The effect of age on cognitive performance of frontal patients

Lisa Cipolotti,Colm Healy,Edgar Chan,Sarah E Macpherson,Mark White,Katherine Woollett,Martha Turner,Gail Robinson,Barbara Spanò,Marco Bozzali,Tim Shallice

doi:10.1016/j.neuropsychologia.2015.06.011

Abstract

Age is known to affect prefrontal brain structure and executive functioning in healthy older adults, patients with neurodegenerative conditions and TBI. Yet, no studies appear to have systematically investigated the effect of age on cognitive performance in patients with focal lesions. We investigated the effect of age on the cognitive performance of a large sample of tumour and stroke patients with focal unilateral, frontal (n=68), or non-frontal lesions (n=45) and healthy controls (n=52). We retrospectively reviewed their cross sectional cognitive and imaging data. In our frontal patients, age significantly predicted the magnitude of their impairment on two executive tests (Raven's Advanced Progressive Matrices, RAPM and the Stroop test) but not on nominal (Graded Naming Test, GNT) or perceptual (Incomplete Letters) task. In our non-frontal patients, age did not predict the magnitude of their impairment on the RAPM and GNT. Furthermore, the exacerbated executive impairment observed in our frontal patients manifested itself from middle age. We found that only age consistently predicted the exacerbated executive impairment. Lesions to specific frontal areas, or an increase in global brain atrophy or white matter abnormalities were not associated with this impairment. Our results are in line with the notion that the frontal cortex plays a critical role in aging to counteract cognitive and neuronal decline. We suggest that the combined effect of aging and frontal lesions impairs the frontal cortical systems by causing its computational power to fall below the threshold needed to complete executive tasks successfully.

Highlights

It is well-recognised that healthy aging is associated with a decline in cognitive processes
Research has shown that self-initiated frontal ‘executive’ processes appear to be the most affected (Craik, 1986) with the greatest anatomical changes found in the Abbreviations: PFC, prefrontal cortex; WMA, white matter abnormalities; TBI, traumatic brain injury; IQ, Intelligence Quotient; CVA, cerebrovascular accident; HC, healthy controls; NART, National Adult Reading Test; RAPM, Raven's Advanced Progressive Matrices; GNT, Graded Naming Test; IL, Incomplete Letters and; CWMA, Composite White Matter Abnormalities n Corresponding author at: National Hospital for Neurology and Neurosurgery, Box 37, Queen Square, London WC1N 3BG, UK
We investigated the effect of age on the cognitive performance of a large sample of patients with focal unilateral frontal or nonfrontal lesion and healthy controls

Summary

Introduction

It is well-recognised that healthy aging is associated with a decline in cognitive processes. Healthy older individuals have reduced cortical volume, increased white matter abnormalities (WMA) and functional over- or under-activation have all been documented in the PFC compared with young individuals (e.g., Cabeza, 2002; Raz et al, 2005; Sullivan and Pfefferbaum, 2006; Fjell et al, 2009; Head et al, 2009) These structural abnormalities are correlated with poorer executive performance (e.g., Nagahama et al, 1997; Gunning-Dixon and Raz, 2003; Van Petten et al, 2004; Raz et al, 2007; Cardenas et al, 2011). Increased WMA and smaller anterior cingulate cortex volume are associated with poorer performance on the Stroop test and fluid intelligence tasks (e.g., Raz et al, 2007; Elderkin-Thompson et al, 2008, but see Salthouse (2011))

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