts sleep, but sleep disruption associated with 22q11.2 duplication has not been investigated.

METHODS

We compared subjective sleep disturbance and its relationship to psychiatric symptoms cross-sectionally and longitudinally over 1 year in 107 22q11.2 deletion (22qDel) carriers (14.56±8.0 years; 50% male), 42 22q11.2 duplication (22qDup) carriers (16.26±13.1 years; 54.8% male), and 88 age- and sex-matched controls (14.65±7.4 years; 47.1% male). Linear mixed models were used to compare sleep disturbance, assessed via the Structured Interview for Psychosis-Risk Syndromes (SIPS), across groups. Next, CNV carriers were categorized as good or poor sleepers to investigate sleep effects on multiple neurobehavioral traits: psychosis-risk symptoms (SIPS), autism-related behaviors (Repetitive Behavior Scale (RBS) and Social Responsiveness Scale (SRS)), real-world executive function (Behavior Rating Inventory of Executive Function (BRIEF)), and emotional/behavioral problems (Child Behavior Checklist (CBCL)). Linear mixed models tested the effect of sleep category and a group-by-sleep interaction on each measure, cross-sectionally and longitudinally.

RESULTS

22qDel and 22qDup carriers both reported poorer sleep than controls, but did not differ from each other. Cross-sectionally and longitudinally, poor sleepers scored higher on positive symptoms, anxious/depressed, somatic complaints, thought problems, and aggressive behavior, as well as RBS and SRS total scores. There were significant group-by-sleep interactions for positive symptoms and the majority of CBCL subdomains, in which the difference between good and poor sleepers was larger in 22qDel compared to 22qDup.

CONCLUSIONS

Our findings indicate that CNVs at the 22q11.2 locus impact sleep which, in turn, influences psychopathology. Sleep disturbances can differentially impact psychopathology, depending on 22q11.2 gene dosage. Our findings serve as a starting point for exploring a genetic basis for sleep disturbance in developmental neuropsychiatric disorders.

Neurocognitive profile in psychotic versus nonpsychotic individuals with 22q11.2 deletion syndrome

The 22q11.2 deletion syndrome (22q11DS) is associated with increased rates of psychotic disorders and cognitive deficits, but large scale studies are needed to elucidate their interaction. The objective of this two-center study was to identify the neurocognitive phenotype of individuals with 22q11DS and psychotic disorders. We hypothesized that psychotic 22q11DS individuals compared to nonpsychotic deleted individuals would have more severe neurocognitive deficits, especially in executive function and social cognition. These deficits would be present when compared to IQ- matched individuals with Williams Syndrome (WS). Three groups were ascertained from the Tel Aviv and Philadelphia centers: 22q11DS individuals with a psychotic disorder (n=31), nonpsychotic 22q11DS (n=86) and typically-developing controls (TD, n=828). In Tel Aviv a group of individuals with WS (n=18) matched in IQ to the 22q11DS psychotic group was also included. The Penn Computerized Neurocognitive Battery (CNB) was used to assess a wide-range of cognitive functions and all patients underwent structured psychiatric evaluations. 22q11DS individuals performed poorly on all CNB domains compared to TD. Participants with 22q11DS and psychosis, compared to nonpsychotic 22q11DS, had more severe deficits in global neurocognitive performance (GNP), executive function, social cognition and episodic memory domains. The primary deficits were also significant when comparing the Tel Aviv 22q11DS psychotic group to IQ-matched individuals with WS. In conclusion, 22q11DS individuals with a psychotic disorder have specific neurocognitive deficits that are reliably identified cross nationality using the CNB. These cognitive dysfunctions should be further studied as potential endophenotypes of psychosis in 22q11DS and as targets for intervention.

Intellectual developmental disorder in adult psychiatry: A 24-year register study

BACKGROUND

Intellectual developmental disorder (IDD) may pre-dispose for mental health disorders. It is sometimes debated whether the needs of this group are adequately met in general psychiatry. However, little is known about patients with IDD in the psychiatric clinical setting-occurrence, clinical diagnoses, or service use.

AIMS

This study aimed to assess the number of adult patients diagnosed with IDD in a psychiatric clinic, their psychiatric diagnoses, and their use of psychiatric services.

METHODS

Individuals with registered IDD diagnoses were identified in a university hospital adult psychiatric clinic register comprising 67 384 patients.

RESULTS

IDD had been diagnosed in 0.6% of the patients. Psychotic disorders were the most common co-existing psychiatric diagnoses (25.5%). In 21.8% no psychiatric diagnosis other than IDD was registered. More than 50% had been inpatients; 21% had been compulsorily admitted. Patients with IDD had required a mean of five hospital beds per day.

CONCLUSIONS

The percentage, 0.6%, of IDD diagnoses was lower than estimates of the prevalence of IDD in the general population. This may reflect a lower need for psychiatric care, barriers to access services, or diagnostic over-shadowing. One fifth of the patients in this study had no psychiatric diagnosis beside IDD, which may be due to diagnostic difficulties, or other problems (e.g. somatic or behavioural disorders) leading to psychiatric contact. Since patients with IDD use the equivalent of five inpatient beds every year, it is suggested that it may be worthwhile to consider specialized psychiatry with expertise in IDD, even though this group is small.

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.

Risk factors and the evolution of psychosis in 22q11.2 deletion syndrome: a longitudinal 2-site study

OBJECTIVE

22q11.2 Deletion syndrome (22q11.2DS) is associated with high rates of schizophrenia, other neuropsychiatric disorders, and cognitive deficits. The objectives of this 2-center study were to longitudinally assess the trajectories of psychiatric disorders in 22q11.2DS from childhood to adulthood, and to identify risk factors for their emergence.

METHOD

A total of 125 children and adults with 22q11.2DS were evaluated at 2 time points, baseline and follow-up (4 years apart), using standardized psychiatric and cognitive measures.

RESULTS

The rate of mood disorders tended to decrease during childhood and increase during late adolescence. Statistically significant predictors for the presence of a psychotic disorder as well as the severity of positive symptoms at follow-up were identical, and consisted of an anxiety disorder at baseline, lower baseline Full Scale IQ, and a greater decrease in verbal IQ scores between time points. Nine of 10 individuals with an emerging psychotic disorder had an anxiety disorder at baseline. The age of onset for a psychotic disorder was between 14 and 22 years in 82.6% of cases.

CONCLUSIONS

It is important to evaluate the presence of anxiety disorders in children and adolescents with 22q11.2DS, as they are major risk factors for the emergence of psychotic disorders, which usually occur during late adolescence in this at-risk population.

Intellectual disability and other neuropsychiatric outcomes in high-risk children of mothers with schizophrenia, bipolar disorder and unipolar major depression

BACKGROUND

Recent evidence points to partially shared genetics of neuropsychiatric disorders.

AIMS

We examined risk of intellectual disability and other neuropsychiatric outcomes in 3174 children of mothers with schizophrenia, bipolar disorder or unipolar major depression compared with 3129 children of unaffected mothers.

METHOD

We used record linkage across Western Australian population-based registers. The contribution of obstetric factors to risk of intellectual disability was assessed.

RESULTS

Children were at significantly increased risk of intellectual disability with odds ratios (ORs) of 3.2 (95% CI 1.8-5.7), 3.1 (95% CI 1.9-4.9) and 2.9 (95% CI 1.8-4.7) in the maternal schizophrenia, bipolar disorder and unipolar depression groups respectively. Multivariate analysis suggests familial and obstetric factors may contribute independently to the risk. Although summated labour/delivery complications (OR = 1.4, 95% CI 1.0-2.0) just failed to reach significance, neonatal encephalopathy (OR = 7.7, 95% CI 3.0-20.2) and fetal distress (OR = 1.8, 95% CI 1.1-2.7) were independent significant predictors. Rates of rare syndromes in children of mothers with mental disorder were well above population rates. Risk of pervasive developmental disorders, including autism, was significantly elevated for children of mothers with bipolar disorder. Risk of epilepsy was doubled for children of mothers with unipolar depression.

CONCLUSIONS

Our findings provide epidemiological support for clustering of neuropsychiatric disorders. Further larger epidemiological studies are warranted.

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.

Women with and without intellectual disability and psychiatric disorders: an examination of the literature

This article examines the literature on women with and without intellectual disability and psychiatric disorders, using a gender social model of health. Relevant empirical studies, international literature reviews and policies between 1980 and 2007 were identified from electronic databases, journals and secondary sources. Three areas were examined: psychiatric disorders, their contextual background, and their clinical presentation. There are minimal levels of research into women with intellectual disability and psychiatric disorders. However, this article hypothesizes that women with intellectual disability have higher rates of psychiatric disorders than women without. This may result from greater vulnerability related both to internal factors (;intra': cognitive deficits, poorer communication skills, limited social skills) and to the external world (;inter': lack of opportunities, stigma, poor social support networks). The article argues that such women require gender-sensitive mental health services. However, more empirical evidence is required to support this claim and to inform development and delivery of services.

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.