Language and Cognitive Functions in a Neurological Tumour Population: A Long-Term Follow-Up Study
Complex cognitive capacities such as language and “executive function” are difficult to evaluate in neuropsychological populations due to their multifactorial nature. The current study takes a cognitively-motivated core-skills approach to their assessment. Across four investigations, these various capacities are decomposed into simpler core skills based on current cognitive theory. An undifferentiated sample of 28 neurological tumour patients is then assessed on these skills. In the first study, we assessed the “core skills” underpinning language function at three time points: pre-operative (one day prior to surgery), post-operative (within three days of surgery), and at long-term follow-up (at least three months post-surgery). This approach was sensitive at detecting impairment; indeed, almost half of the patients showed persistent long-term language deficits even at long-term follow-up. The decompositional approach also proved effective at predicting long-term outcomes. Overall, these results suggest that the subtle language deficits may be more common and more persistent than previously estimated in tumour populations. The second study examined the relationship between “core” language skills and sentence-level language processing at long-term follow up. Whilst there were few significant correlations, the results nonetheless suggest that “core skills” measures may be useful predictors of some aspects of sentence-level processing. The third study isolated and identified “core” skills that are essential for complex cognitive control more generally, and assessed these in our patient sample at long-term follow-up. Results were broadly supportive of this decompositional approach, and again, our assessments proved highly sensitive at detecting deficits in this patient sample. The fourth study examined the relationship between language processing and complex cognitive control. Specifically, we examined whether there are systems specially dedicated to the control of language, or whether control functions operate across all domains. Overall, our results were broadly consistent with the domain-specific view - that there may be functionally distinct control systems operating on verbal and nonverbal material. The results, taken together suggest that a core skills approach to neuropsychological assessment has considerable promise, and is worth exploring further in a large patient sample. This approach may also help extend our understanding of the functional organisation of language, and the broader cognitive skills necessary for linguistic operations.