Asperger syndrome: tests of right hemisphere functioning and interhemispheric communication

Deficient saccadic inhibition in Asperger's disorder and the social-emotional processing disorder

BACKGROUND

Both Asperger's disorder and the social-emotional processing disorder (SEPD), a form of non-verbal learning disability, are associated with executive function deficits. SEPD has been shown to be associated with deficient saccadic inhibition.

OBJECTIVE

To study two executive functions in Asperger's disorder and SEPD, inhibition and task switching, using a single saccadic paradigm.

METHODS

22 control subjects and 27 subjects with developmental social processing disorders-SEPD, Asperger's disorder, or both syndromes-performed random sequences of prosaccades and antisaccades. This design resulted in four trial types, prosaccades and antisaccades, that were either repeated or switched. The design allowed the performance costs of inhibition and task switching to be isolated.

RESULTS

Subjects with both Asperger's disorder and SEPD showed deficient inhibition, as indicated by increased antisaccade errors and a disproportionate increase in latency for antisaccades relative to prosaccades. In contrast, task switching error and latency costs were normal and unrelated to the costs of inhibition.

CONCLUSIONS

This study replicates the finding of deficient saccadic inhibition in SEPD, extends it to Asperger's disorder, and implicates prefrontal cortex dysfunction in these syndromes. The finding of intact task switching shows that executive function deficits in Asperger's disorder and SEPD are selective and suggests that inhibition and task switching are mediated by distinct neural networks.

Coexistent hypothyroidism, psychosis, and severe obsessions in an adolescent: a 10-year follow-up

This is the first longitudinal report on possible psychosis resulting from the juvenile onset of hypothyroidism. A 10-year follow-up in the case of a 13-year-old boy published in this journal in 1993 is presented. The patient presented with a diagnostic dilemma. Although psychosis resulting from hypothyroidism was the most parsimonious explanation of his symptoms (new-onset auditory hallucinations, severe obsessions, and severe hypothyroidism), a primary psychiatric disorder (obsessive-compulsive disorder [OCD] or psychotic depression) aggravated by hypothyroidism could not be excluded. The aim of this study was to illustrate that the diagnosis and clinical interrelationships can be clarified by longitudinal data. FOLLOW-UP DATA: The patient's symptoms responded optimally to a combination of fluvoxamine, risperidone, and levothyroxine (LT4, 300 microg daily). He was free from severe symptoms until age 21, when he discontinued all psychotropic medications while continuing with LT4. Over 2 months later, he was hospitalized for thoughts of hurting himself or others. In the hospital, his LT4 was discontinued and propranolol was started. He was discharged on multiple psychotropic medications, and was rehospitalized 6 days later for suicide risk. When LT4 (200 microg daily) was added to his psychotropic regimen, he partially responded and was discharged. The optimal response to treatment occurred only after he was placed on a combination of fluoxetine, risperidone, and LT4 (300 microg daily). The patient remained stable for up to 12 months of follow-up.

CONCLUSIONS

This chronology suggests that the optimal treatment in this patient probably required three components: a Selective Serotonin Reuptake Inhibitor, (SSRI) risperidone, and LT4 (300 g daily). Each component was apparently necessary but not sufficient individually for the optimal response. The relapse after the discontinuation of fluvoxamine and risperidone (but not LT4) suggests the presence of a primary psychiatric disorder (OCD with depression). The failure to improve without an adequate dosage of LT4 suggests that hypothyroidism was probably an aggravating factor. This case illustrates the diagnostic difficulty in distinguishing between obsessions, depressive ruminations, and delusions in children and the need to consider hypothyroidism in the differential diagnosis of the sudden worsening of OCD, or in cases of new-onset psychosis in children and adolescents.

Asperger syndrome, alexithymia and perception of sleep

Two research traditions, the one on Asperger syndrome (AS) and the other on alexithymia, have produced similar findings independently of each other indicating a possible association between these two phenomena. Both conditions are also associated with impaired initiation and continuity of sleep. Twenty AS adults were compared with 10 healthy controls using the Toronto Alexithymia Scale and the Basic Nordic Sleep Questionnaire. AS subjects were significantly more alexithymic and reported lower sleep quality as compared with controls. AS and alexithymia are associated although the mediating factors are unknown. It is possible that alexithymic traits predispose to anxiety, which in turn lowers the sleep quality in AS adults. Alternatively, low sleep quality might be due to AS itself.