Advantages of the multiple case series approach to the study of cognitive deficits in autism spectrum disorder

Abstract

In the neuropsychological case series approach, tasks are administered that tap different cognitive domains, and differences within rather than across individuals are the basis for theorising; each individual is effectively their own control. This approach is a mainstay of cognitive neuropsychology, and is particularly suited to the study of populations with heterogeneous deficits. However it has very rarely been applied to the study of cognitive differences in autism spectrum disorder (ASD). Here, we investigate whether this approach can yield information beyond that given by the typical group study method, when applied to an ASD population. Twenty-one high-functioning adult ASD participants and 22 IQ, age, and gender-matched control participants were administered a large battery of neuropsychological tests that would represent a typical neuropsychological assessment for neurological patients in the United Kingdom. The data were analysed using both group and single-case study methods. The group analysis revealed a limited number of deficits, principally on tests with a large executive function component, with no impairment in more routine abilities such as basic attending, language and perception. Single-case study analysis proved more fruitful revealing evidence of considerable variation in abilities both between and within ASD participants. Both sub-normal and supra-normal performance were observed, with the most defining feature of the ASD group being this variability. We conclude that the use of group-level analysis alone in the study of cognitive deficits in ASD risks missing cognitive characteristics that may be vitally important both theoretically and clinically, and even may be misleading because of averaging artifact.

Cognitive profiles of poor readers of Kannada

“…We then proceeded to investigate individual differences using a case series approach. Case series analyses have been used to examine cognitive profiles in cases of atypical development (e.g., Towgood, Meuwese, Gilbert, Turner, & Burgess, 2009;Sprenger-Charolles et al, 2009) and are particularly useful when a complex pattern of deficits within and across different domains is expected.…”

Response Inhibition in Adults with Autism Spectrum Disorder Compared to Attention Deficit/Hyperactivity Disorder

“…Using a case series approach to analysing performance across executive functioning tests also seems a promising new approach (e.g. Towgood et al 2009). …”

“…Previous studies examining executive function in ASD have used similar analysis suggesting that it may be more sensitive to the variation in ability/impairment in neurodevelopmental disorders (e.g. Hill and Bird 2006;Towgood et al 2009). Figure 1 shows the percentage of each group falling below the 5th percentile across measures of RI.…”

Interhemispheric microstructural connectivity in bitemporal lobe epilepsy with hippocampal sclerosis

“…Bearing in mind that in TLE the pathology and severity may vary, this additional analysis allowed better characterization of the level of cognitive impairment of each patient separately on each task (for more details see, Towgood et al, 2009).…”