Asperger syndrome and nonverbal learning difficulties in adult males: self- and parent-reported autism, attention and executive problems

A specific overlap between Asperger syndrome (AS) and nonverbal learning difficulties (NLD) has been proposed, based on the observation that, as a group, people with AS tend to have significantly higher verbal IQ (VIQ) than performance IQ (PIQ), one of the core features of NLD. The primary aim was to assess the longer term outcome of NLD—broken down into persistent and transient forms. The present study of 68 individuals was performed in the context of a larger prospective longitudinal study to late adolescence/early adult life of 100 boys with AS. Using self- and parent-report measures, we studied the longer term outcome of the NLD (defined as VIQ > PIQ by 15 points) as regards social communication, repetitive behaviour, attention, and executive function (EF) was studied. Three subgroups were identified: (1) Persistent NLD (P-NLD), (2) Childhood “only” NLD (CO-NLD) and (3) Never NLD (NO-NLD). The P-NLD group had the worst outcome overall. The CO-NLD group had better reported EF scores than the two other AS subgroups. There were no differences between the subgroups regarding social communication, repetitive behaviour, or attentional skills. Low PIQ increased the risk of ADHD symptoms. In the context of AS in males, P-NLD carries a relatively poor outcome, particularly with regard to self-reported EF. However, CO-NLD appears to entail a significantly better outcome. The results underscore the importance of analysing the cognitive profile both at diagnosis and after several years, so as to be able to formulate a realistic prognosis.