Background: Individuals with fragile-X syndrome exhibit developmental delay, hyperexcitation and social anxiety; they also show lack of attention and hyperactivity. Few studies have investigated whether levels of functioning change with increasing age. Here, we explored developmental changes across adolescence in the cognitive and behavioural…

Background: While behavioural abnormalities are fundamental features of Rett syndrome (RTT), few studies have examined the RTT behavioural phenotype. Most of these reports have focused on autistic features, linked to the early regressive phase of the disorder, and few studies have applied standardised behavioural measures. We used a battery of…

Background: Marshall-Smith syndrome (MSS) is an infrequently described entity characterised by failure to thrive, developmental delay, abnormal bone maturation and a characteristic face. In studying the physical features of a group of patients, we noticed unusual behavioural traits. This urged us to study cognition, behavioural phenotype and…

Background: A growing interest exists in mechanisms involved in behaviour problems in children with mild intellectual disabilities and borderline intelligence (MID/BI). Social problem solving difficulties have been found to be an explanatory mechanism for aggressive behaviour in these children. However, recently a discrepancy was found between…

Background: Previous research has identified that staff-client interactions play an important role in the origin and maintenance of challenging behaviour. Particularly, the reciprocity between staff behaviour and client behaviour has been considered a key issue. Furthermore, severe challenging behaviour has been found to elicit negative emotional…

Background: Children with Autistic Disorder (AD) evidence more co-occurring maladaptive behaviours than their typically developing peers and peers with intellectual disability because of other aetiologies. The present study investigated the prevalence of Clinically Significant maladaptive behaviours during early childhood and identified at-risk…