Cognitive reserve and cognitive performance of patients with focal frontal lesions

Sarah E Macpherson,Colm Healy,Michael Allerhand,Barbara Spanò,Carina Tudor-Sfetea,Mark White,Daniela Smirni,Tim Shallice,Edgar Chan,Marco Bozzali,Lisa Cipolotti

doi:10.1016/j.neuropsychologia.2016.12.028

Abstract

The Cognitive reserve (CR) hypothesis was put forward to account for the variability in cognitive performance of patients with similar degrees of brain pathology. Compensatory neural activity within the frontal lobes has often been associated with CR. For the first time we investigated the independent effects of two CR proxies, education and NART IQ, on measures of executive function, fluid intelligence, speed of information processing, verbal short term memory (vSTM), naming, and perception in a sample of 86 patients with focal, unilateral frontal lesions and 142 healthy controls. We fitted multiple linear regression models for each of the cognitive measures and found that only NART IQ predicted executive and naming performance. Neither education nor NART IQ predicted performance on fluid intelligence, processing speed, vSTM or perceptual abilities. Education and NART IQ did not modify the effect of lesion severity on cognitive impairment. We also found that age significantly predicted performance on executive tests and the majority of our other cognitive measures, except vSTM and GNT. Age was the only predictor for fluid intelligence. This latter finding suggests that age plays a role in executive performance over and above the contribution of CR proxies in patients with focal frontal lesions. Overall, our results suggest that the CR proxies do not appear to modify the relationship between cognitive impairment and frontal lesions.

Highlights

It is well known that the cognitive response to brain damage caused by stroke, tumour, trauma, dementia and/or age-related changes can vary across individuals to a considerable degree (e.g., Stern, 2009; Lindenberger et al, 2013)
We retrospectively investigated the effects of years of education and literacy attainment based on National Adult Reading Test (NART) IQ on the cognitive performance of a large sample of patients with focal unilateral frontal lesions
Our unilateral frontal patients were significantly impaired on measures of executive function, fluid intelligence, speed of information processing, verbal short term memory (vSTM) and naming compared to healthy controls

Summary

Introduction

It is well known that the cognitive response to brain damage caused by stroke, tumour, trauma, dementia and/or age-related changes can vary across individuals to a considerable degree (e.g., Stern, 2009; Lindenberger et al, 2013). In patients with similar levels of pathology, high education has been associated with less cognitive impairment than in patients with low education (e.g., Bennett et al, 2003; Ngandu et al., 2007; Roe et al, 2007). Another proxy of CR is literacy attainment, often assessed using the National Adult Reading Test (NART; Nelson and Willison, 1991) or other single word reading tests, as they are assumed to reflect premorbid intelligence (Wiens et al, 1993). Higher NART IQ has been associated with greater CR capacity (Tucker and Stern, 2011; Stern, 2012)

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Results

Conclusion