Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC321
Improvement in neurocognitive function: disassociating habituation from treatment effects
C. J. Marley1, D. Hodson1, J. V. Brugniaux1, K. J. New1, A. Sinnot1, J. Hall2, D. M. Bailey1
1. Department of Sport and Exercise Science, University of Glamorgan, Treforrest, United Kingdom. 2. Department of Anaesthetics and Intensive Care Medicine, Cardiff University, Cardiff, United Kingdom.
Neurocognitive function assessment (NFA) is commonly used to measure neurologic function. It consists of a battery of psychometric tests designed to challenge memory, mental agility and co-ordination and is traditionally used to assess the effect of a vascular surgical intervention (day before and day after surgery) (Newman et al., 2001; Herman et al., 2003) such as carotid endarterectomy (CEA). However, changes typically recorded post CEA, may be misinterpreted as an improvement when they could actually be the result of a learning effect, possibly even coupled with temporary vascular cognitive impairment. Therefore the aim of the present study was twofold; i) to identify the magnitude of improvement in performance between days 1 and 2 ii) to determine whether 4 repeated tests are sufficient to achieve habituation. Twenty healthy volunteers (9♂/11♀) completed a battery of psychometric tests, randomly administered on 4 consecutive days, at a similar time of day. The battery of tests were grouped into 3 subcategories; i) Memory [Ray Auditory Verbal Learning Test (RAVLT), Digit Span Test (RDF + RDB) and the Clock Face Test (CF)]; ii) Mental Agility [Trail Making Tests form A (TMTA) and B (TMTB) and the Digit Symbol Substitution Test (DSST)]; and iii) Visual-motor Coordination [Groove Pegboard Dexterity Test, using dominant (GPD) and non-dominant (GPND) hands]. After confirmation of normality using Shapiro-Wilk W tests, data were analysed using a one-way repeated measures ANOVA and Bonferonni corrected paired samples t-test or the Friedman test and Bonferonni corrected Wilcoxon matched pairs signed ranks tests. Significance was set at P ≤ 0.05. The participants significantly improved in 4/9 tests between days 1 and 2 and continued to improve in all mental agility tests, as well as the RAVLT memory test and GPND visual-motor coordination test throughout the 4 tests (Table 1). These findings are the first to suggest that participants continued to improve their performance in mental agility tests, specific memory and visual-motor coordination tests when performed on 4 consecutive days. Therefore, we may in fact be misinterpreting post CEA data. It is suggested that future research needs to consider alternative (i.e non-habituating) biomarkers of neurocognitive dysfunction.
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