Cognitive and behavioral trajectories in 22q11DS from childhood into adolescence: a prospective 6-year follow-up study

The 22q11.2 Deletion Syndrome from A Biopsychosocial Perspective: A Series of Cases with an ICF-Based Approach

The 22q11.2 deletion syndrome (DS) can have a significant impact on functionality. The purpose was to describe 22q11.2DS children with functioning from a biopsychosocial perspective, focusing on the impact of children's health condition from domains of the International Classification of Functioning, Disability, and Health (ICF).

METHODS

A descriptive, cross-sectional case series study with seven 22q11.2DS children. A questionnaire with an ICF checklist for 22q11.2DS was completed using a structured interview. The Wechsler Abbreviated Scale of Intelligence (WASI) was used to determine the Intelligence Quotient (IQ).

RESULTS

Seven participants from 7 to 12 years old, presented some level of IQ impairment. It was observed that 22q11.2DS children experience significant intellectual, cognitive, and speech impairments across ICF Body Function domains. Impairments related to nose and pharynx were found in only one patient. The most relevant categories considered limitations in the Activity and Participation components pertained to producing nonverbal messages, communication, handling stress, and social interaction. Family, health professionals, and acquaintances were perceived as facilitators in the component Environmental Factors.

CONCLUSION

The sample has its functioning affected by aspects that go beyond impairments in body structure and function. The organization of information from the perspective of the ICF is a different approach that helps clinical reasoning.

Event-related potential (ERP) markers of 22q11.2 deletion syndrome and associated psychosis

22q11.2 deletion syndrome (22q11.2DS) is a multisystemic disorder characterized by a wide range of clinical features, ranging from life-threatening to less severe conditions. One-third of individuals with the deletion live with mild to moderate intellectual disability; approximately 60% meet criteria for at least one psychiatric condition.22q11.2DS has become an important model for several medical, developmental, and psychiatric disorders. We have been particularly interested in understanding the risk for psychosis in this population: Approximately 30% of the individuals with the deletion go on to develop schizophrenia. The characterization of cognitive and neural differences between those individuals who develop schizophrenia and those who do not, despite being at genetic risk, holds important promise in what pertains to the clarification of paths to disease and to the development of tools for early identification and intervention.Here, we review our previous event-related potential (ERP) findings as potential markers for 22q11.2DS and the associated risk for psychosis, while discussing others' work. We focus on auditory processing (auditory-evoked potentials, auditory adaptation, and auditory sensory memory), visual processing (visual-evoked potentials and visual adaptation), and inhibition and error monitoring.The findings discussed suggest basic mechanistic and disease process effects on neural processing in 22q11.2DS that are present in both early sensory and later cognitive processing, with possible implications for phenotype. In early sensory processes, both during auditory and visual processing, two mechanisms that impact neural responses in opposite ways seem to coexist-one related to the deletion, which increases brain responses; another linked to psychosis, decreasing neural activity. Later, higher-order cognitive processes may be equally relevant as markers for psychosis. More specifically, we argue that components related to error monitoring may hold particular promise in the study of risk for schizophrenia in the general population.

Age-Related Improvements in Executive Functions and Focal Attention in 22q11.2 Deletion Syndrome Vary Across Domain and Task

OBJECTIVE

Executive functions (EF) and focal attention have been identified as a weakness in the profile of 22q11.2 deletion syndrome (22q11DS). However, due to a high variety of tasks used across previous studies, it remains unclear whether impairments may be more pronounced for specific subdomains of EF and focal attention. Furthermore, age-related changes have only been examined in a few studies, so far only yielding a partial view of the overall developmental profile.

METHOD

In a broad age range (8-35 years) composed of longitudinal data, 183 participants (103 diagnosed with 22q11DS) completed an extensive assessment of EF and attention. To get a more comprehensive overview of specific versus global impairments, several tasks were assessed within multiple domains.

RESULTS

Results suggest differential impairments and trajectories in specific EF subdomains. Specifically, our findings suggest that individuals with 22q11DS not only showed lower overall inhibition skills, but also that initiation skills developed at a slower pace compared to healthy controls. Results are less clear regarding cognitive flexibility, updating and focal attention, for which performance strongly depended on the tasks that was selected to assess the domain.

CONCLUSIONS

Findings confirm and extend knowledge on differential developmental patterns of EF and attention domains in 22q11DS. They further stress the necessity to administer extensive, multifaceted evaluations to gain a more reliable overview of patients' cognitive profile.

Abnormal nodal and global network organization in resting state functional MRI from subjects with the 22q11 deletion syndrome

The 22q11 deletion syndrome is a genetic disorder associated with a high risk of developing psychosis, and is therefore considered a neurodevelopmental model for studying the pathogenesis of schizophrenia. Studies have shown that localized abnormal functional brain connectivity is present in 22q11 deletion syndrome like in schizophrenia. However, it is less clear whether these abnormal cortical interactions lead to global or regional network disorganization as seen in schizophrenia. We analyzed from a graph-theory perspective fMRI data from 40 22q11 deletion syndrome patients and 67 healthy controls, and reconstructed functional networks from 105 brain regions. Between-group differences were examined by evaluating edge-wise strength and graph theoretical metrics of local (weighted degree, nodal efficiency, nodal local efficiency) and global topological properties (modularity, local and global efficiency). Connectivity strength was globally reduced in patients, driven by a large network comprising 147 reduced connections. The 22q11 deletion syndrome network presented with abnormal local topological properties, with decreased local efficiency and reductions in weighted degree particularly in hub nodes. We found evidence for abnormal integration but intact segregation of the 22q11 deletion syndrome network. Results suggest that 22q11 deletion syndrome patients present with similar aberrant local network organization as seen in schizophrenia, and this network configuration might represent a vulnerability factor to psychosis.

Cognitive deficits in childhood, adolescence and adulthood in 22q11.2 deletion syndrome and association with psychopathology

22q11.2 Deletion Syndrome (22q11.2DS) is associated with high risk of psychiatric disorders and cognitive impairment. It remains unclear to what extent key cognitive skills are associated with psychopathology, and whether cognition is stable over time in 22q11.2DS. 236 children, adolescents and adults with 22q11.2DS and 106 typically developing controls were recruited from three sites across Europe. Measures of IQ, processing speed, sustained attention, spatial working memory and psychiatric assessments were completed. Cognitive performance in individuals was calculated relative to controls in different age groups (children (6-9 years), adolescents (10-17 years), adults (18+ years)). Individuals with 22q11.2DS exhibited cognitive impairment and higher rates of psychiatric disorders compared to typically developing controls. Presence of Autism Spectrum Disorder symptoms was associated with greater deficits in processing speed, sustained attention and working memory in adolescents but not children. Attention deficit hyperactivity disorder in children and adolescents and psychotic disorder in adulthood was associated with sustained attention impairment. Processing speed and working memory were more impaired in children and adults with 22q11.2DS respectively, whereas the deficit in sustained attention was present from childhood and remained static over developmental stages. Psychopathology was associated with cognitive profile of individuals with 22q11.2DS in an age-specific and domain-specific manner. Furthermore, magnitude of cognitive impairment differed by developmental stage in 22q11.2DS and the pattern differed by domain.

The emergence of psychotic experiences in the early adolescence of 22q11.2 Deletion Syndrome

Individuals with 22q11.2 Deletion Syndrome (22q11.2DS) are at substantial increased risk of psychosis spectrum outcomes including schizophrenia. We conducted a prospective, longitudinal study of the psychopathological and neurocognitive correlates of early psychotic phenomena in young people with 22q11.2DS (n = 75, mean age time 1 (T1) 9.9 years, time 2 (T2) 12.5 years). We also assessed unaffected control siblings (n = 33, mean age T1 10.6 years, T2 13.4 years). The prevalence of psychotic experiences, defined as subthreshold psychotic phenomena, substantially increased in children with 22q11.2DS from 4% (n = 3) in childhood (T1) to 21% (n = 16) in early adolescence (T2) (p = 0.001), and at T2 prevalence was significantly elevated (p = 0.020) relative to control siblings (3%). The emergence of psychotic experiences was associated with levels of childhood anxiety symptoms at T1 and differential development of the attention-executive domain. IQ ability and IQ change, however, were not associated with the emergence of psychotic experiences, indicating that initial changes in attention-executive functioning may precede the decline in global cognition that has been reported to be associated with later stages of psychosis development. Our study highlights that psychotic phenomena emerge early in 22q11.2DS and we implicate attention-executive functioning and anxiety as key domains associated with the development of these psychotic experiences.

Intellectual performance profi le of a sample of children and adolescents from Brazil with 22q11.2 Deletion Syndrome (22q11.2DS) based on the Wechsler Scale

Abstract The 22q11.2 Deletion Syndrome (22q11.2DS), the most common human chromosome microdeletion syndrome, is associated with a very heterogeneous neurocognitive phenotype. One of the main characteristics of the syndrome spectrum is the intellectual variability, which encompasses average performance and intellectual disability and discrepancies between Verbal Intelligence Quotient and Performance Verbal Intelligence Quotient, with greater impairment in nonverbal tasks. The present study aimed at investigating the intellectual performance aspects of a 21children and adolescents sample from Brazil who had been diagnosed with 22q11.2DS, based on the Wechsler Intelligence Scale for Children - 4th edition. The samples were reviewed considering the differences between indices. The results revealed an Full Scale Intelligence Quotient predominant in the borderline range (42 to 104) and a significant discrepancy between the indices of Verbal Comprehension and Perceptual Reasoning in 42% of the sample. With regard to the performance in the subtests alone, a better performance was found in Similarities, whereas block design, matrix reasoning, digit span and letter-number sequencing subtests were the most challenging. These findings indicate that a comprehensive assessment of intellectual performance aspects covering the different measures of the Wechsler Intelligence Scale may contribute to a broader understanding of the neurocognitive phenotype associated with 22q11.2DS.

Education and employment trajectories from childhood to adulthood in individuals with 22q11.2 deletion syndrome

22q11.2 deletion syndrome (22q11.2DS) is the most common known microdeletion in humans occurring in 1 out of 2000-4000 live births, with increasing numbers of individuals with the microdeletion living into adulthood. The aim of the study was to explore the education and employment trajectories of individuals with 22q11.2DS from childhood to adulthood in a large cohort composed of two significant samples. 260 individuals with 22q11.2DS, 134 male and 126 female, aged 5-59 years (mean age 21.3 ± 10.8 years) were evaluated at two sites, Geneva (GVA) and Tel Aviv (TA). Psychiatric comorbidities, IQ score, and adaptive functioning were assessed using gold-standard diagnostic tools. Demographic factors, such as data about education, employment, marital status, and living status, were collected. Children entering elementary school (5-12 years) were significantly more likely to attend a mainstream school, while adolescents were significantly more likely to attend special education schools (p < 0.005). Cognitive abilities, and not adaptive functioning, predicted school placement. Among adults with 22q11.2DS (n = 138), 57 (41.3%) were unemployed, 46 (33.3%) were employed in open market employment, and 35 (25.4%) worked in assisted employment. In adulthood, adaptive functioning more than cognitive abilities predicted employment. Surprisingly, psychotic spectrum disorders were not found to be associated with employment. Individuals with 22q11.2DS are characterized by heterogeneity in educational and employment profiles. We found that cognitive abilities and adaptive functioning, and not the presence of psychiatric disorders, are key factors in school placement and employment. These factors should, therefore, be taken into account when planning optimal development of individuals with 22q11.2DS.

Exploratory study on cognitive abilities and social responsiveness in children with 22q11.2 deletion syndrome (22q11DS) and children with idiopathic intellectual disability (IID)

BACKGROUND

Development of cognitive skills and social responsiveness are areas of concern in children with 22q11.2 deletion syndrome (22q11DS). It remains unclear if the cognitive and social profiles and trajectories are syndrome-specific or similar to those of children with idiopathic intellectual disabilities (IID) with or without comorbid autism spectrum disorder (ASD).

AIMS AND METHODS

In this exploratory study, we examined and compared five broad cognitive abilities (BCAs) and the social responsiveness in primary school-aged children with 22q11DS (age 6-13, n = 21) and IQ-matched peers with IID (n = 21). The relative strengths and weaknesses of both groups were re-evaluated after 19 to 30 months.

OUTCOMES AND RESULTS

Four different cognitive trajectories (i.e. absolute progress, stability, growing into deficit, and absolute decline) were demonstrated in both groups. Most children showed combined types of trajectories across BCAs resulting in a complex changing cognitive profile. In the 22q11DS group, social responsiveness problems increased, whereas no significant change was observed in the IID group.

CONCLUSIONS AND IMPLICATIONS

Results reflect similar cognitive and social responsiveness profiles and trajectories across groups with children with 22q11DS being more at risk for growing into a social deficit. We recommend repeated monitoring of social skills development to adapt the environmental demands to the child's individual social capacities.

Development of Structural Covariance From Childhood to Adolescence: A Longitudinal Study in 22q11.2DS

Background: Schizophrenia is currently considered a neurodevelopmental disorder of connectivity. Still few studies have investigated how brain networks develop in children and adolescents who are at risk for developing psychosis. 22q11.2 Deletion Syndrome (22q11DS) offers a unique opportunity to investigate the pathogenesis of schizophrenia from a neurodevelopmental perspective. Structural covariance (SC) is a powerful approach to explore morphometric relations between brain regions that can furthermore detect biomarkers of psychosis, both in 22q11DS and in the general population.

Methods: Here we implement a state-of-the-art sliding-window approach to characterize maturation of SC network architecture in a large longitudinal cohort of patients with 22q11DS (110 with 221 visits) and healthy controls (117 with 211 visits). We furthermore propose a new clustering-based approach to group regions according to trajectories of structural connectivity maturation. We correlate measures of SC with development of working memory, a core executive function that is highly affected in both idiopathic psychosis and 22q11DS. Finally, in 22q11DS we explore correlations between SC dysconnectivity and severity of internalizing psychopathology.

Results: In HCs network architecture underwent a quadratic developmental trajectory maturing up to mid-adolescence. Late-childhood maturation was particularly evident for fronto-parietal cortices, while Default-Mode-Network-related regions showed a more protracted linear development. Working memory performance was positively correlated with network segregation and fronto-parietal connectivity. In 22q11DS, we demonstrate aberrant maturation of SC with disturbed architecture selectively emerging during adolescence and correlating more severe internalizing psychopathology. Patients also presented a lack of typical network development during late-childhood, that was particularly prominent for frontal connectivity.

Conclusions: Our results suggest that SC maturation may underlie critical cognitive development occurring during late-childhood in healthy controls. Aberrant trajectories of SC maturation may reflect core developmental features of 22q11DS, including disturbed cognitive maturation during childhood and predisposition to internalizing psychopathology and psychosis during adolescence.

Early adolescent outcomes of joint developmental trajectories of problem behavior and IQ in childhood

General cognitive ability (IQ) and problem behavior (externalizing and internalizing problems) are variable and inter-related in children. However, it is unknown how they co-develop in the general child population and how their patterns of co-development may be related to later outcomes. We carried out this study to explore this. Using data from 16,844 Millennium Cohort Study children, we fitted three-parallel-process growth mixture models to identify joint developmental trajectories of internalizing, externalizing and IQ scores at ages 3-11 years. We then examined their associations with age 11 outcomes. We identified a typically developing group (83%) and three atypical groups, all with worse behavior and ability: children with improving behavior and low (but improving in males) ability (6%); children with persistently high levels of problems and low ability (5%); and children with worsening behavior and low ability (6%). Compared to typically developing children, the latter two groups were more likely to show poor decision-making, be bullies or bully victims, engage in antisocial behaviors, skip and dislike school, be unhappy and have low self-esteem. By contrast, children (especially males) in the improver group had outcomes that were similar to, or even better than, those of their typically developing peers. These findings encourage the development of interventions to target children with both cognitive and behavioral difficulties.

A neurogenetic model for the study of schizophrenia spectrum disorders: the International 22q11.2 Deletion Syndrome Brain Behavior Consortium

Rare copy number variants contribute significantly to the risk for schizophrenia, with the 22q11.2 locus consistently implicated. Individuals with the 22q11.2 deletion syndrome (22q11DS) have an estimated 25-fold increased risk for schizophrenia spectrum disorders, compared to individuals in the general population. The International 22q11DS Brain Behavior Consortium is examining this highly informative neurogenetic syndrome phenotypically and genomically. Here we detail the procedures of the effort to characterize the neuropsychiatric and neurobehavioral phenotypes associated with 22q11DS, focusing on schizophrenia and subthreshold expression of psychosis. The genomic approach includes a combination of whole-genome sequencing and genome-wide microarray technologies, allowing the investigation of all possible DNA variation and gene pathways influencing the schizophrenia-relevant phenotypic expression. A phenotypically rich data set provides a psychiatrically well-characterized sample of unprecedented size (n=1616) that informs the neurobehavioral developmental course of 22q11DS. This combined set of phenotypic and genomic data will enable hypothesis testing to elucidate the mechanisms underlying the pathogenesis of schizophrenia spectrum disorders.

Childhood cognitive development in 22q11.2 deletion syndrome: case-control study

Background22q11.2 deletion syndrome (22q11.2DS) is associated with a high risk of childhood as well as adult psychiatric disorders, in particular schizophrenia. Childhood cognitive deterioration in 22q11.2DS has previously been reported, but only in studies lacking a control sample.AimsTo compare cognitive trajectories in children with 22q11.2DS and unaffected control siblings.MethodA longitudinal study of neurocognitive functioning (IQ, executive function, processing speed and attention) was conducted in children with 22q11.2DS (n = 75, mean age time 1 (T₁) 9.9, time 2 (T₂) 12.5) and control siblings (n = 33, mean age T₁ 10.6, T₂ 13.4).ResultsChildren with 22q11.2DS exhibited deficits in all cognitive domains. However, mean scores did not indicate deterioration. When individual trajectories were examined, some participants showed significant decline over time, but the prevalence was similar for 22q11.2DS and control siblings. Findings are more likely to reflect normal developmental fluctuation than a 22q11.2DS-specific abnormality.ConclusionsChildhood cognitive deterioration is not associated with 22q11.2DS. Contrary to previous suggestions, we believe it is premature to recommend repeated monitoring of cognitive function for identifying individual children with 22q11.2DS at high risk of developing schizophrenia.

Social cognitive impairment in 22q11 deletion syndrome: A review

Individuals with 22q11.2 deletion syndrome (22q11DS) exhibit a broad array of physical and psychiatric features, of which impaired social cognition and poor social functioning are common. This review seeks to (1) characterize the current understanding of impairment across social cognitive domains in the context of 22q11DS, and (2) synthesize the relevant literature on social cognition and psychosis, given that the prevalence of psychosis in 22q11DS is especially high compared to the general population. A total of 16 papers examining social cognition in 22q11DS were identified through a comprehensive literature search conducted using electronic databases such as PubMed and PSYCInfo. Results suggest that individuals with 22q11DS exhibit impaired emotion processing and complex theory of mind relative to their typically developing peers, though some findings were accounted for by neurocognitive and intellectual abilities. Further, no studies have examined the domains of attribution bias or social perception in 22q11DS, highlighting a critical gap in the extant literature. More research is needed to better elucidate the trajectory of how and why social cognitive impairment develops in 22q11DS, and to explore possible relationships to psychiatric comorbidities like psychosis. Treatment implications and future steps are considered.

Explaining the variable penetrance of CNVs: Parental intelligence modulates expression of intellectual impairment caused by the 22q11.2 deletion

The role of rare genetic variants, in particular copy number variants (CNVs), in the etiology of neurodevelopmental disorders is becoming increasingly clear. While the list of these disorder-related CNVs continues to lengthen, it has also become clear that in nearly all genetic variants the proportion of carriers who express the associated phenotype is far from 100%. To understand this variable penetrance of CNVs it is important to realize that even the largest CNVs represent only a tiny fraction of the entire genome. Therefore, part of the mechanism underlying the variable penetrance of CNVs is likely the modulatory impact of the rest of the genome. In the present study we used the 22q11DS as a model to examine whether the observed penetrance of intellectual impairment-one of the main phenotypes associated with 22q11DS-is modulated by the intellectual level of their parents, for which we used the parents' highest level of education as a proxy. Our results, based on data observed in 171 children with 22q11DS in the age range of 5-15 years, showed a significant association between estimated parental cognitive level and intelligence in offspring (full scale, verbal and performance IQ), with the largest effect size for verbal IQ. These results suggest that possible mechanisms involved in the variable penetrance observed in CNVs include the impact of genetic background and/or environmental influences. © 2016 Wiley Periodicals, Inc.

Developmental trajectories in 22q11.2 deletion

Chromosome 22q11.2 deletion syndrome (22q11.2DS), a neurogenetic condition, is the most common microdeletion syndrome affecting 1 in 2,000-4,000 live births and involving haploinsufficiency of ∼50 genes resulting in a multisystem disorder. Phenotypic expression is highly variable and ranges from severe life-threatening conditions to only a few associated features. Most common medical problems include: congenital heart disease, in particular conotruncal anomalies; palatal abnormalities, most frequently velopharyngeal incompetence (VPI); immunodeficiency; hypocalcemia due to hypoparathyroidism; genitourinary anomalies; severe feeding/gastrointestinal differences; and subtle dysmorphic facial features. The neurocognitive profile is also highly variable, both between individuals and during the course of development. From infancy onward, motor delays (often with hypotonia) and speech/language deficits are commonly observed. During the preschool and primary school ages, learning difficulties are very common. The majority of patients with 22q11.2DS have an intellectual level that falls in the borderline range (IQ 70-84), and about one-third have mild to moderate intellectual disability. More severe levels of intellectual disability are uncommon in children and adolescents but are more frequent in adults. Individuals with 22q11.2DS are at an increased risk for developing several psychiatric disorders including attention deficit with hyperactivity disorder (ADHD), autism spectrum disorder (ASD), anxiety and mood disorders, and psychotic disorders and schizophrenia. In this review, we will focus on the developmental phenotypic transitions regarding cognitive development in 22q11.2DS from early preschool to adulthood, and on the changing behavioral/psychiatric phenotype across age, on a background of frequently complex medical conditions.

Cognitive decline preceding the onset of psychosis in patients with 22q11.2 deletion syndrome

IMPORTANCE

Patients with 22q11.2 deletion syndrome (22q11DS) have an elevated (25%) risk of developing schizophrenia. Recent reports have suggested that a subgroup of children with 22q11DS display a substantial decline in cognitive abilities starting at a young age.

OBJECTIVE

To determine whether early cognitive decline is associated with risk of psychotic disorder in 22q11DS.

DESIGN, SETTING, AND PARTICIPANTS

Prospective longitudinal cohort study. As part of an international research consortium initiative, we used the largest data set of intelligence (IQ) measurements in patients with 22q11DS reported to date to investigate longitudinal IQ trajectories and the risk of subsequent psychotic illness. A total of 829 patients with a confirmed hemizygous 22q11.2 deletion, recruited through 12 international clinical research sites, were included. Both psychiatric assessments and longitudinal IQ measurements were available for a subset of 411 patients (388 with ≥1 assessment at age 8-24 years).

MAIN OUTCOMES AND MEASURES

Diagnosis of a psychotic disorder, initial IQ, longitudinal IQ trajectory, and timing of the last psychiatric assessment with respect to the last IQ test.

RESULTS

Among 411 patients with 22q11DS, 55 (13.4%) were diagnosed as having a psychotic disorder. The mean (SD) age at the most recent psychiatric assessment was 16.1 (6.2) years. The mean (SD) full-scale IQ at first cognitive assessment was lower in patients who developed a psychotic disorder (65.5 [12.0]) compared with those without a psychotic disorder (74.0 [14.0]). On average, children with 22q11DS showed a mild decline in IQ (full-scale IQ, 7.04 points) with increasing age, particularly in the domain of verbal IQ (9.02 points). In those who developed psychotic illness, this decline was significantly steeper (P < .001). Those with a negative deviation from the average cognitive trajectory observed in 22q11DS were at significantly increased risk for the development of a psychotic disorder (odds ratio = 2.49; 95% CI, 1.24-5.00; P = .01). The divergence of verbal IQ trajectories between those who subsequently developed a psychotic disorder and those who did not was distinguishable from age 11 years onward.

CONCLUSIONS AND RELEVANCE

In 22q11DS, early cognitive decline is a robust indicator of the risk of developing a psychotic illness. These findings mirror those observed in idiopathic schizophrenia. The results provide further support for investigations of 22q11DS as a genetic model for elucidating neurobiological mechanisms underlying the development of psychosis.

Glutamatergic markers, age, intellectual functioning and psychosis in 22q11 deletion syndrome

RATIONALE

Patients with 22q11 deletion syndrome (22q11DS) have a high prevalence of intellectual disabilities and psychiatric disorders, including psychosis. Haplo-insufficiency of genes in the deleted region may offer a partial explanation for the increased vulnerability for psychosis and intellectual disability. One gene of particular interest is the gene coding for proline dehydrogenase (PRODH), an enzyme responsible for the conversion of proline into glutamate.

OBJECTIVES

Because abnormalities in glutamatergic signaling are thought to be responsible for cognition and psychosis in the general population, we hypothesized that PRODH haplo-insufficiency may underlie some of the cognitive and psychotic features seen in 22q11DS.

METHODS

In this explorative study, we investigated the relation between plasma proline, glutamate, and glutamine and age, intelligence, and psychosis in 64 adults with 22q11DS.

RESULTS

Hyperprolinemia was found in 31.3% of subjects with 22q11DS. A relation between glutamine, glutamate, proline, and presence of psychosis was not observed. Regression analysis revealed a positive relation between plasma glutamate and age, a positive relation of glutamate with antipsychotic drugs, a relation of glutamine and gender, and a positive relation of glutamine and mood stabilizing drugs, and a negative relation of the ratio glutamine/glutamate and age. The group with relatively lower IQ had higher glutamate levels compared to the group with relatively higher IQ.

CONCLUSIONS

Our results suggest that 22q11DS is accompanied by abnormalities in glutamatergic metabolism. Future longitudinal studies are needed to further investigate the glutamatergic system in 22q11DS and how this affects the development of cognitive problems and psychopathology.