Self-injurious behaviour in intellectual disability syndromes: evidence for aberrant pain signalling as a contributing factor

An investigation of sleep problems, gastrointestinal symptoms, comorbid psychopathology and challenging behavior in children and adolescents with Down Syndrome

BACKGROUND

Down syndrome (DS) is one of the most common chromosomal abnormalities, and children with DS have increased risks of receiving diagnoses of specific comorbidities.

AIMS

This study aimed to assess the frequencies and relationships between sleep problems, gastrointestinal (GI) symptoms, comorbid psychopathology, and challenging behavior.

METHODS AND PROCEDURES

The Children's Sleep Habits Questionnaire, Gastrointestinal Symptom Inventory, Autism Spectrum Disorder-Comorbid for Children, and Behavior Problems Inventory-Short Form were completed by 123 parents of children and adolescents with DS.

OUTCOMES AND RESULTS

The frequency of GI symptoms was 74.8 %, with high frequencies also found for: sleep problems (100 %), challenging behavior (100 %), and moderate to severe levels of comorbid psychopathology (tantrum=80 %; repetitive behavior=63 %; avoidant behavior=82 %; worry/depressed=61 %; conduct behavior=100 %; over-eating=100 %; under-eating=100 %). A significant moderate correlation was found between total GI symptoms and self-injurious behavior frequency. Children who presented with abdominal pain engaged in self-injurious behavior more frequently than those with no abdominal pain.

CONCLUSIONS AND IMPLICATIONS

Findings indicated a high frequency of sleep problems, comorbid psychopathology, GI symptoms, and challenging behavior and demonstrated a relationship between GI symptoms and self-injurious behavior in children and adolescents with DS. This research illustrated the importance of investigating comorbid conditions in individuals with DS. WHAT THIS PAPER ADDS?: Down Syndrome (DS) is a genetic condition characterized by trisomy 21 and is a leading cause of intellectual disability worldwide. The prevalence of DS is commonly associated with advanced maternal age and is associated with multiple comorbid conditions. The current study aimed to investigate the frequency of and relationship between sleep problems, gastrointestinal symptoms, comorbid psychopathology, and challenging behavior in children and adolescents with DS. High-frequency levels were found for sleep problems (100 %), challenging behavior (100 %), gastrointestinal symptoms (74.8 %), and moderate to severe levels of the different comorbid psychopathologies (tantrum=80 %; repetitive behavior=63 %; avoidant behavior=82 %; worry/depressed=61 %; conduct behavior=100 %; over-eating=100 %; under-eating=100 %). Results indicated a significant difference in self-injurious behavior frequency between individuals who presented with abdominal pain and those who did not. This study is the first to investigate the relationship of multiple comorbid conditions in a sample of children with DS. This paper adds to the literature by demonstrating the frequency of a number of comorbid conditions in children and adolescents with DS. The paper also adds novel findings to the literature by investigating the relationships between comorbid conditions in this population. The findings of this paper highlighted the frequency and comorbidities that exist between gastrointestinal symptoms, sleep problems, comorbid psychopathology, and challenging behavior. Analyses indicated that those who presented with abdominal pain, engaged in self-injurious behavior more frequently. Sleep problems, gastrointestinal symptoms, comorbid psychopathology, and challenging behavior in children and adolescents with Down Syndrome.

A review of the use of psychotropic medication to address challenging behaviour in neurodevelopmental disorders

Engagement in challenging behaviour (e.g., aggression, self-injury) is reported to occur in neurodevelopmental disorders such as intellectual disabilities (ID), autism spectrum disorder (ASD), and fragile X syndrome (FXS). Common interventions to address these behaviours include both behavioural and pharmacological approaches. Although psychotropic medications are commonly used to address challenging behaviour in ID, ASD, and FXS, demonstration of the effectiveness of treatment is limited. Furthermore, research examining interaction effects between psychotropic medication, challenging behaviour, and environmental events within specific neurodevelopmental disorders such as ID, ASD, and FXS is scarce. The purpose of this chapter is to provide an overview of challenging behaviour within ID, ASD, and FXS and of the effectiveness of psychotropic medication as an intervention for challenging behaviour within these neurodevelopmental disorders. Finally, research examining how psychotropic medication may impact the relationship between challenging behaviour and environmental events is reviewed.

The recognition, assessment and perceptions of total pain in people with profound intellectual disabilities: A mixed methods systematic review

BACKGROUND

People with profound intellectual disabilities are a population with complex comorbidities. Total pain recognises the interconnectedness of aspects of pain; social, psychological, physical, emotional, spiritual. Pain is under-recognised due to communication challenges and carers perceptions. This review's purpose is to synthesise current literature and provide guidance for future research and care.

METHODS

Five databases were searched in this mixed methods systematic review (Cinahl, Medline, Psycinfo, Web of Science, Scopus). Articles retrieved were reported via a PRISMA flow diagram. Quality appraisal utilised the mixed methods appraisal tool (MMAT). A convergent qualitative design was the method of data synthesis.

RESULTS

Data from 16 included articles generated four themes; Absent voices, reductionist assessment, pain intensity, valuing expertise. Data included physical pain only.

CONCLUSION

Multifaceted pain needs inclusion in research. Assessment must consider the unique expressions of pain by individuals with profound intellectual disabilities. A sharing of expertise may improve pain care.

Pain Management in the Most Vulnerable Intellectual Disability: A Review

This review is made up of two parts; the first part discussing intellectual disability (ID) in general, while the second part covers the pain associated with intellectual disability and the challenges and practical tips for the management of pain associated with (ID). Intellectual disability is characterized by deficits in general mental abilities, such as reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience. ID is a disorder with no definite cause but has multiple risk factors, including genetic, medical, and acquired. Vulnerable populations such as individuals with intellectual disability may experience more pain than the general population due to additional comorbidities and secondary conditions, or at least the same frequency of pain as in the general population. Pain in patients with ID remains largely unrecognized and untreated due to barriers to verbal and non-verbal communication. It is important to identify patients at risk to promptly prevent or minimize those risk factors. As pain is multifactorial, thus, a multimodal approach using both pharmacotherapy and non-pharmacological management is often the most beneficial. Parents and caregivers should be oriented to this disorder, given adequate training and education, and be actively involved with the treatment program. Significant work to create new pain assessment tools to improve pain practices for individuals with ID has taken place, including neuroimaging and electrophysiological studies. Recent advances in technology-based interventions such as virtual reality and artificial intelligence are rapidly growing to help give patients with ID promising results to develop pain coping skills with effective reduction of pain and anxiety. Therefore, this narrative review highlights the different aspects regarding the current status of the pain associated with intellectual disability, with more emphasis on the recent pieces of evidence for the assessment and management of pain among populations with intellectual disability.

Botulinum Neurotoxin Injections in Children with Self-Injurious Behaviors

Self-injurious behaviors are repetitive, persistent actions directed toward one's body that threaten or cause physical harm. These behaviors are seen within a broad spectrum of neurodevelopmental and neuropsychiatric conditions, often associated with intellectual disability. Injuries can be severe and distressing to patients and caregivers. Furthermore, injuries can be life-threatening. Often, these behaviors are challenging to treat and require a tiered, multimodal approach which may include mechanical/physical restraints, behavioral therapy, pharmacotherapy, or in some cases, surgical management, such as tooth extraction or deep brain stimulation. Here, we describe a series of 17 children who presented to our institution with self-injurious behaviors in whom botulinum neurotoxin injections were found helpful in preventing or lessening self-injury.

Reliable assessment of pain behaviour in adults with profound intellectual and multiple disabilities: The development of an instruction protocol

BACKGROUND

Persons with profound intellectual and multiple disabilities (PIMD) are vulnerable when it comes to experiencing pain. Reliable assessment of pain-related behaviour in these persons is difficult. Aim To determine how pain items can be reliably scored in adults with PIMD.

METHODS

We developed an instruction protocol for the assessment of pain-related behaviour in four phases. We used videos of 57 adults with PIMD during potentially painful situations. The items were assessed for inter-rater reliability (Cohen's kappa or percentage of agreement).

RESULTS

The developed instruction protocol appeared to be adequate. Twelve items had satisfactory inter-rater reliability (n = 9: .30-1.00; n = 3: 85%-100%).

DISCUSSION

Calibrating and adjustments to the instructions and item set appeared to be crucial to reliably score 12 items in adults with PIMD. Further research should focus on creating an assessment instrument based on these reliably scored items.

Preliminary Development and Testing of the Risk Assessment Checklist for Self-Injury in Autism-Medical (RACSA-M)

Self-injurious behavior (SIB) is a major treatment focus for clinicians treating children with autism spectrum disorder (ASD). A review of the literature identified medical conditions that may be risk factors for an individual engaging in SIB. This study involved the creation and preliminary validation of a standardized assessment checklist: Risk Assessment Checklist for Self-Injury in Autism-Medical (RASCA-M) for the physical, behavioral, and diagnostic evaluation of non-verbal children with autism and SIB living in a residential setting. Preliminary content validity, criterion-related validity, and interobserver agreement were established. The RACSA-M is a promising instrument to assess underlying medical issues in non-verbal children with ASD and SIB.

Altered nociceptive behavior and emotional contagion of pain in mouse models of autism

Individuals with autism spectrum disorder (ASD) have altered sensory processing but may ineffectively communicate their experiences. Here, we used a battery of nociceptive behavioral tests to assess sensory alterations in two commonly used mouse models of ASD, BTBR T⁺ Itpr3^tf /J (BTBR), and fragile-X mental retardation-1 knockout (Fmr1-KO) mice. We also asked whether emotional contagion, a primitive form of empathy, was altered in BTBR and Fmr1 KO mice when experiencing pain with a social partner. BTBR mice demonstrated mixed nociceptive responses with hyporesponsivity to mechanical/thermal stimuli and intraplantar injections of formalin and capsaicin while displaying hypersensitivity on the acetic acid test. Fmr1-KO mice were hyposensitive to mechanical stimuli and intraplantar injections of capsaicin and formalin. BTBR and Fmr1-KO mice developed significantly less mechanical allodynia following intraplantar injections of complete Freund's adjuvant, while BTBR mice developed slightly more thermal hyperalgesia. Finally, as measured by the formalin and acetic acid writhing tests, BTBR and Fmr1-KO mice did not show emotional contagion of pain. In sum, our findings indicate that depending on the sensation, pain responses may be mixed, which reflects findings in ASD individuals.

Role of the endocannabinoid system in a mouse model of Fragile X undergoing neuropathic pain

BACKGROUND

Neuropathic pain is a complex condition characterized by sensory, cognitive and affective symptoms that magnify the perception of pain. The underlying pathogenic mechanisms are largely unknown and there is an urgent need for the development of novel medications. The endocannabinoid system modulates pain perception and drugs targeting the cannabinoid receptor type 2 (CB2) devoid of psychoactive side effects could emerge as novel analgesics. An interesting model to evaluate the mechanisms underlying resistance to pain is the fragile X mental retardation protein knockout mouse (Fmr1KO), a model of fragile X syndrome that exhibits nociceptive deficits and fails to develop neuropathic pain.

METHODS

A partial sciatic nerve ligation was performed to wild-type (WT) and Fmr1KO mice having (HzCB2 and Fmr1KO-HzCB2, respectively) or not (WT and Fmr1KO mice) a partial deletion of CB2 to investigate the participation of the endocannabinoid system on the pain-resistant phenotype of Fmr1KO mice.

RESULTS

Nerve injury induced canonical hypersensitivity in WT and HzCB2 mice, whereas this increased pain sensitivity was absent in Fmr1KO mice. Interestingly, Fmr1KO mice partially lacking CB2 lost this protection against neuropathic pain. Similarly, pain-induced depressive-like behaviour was observed in WT, HzCB2 and Fmr1KO-HzCB2 mice, but not in Fmr1KO littermates. Nerve injury evoked different alterations in WT and Fmr1KO mice at spinal and supra-spinal levels that correlated with these nociceptive and emotional alterations.

CONCLUSIONS

This work shows that CB2 is necessary for the protection against neuropathic pain observed in Fmr1KO mice, raising the interest in targeting this receptor for the treatment of neuropathic pain.

SIGNIFICANCE

Neuropathic pain is a complex chronic pain condition and current treatments are limited by the lack of efficacy and the incidence of important side effects. Our findings show that the pain-resistant phenotype of Fmr1KO mice against nociceptive and emotional manifestations triggered by persistent nerve damage requires the participation of the cannabinoid receptor CB2, raising the interest in targeting this receptor for neuropathic pain treatment. Additional multidisciplinary studies more closely related to human pain experience should be conducted to explore the potential use of cannabinoids as adequate analgesic tools.

Brief Report: Associations Between Self-injurious Behaviors and Abdominal Pain Among Individuals with ASD-Associated Disruptive Mutations

Self-injurious behaviors (SIB) are elevated in autism spectrum disorder (ASD) and related genetic disorders, but the genetic and biological mechanisms that contribute to SIB in ASD are poorly understood. This study examined rates and predictors of SIB in 112 individuals with disruptive mutations to ASD-risk genes. Current SIB were reported in 30% of participants and associated with poorer cognitive and adaptive skills. History of severe abdominal pain predicted higher rates of SIB and SIB severity after controlling for age and adaptive behavior; individuals with a history of severe abdominal pain were eight times more likely to exhibit SIB than those with no history. Future research is needed to examine associations between genetic risk, pain, and SIB in this population.

Self-injurious behaviour in movement disorders: systematic review

Self-injurious behaviours (SIBs) are defined as deliberate, repetitive and persistent behaviours that are directed towards the body and lead to physical injury and are not associated with sexual arousal and without suicidal intent. In movement disorders, SIBs are typically associated with tic disorders, most commonly Tourette syndrome, and neurometabolic conditions, such as classic Lesch-Nyhan syndrome. However, beyond these well-known aetiologies, a range of other movement disorder syndromes may also present with SIBs, even though this clinical association remains less well-known. Given the scarcity of comprehensive works on this topic, here we performed a systematic review of the literature to delineate the spectrum of movement disorder aetiologies associated with SIBs. We report distinct aetiologies, which are clustered in five different categorical domains, namely, neurodevelopmental, neurometabolic and neurodegenerative disorders, as well as disorders with characteristic structural brain changes and heterogeneous aetiologies (eg, autoimmune and drug-induced). We also provide insights in the pathophysiology of SIBs in these patients and discuss neurobiological key risk factors, which may facilitate their manifestation. Finally, we provide a list of treatments, including practical measures, such as protective devices, as well as behavioural interventions and pharmacological and neurosurgical therapies.

Risk factors and topographies for self-injurious behaviour in a sample of adults with intellectual developmental disorders

BACKGROUND

Self-injurious behaviour (SIB) is a prevalent form of challenging behaviour in people with intellectual developmental disorders (IDD). Existing research has yielded conflicting findings concerning the major risk factors involved, and in addition, SIB shows multiple topographies and presentations. Although presence of autism spectrum disorders (ASD) and severity of intellectual disability (ID) are known risk factors for SIB, there are no studies comparing SIB topographies by severity degrees of ID and ASD. The purpose of the present paper has been to identify risk factors and topographies for SIB in a representative, stratified and randomised sample of adults with IDD.

METHOD

This study was conducted on the basis of data collected by the POMONA-ESP project, in a sample of 833 adults with IDD. Data concerning demographic and health information, ASD symptoms, psychopathology and ID, have been analysed to determine the presence of risk factors for SIB among participants and to explore the occurrence and topographies of SIB across different severity levels of ID and ASD symptoms.

RESULTS

Self-injurious behaviour prevalence in the sample was 16.2%. Younger age, oral pain, greater severity of ID, presence of dual diagnosis, psychiatric medication intake and higher scores on Childhood Autism Rating Scale were risk factors for SIB among participants, whereas number of areas with functioning limitations, place of residence, diagnosis of epilepsy and sex were not. SIB was more frequent in participants with ASD symptoms regardless of its severity level, and they displayed a higher number of different topographies of SIB. People with profound ID without co-morbid ASD symptoms showed similar results concerning SIB prevalence and topographies.

CONCLUSIONS

Knowledge on risk factors and topographies of SIB might play a vital role in the development of prevention strategies and management of SIB in people with IDD. The mere presence of ASD symptoms, regardless of its severity level, can be a crucial factor to be taken into account in assessing SIB. Accordingly, the presence of SIB in people with ID, especially when presented with a varied number of topographies, might provide guidance on ASD differential diagnosis.

Motor, Somatosensory, Viscerosensory and Metabolic Impairments in a Heterozygous Female Rat Model of Rett Syndrome

Rett Syndrome (RTT), an autism-related disorder caused by mutation of the X-linked Methyl CpG-binding Protein 2 (MECP2) gene, is characterized by severe cognitive and intellectual deficits. While cognitive deficits are well-documented in humans and rodent models, impairments of sensory, motor and metabolic functions also occur but remain poorly understood. To better understand non-cognitive deficits in RTT, we studied female rats heterozygous for Mecp2 mutation (Mecp2^−/x); unlike commonly used male Mecp2^−/y rodent models, this more closely approximates human RTT where males rarely survive. Mecp2^−/x rats showed rapid, progressive decline of motor coordination through six months of age as assessed by rotarod performance, accompanied by deficits in gait and posture. Mecp2^−/x rats were hyper-responsive to noxious pressure and cold, but showed visceral hyposensitivity when tested by colorectal distension. Mecp2^−/x rats ate less, drank more, and had more body fat resulting in increased weight gain. Our findings reveal an array of progressive non-cognitive deficits in this rat model that are likely to contribute to the compromised quality of life that characterizes RTT.

Self-Injury in Autism Spectrum Disorder and Intellectual Disability: Exploring the Role of Reactivity to Pain and Sensory Input

This paper provides information about the prevalence and topography of self-injurious behavior in children and adults with autism spectrum disorder and intellectual disability. Dominant models regarding the etiology of self-injury in this population are reviewed, with a focus on the role of reactivity to pain and sensory input. Neuroimaging studies are presented and suggestions are offered for future research.

What Happened to Paul? Manifestation of Abnormal Pain Response for Individuals With Autism Spectrum Disorder

During the progression of a pilot nutrition intervention designed to teach cooking skills to young adults with autism spectrum disorder (ASD), one participant-Paul-fell in the parking lot. Prior to the accident, Paul had been making significant gains in the program and had communicated in a number of ways his enthusiasm. After his accident, which resulted in broken and dislocated bones in his ankle, his demeanor was dramatically altered, program gains were lost, and staff noted the appearance of many new challenging behaviors. This article analyzes Paul's behavior in reference to the pain response in autism. For some time, it was believed that many individuals with ASD did not experience pain based on anecdotal reports of how individuals responded to injury with seeming indifference. This view has given way of late to a more nuanced understanding of how atypical sensory processing and stimulus over-selectivity spill over into pain pathways and pain amplification mechanisms. The consequence is not a reduction in pain sensation, but a different expression of pain, determined by that individual's particular communicative, cognitive, or physiological challenges. From this perspective, many of the disruptive and harmful behaviors that emerged after Paul's accident can be seen as a delayed response to the incident. This article concludes by arguing that professionals across all domains of health care need to begin to see behavior as communicative for those with ASD. This is particularly true of changes in behavior, which can be significant indicators of health care problems rather than something to be dismissed as another manifestation of the condition.

Pain Assessment and Treatment in Children With Significant Impairment of the Central Nervous System

Pain is a frequent and significant problem for children with impairment of the central nervous system, with the highest frequency and severity occurring in children with the greatest impairment. Despite the significance of the problem, this population remains vulnerable to underrecognition and undertreatment of pain. Barriers to treatment may include uncertainty in identifying pain along with limited experience and fear with the use of medications for pain treatment. Behavioral pain-assessment tools are reviewed in this clinical report, along with other strategies for monitoring pain after an intervention. Sources of pain in this population include acute-onset pain attributable to tissue injury or inflammation resulting in nociceptive pain, with pain then expected to resolve after treatment directed at the source. Other sources can result in chronic intermittent pain that, for many, occurs on a weekly to daily basis, commonly attributed to gastroesophageal reflux, spasticity, and hip subluxation. Most challenging are pain sources attributable to the impaired central nervous system, requiring empirical medication trials directed at causes that cannot be identified by diagnostic tests, such as central neuropathic pain. Interventions reviewed include integrative therapies and medications, such as gabapentinoids, tricyclic antidepressants, α-agonists, and opioids. This clinical report aims to address, with evidence-based guidance, the inherent challenges with the goal to improve comfort throughout life in this vulnerable group of children.

Risk factors associated with challenging behaviour in people with profound intellectual and multiple disabilities

BACKGROUND

Several factors that correlate with the onset or continuation of challenging behaviour are mentioned in research. These are factors related to persons with ID, but also to direct support professionals and the context. Although many of these factors seem to affect the onset or continuation of challenging behaviour in people with ID in general, results are often inconclusive and have little focus on people with profound intellectual and multiple disabilities (PIMD). The present study aimed to assess the extent to which known factors related to challenging behaviour are also applicable to a group of 198 people with PIMD.

METHOD

To determine which factors were associated with challenging behaviour, univariate analyses on associations between known risk factors and challenging behaviour were conducted. The associated factors were then subject to a regression analysis to determine the extent to which they explain the prevalence of challenging behaviour and can thus be seen as factors associated with challenging behaviour.

RESULTS

The results show that, in particular, factors concerning the personal characteristics of people with PIMD, such as sleeping problems and auditory problems, were related to the variance in mean frequency of challenging behaviour. Only one factor related to the direct support professionals was found: when these professionals had been offered training on the subject of challenging behaviour in people with intellectual disabilities in general, they identified significantly more withdrawn behaviour. We found no contextual factors related to challenging behaviour.

CONCLUSION

These findings are generally consistent with findings reported in other studies, especially concerning the personal characteristics of people with PIMD. Further research should focus on the effects of providing safe auditory environments and appropriate sleep schedules for people with PIMD on the occurrence of challenging behaviour.

Deep brain stimulation for severe autism: from pathophysiology to procedure

Autism is a heterogeneous neurodevelopmental disorder characterized by early-onset impairment in social interaction and communication and by repetitive, restricted behaviors and interests. Because the degree of impairment may vary, a spectrum of clinical manifestations exists. Severe autism is characterized by complete lack of language development and potentially life-threatening self-injurious behavior, the latter of which may be refractory to medical therapy and devastating for affected individuals and their caretakers. New treatment strategies are therefore needed. Here, the authors propose deep brain stimulation (DBS) of the basolateral nucleus of the amygdala (BLA) as a therapeutic intervention to treat severe autism. The authors review recent developments in the understanding of the pathophysiology of autism. Specifically, they describe the genetic and environmental alterations that affect neurodevelopment. The authors also highlight the resultant microstructural, macrostructural, and functional abnormalities that emerge during brain development, which create a pattern of dysfunctional neural networks involved in socioemotional processing. They then discuss how these findings implicate the BLA as a key node in the pathophysiology of autism and review a reported case of BLA DBS for treatment of severe autism. Much progress has been made in recent years in understanding the pathophysiology of autism. The BLA represents a logical neurosurgical target for treating severe autism. Further study is needed that considers mechanistic and operative challenges.

Multidisciplinary assessment and treatment of self-injurious behavior in autism spectrum disorder and intellectual disability: integration of psychological and biological theory and approach

The objective of this review is to consider the psychological (largely behavioral) and biological [neurochemical, medical (including genetic), and pharmacological] theories and approaches that contribute to current thinking about the etiology and treatment of self-injurious behavior (SIB) in individuals with autism spectrum disorder and/or intellectual disability. Algorithms for the assessment and treatment of SIB in this context, respectively, from a multidisciplinary, integrative perspective are proposed and challenges and opportunities that exist in clinical and research settings are discussed.

Functional analysis and treatment of problem behavior exhibited by children with fragile X syndrome

The efficacy of function-based interventions for the treatment of severe problem behavior exhibited by individuals with intellectual and developmental disabilities (IDD) is well established. However, few studies have reported on behavioral interventions in fragile X syndrome (FXS) specifically. The present study is a consecutive case-series analysis that reports on functional analysis and treatment of problem behavior of nine children with FXS. Assessment findings were consistent with previous research indicating that among individuals with FXS, problem behavior is more commonly maintained by escape from demands and access to tangible items, relative to the broader population of individuals with IDD. Functional analysis-based behavioral interventions resulted in a mean reduction in problem behavior of 95.2% across the nine participants. Additionally, generalization of treatment effects from controlled clinical settings to home, school, and community was demonstrated. The current findings suggest that function-based behavioral interventions shown to be effective with the broader population of individuals with IDD are also effective for individuals with FXS. Our results in combination with those of previous studies describing functional analysis outcomes provide additional evidence for a unique functional behavioral phenotype for severe problem behavior in individuals with FXS. Implications of study findings for early intervention and prevention of problem behavior in children with FXS are discussed.

New insights into the molecular pathophysiology of fragile X syndrome and therapeutic perspectives from the animal model

Fragile X syndrome is the most common monogenetic form of intellectual disability and is a leading cause of autism. This syndrome is produced by the reduced transcription of the fragile X mental retardation (FMR1) gene, and it is characterized by a range of symptoms heterogeneously expressed in patients such as cognitive impairment, seizure susceptibility, altered pain sensitivity and anxiety. The recent advances in the understanding of the pathophysiological mechanisms involved have opened novel potential therapeutic approaches identified in preclinical rodent models as a necessary preliminary step for the subsequent evaluation in patients. Among those possible therapeutic approaches, the modulation of the metabotropic glutamate receptor signaling or the GABA receptor signaling have focused most of the attention. New findings in the animal models open other possible therapeutic approaches such as the mammalian target of rapamycin signaling pathway or the endocannabinoid system. This review summarizes the emerging data recently obtained in preclinical models of fragile X syndrome supporting these new therapeutic perspectives.

Towards the prevention of behavioural and psychiatric disorders in people with intellectual disabilities

Intervention for behavioural and psychiatric disorders in people with intellectual disabilities often only takes place once these conditions are well established and more resistant to change. As an alternative, this paper promotes a public health prevention model and maps out opportunities for intervention at primary, secondary and tertiary levels. The resulting model is partly derived from generic research into these issues and partly on specific evidence on interventions for people with intellectual disabilities; it also contains more theoretical considerations. The additional research that is necessary to demonstrate the efficacy of the interventions identified is also considered. Central to this proposal is a greater integration of issues for people with intellectual disabilities within much broader policy and research agendas.