Journal of the International Neuropsychological Society

The idea of reserve against brain damage stems from the repeated observation that there does not appear to be a direct relationship between the degree of brain pathology or brain damage and the clinical manifestation of that damage. This paper attempts to develop a coherent theoretical account of reserve. One convenient subdivision of reserve models revolves around whether they envision reserve as a passive process, such as in brain reserve or threshold, or see the brain as actively attempting to cope with or compensate for pathology, as in cognitive reserve. Cognitive reserve may be based on more efficient utilization of brain networks or of enhanced ability to recruit alternate brain networks as needed. A distinction is suggested between reserve, the ability to optimize or maximize normal performance, and compensation, an attempt to maximize performance in the face of brain damage by using brain structures or networks not engaged when the brain is not damaged. Epidemiologic and imaging data that help to develop and support the concept of reserve are presented. (JINS, 2002, 8, 448–460.)

This article considers the scientific process whereby new and better clinical tests of executive function might be developed, and what form they might take. We argue that many of the traditional tests of executive function most commonly in use (e.g., the Wisconsin Card Sorting Test; Stroop) are adaptations of procedures that emerged almost coincidentally from conceptual and experimental frameworks far removed from those currently in favour, and that the prolongation of their use has been encouraged by a sustained period of concentration on “construct-driven” experimentation in neuropsychology. This resulted from the special theoretical demands made by the field of executive function, but was not a necessary consequence, and may not even have been a useful one. Whilst useful, these tests may not therefore be optimal for their purpose. We consider as an alternative approach a function-led development programme which in principle could yield tasks better suited to the concerns of the clinician because of the transparency afforded by increased “representativeness” and “generalisability.” We further argue that the requirement of such a programme to represent the interaction between the individual and situational context might also provide useful constraints for purely experimental investigations. We provide an example of such a programme with reference to the Multiple Errands and Six Element tests. (JINS, 2006,12, 194–209.)

Performance on many cognitive and neuropsychological tests may be improved by prior exposure to testing stimuli and procedures. These beneficial practice effects can have a significant impact on test performance when conventional neuropsychological tests are administered at test–retest intervals of weeks, months or years. Many recent investigations have sought to determine changes in cognitive function over periods of minutes or hours (e.g., before and after anesthesia) using computerized tests. However, the effects of practice at such brief test–retest intervals has not been reported. The current study sought to determine the magnitude of practice effects in a group of 113 individuals assessed with an automated cognitive test battery on 4 occasions in 1 day. Practice effects were evident both between and within assessments, and also within individual tests. However, these effects occurred mostly between the 1st and 2nd administration of the test battery, with smaller, nonsignificant improvements observed between the 2nd, 3rd, and 4th administrations. On the basis of these results, methodological and statistical strategies that may aid in the differentiation of practice effects from drug-induced cognitive changes are proposed. (JINS, 2003, 9, 419–428.)

The possible medicinal use of cannabinoids for chronic diseases emphasizes the need to understand the long-term effects of these compounds on the central nervous system. We provide a quantitative synthesis of empirical research pertaining to the non-acute (residual) effects of cannabis on the neurocognitive performance of adult human subjects. Out of 1,014 studies retrieved using a thorough search strategy, only 11 studies met essential a priori inclusion criteria, providing data for a total of 623 cannabis users and 409 non- or minimal users. Neuropsychological results were grouped into 8 ability domains, and effect sizes were calculated by domain for each study individually, and combined for the full set of studies. Using slightly liberalized criteria, an additional four studies were included in a second analysis, bringing the total number of subjects to 1,188 (i.e., 704 cannabis users and 484 non-users). With the exception of both the learning and forgetting domains, effect size confidence intervals for the remaining 6 domains included zero, suggesting a lack of effect. Few studies on the non-acute neurocognitive effects of cannabis meet current research standards; nevertheless, our results indicate that there might be decrements in the ability to learn and remember new information in chronic users, whereas other cognitive abilities are unaffected. However, from a neurocognitive standpoint, the small magnitude of these effect sizes suggests that if cannabis compounds are found to have therapeutic value, they may have an acceptable margin of safety under the more limited conditions of exposure that would likely obtain in a medical setting. (JINS, 2003, 9, 679–689.)

A meta-analysis of 68 studies with a total of 4644 participants was conducted to investigate the sensitivity of tests of verbal fluency to the presence of Parkinson's disease (PD) relative to healthy controls. Both phonemic and semantic fluency were moderately impaired but neither deficit qualified as a differential deficit relative to verbal intelligence or psychomotor speed. However, PD patients were significantly more impaired on semantic relative to phonemic fluency (rs = .37vs..33, respectively), and confrontation naming, a test of semantic memory that imposes only minimal demands upon cognitive speed and effortful retrieval, was associated with a deficit that was of a comparable magnitude to the deficits upon each of these types of fluency. Thus, the disorder appears to be associated with particular problems with semantic memory. Tests that impose heavy demands upon switching may also be disproportionately affected. Demented and non-demented PD patients differ quantitatively but not qualitatively in terms of the relative prominence of deficits on tests of phonemic and semantic fluency. However, patients with dementia of the Alzheimer's type and demented PD patients can be differentiated from one another by the relative magnitude of deficits upon these two measures. (JINS, 2004,10, 608–622.)

This article reports the outcome of a meta-analysis of the relation between the frontal lobes and memory as measured by tests of recognition, cued recall, and free recall. We reviewed experiments in which patients with documented, circumscribed frontal pathology were compared with normal control subjects on these three types of tests. Contrary to conventional wisdom, there is strong evidence that frontal damage disrupts performance on all three types of tests, with the greatest impairment in free recall, and the smallest in recognition.(JINS, 1995, 1, 525–536.)

This study describes psychometric properties of the NIH Toolbox Cognition Battery (NIHTB-CB) Composite Scores in an adult sample. The NIHTB-CB was designed for use in epidemiologic studies and clinical trials for ages 3 to 85. A total of 268 self-described healthy adults were recruited at four university-based sites, using stratified sampling guidelines to target demographic variability for age (20–85 years), gender, education, and ethnicity. The NIHTB-CB contains seven computer-based instruments assessing five cognitive sub-domains: Language, Executive Function, Episodic Memory, Processing Speed, and Working Memory. Participants completed the NIHTB-CB, corresponding gold standard validation measures selected to tap the same cognitive abilities, and sociodemographic questionnaires. Three Composite Scores were derived for both the NIHTB-CB and gold standard batteries: “Crystallized Cognition Composite,” “Fluid Cognition Composite,” and “Total Cognition Composite” scores. NIHTB Composite Scores showed acceptable internal consistency (Cronbach’s alphas=0.84 Crystallized, 0.83 Fluid, 0.77 Total), excellent test–retest reliability (r: 0.86–0.92), strong convergent (r: 0.78–0.90) and discriminant (r: 0.19–0.39) validities versus gold standard composites, and expected age effects (r=0.18 crystallized, r=−0.68 fluid, r=−0.26 total). Significant relationships with self-reported prior school difficulties and current health status, employment, and presence of a disability provided evidence of external validity. The NIH Toolbox Cognition Battery Composite Scores have excellent reliability and validity, suggesting they can be used effectively in epidemiologic and clinical studies. (JINS, 2014, 20, 1–11)