Neuropsychology Review

Children with sickle cell disease (SCD) suffer from systemic processes (e.g., chronic anemia, recurrent hypoxic-ischemic events, chronic inflammation) that have been associated with neurocognitive impairment in a range of clinical populations, but which have been largely understudied in relation to specific domains of cognitive functioning in children with SCD. This review focuses on episodic memory, as the hippocampus may be especially vulnerable to the systemic processes associated with SCD. The first part of the paper outlines the pathophysiology of SCD and briefly reviews the extant literature on academic and cognitive functioning in children with SCD, emphasizing the dearth of research on episodic memory. Next, the complex systemic processes of hypoxia and inflammation associated with SCD are reviewed, along with research that has associated these processes with hippocampal damage and memory impairment. The paper concludes with suggestions for future research that are informed, in part, by the literature on developmental amnesia.

Successfully assisting older adults to maintain or improve cognitive function, particularly when they are dealing with neurodegenerative disorders such as Alzheimer’s disease (AD), remains a major challenge. Cognitive training may stimulate neuroplasticity thereby increasing cognitive and brain reserve. Commercial brain training programs are computerized, readily-available, easy-to-administer and adaptive but often lack supportive data and their clinical validation literature has not been previously reviewed. Therefore, in this review, we report the characteristics of commercially available brain training programs, critically assess the number and quality of studies evaluating the empirical evidence of these programs for promoting brain health in healthy older adults, and discuss underlying causal mechanisms. We searched PubMed, Google Scholar and each program’s website for relevant studies reporting the effects of computerized cognitive training on cognitively healthy older adults. The evidence for each program was assessed via the number and quality (PEDro score) of studies, including Randomized Control Trials (RCTs). Programs with clinical studies were subsequently classified as possessing Level I, II or III evidence. Out of 18 identified programs, 7 programs were investigated in 26 studies including follow-ups. Two programs were identified as possessing Level I evidence, three programs demonstrated Level II evidence and an additional two programs demonstrated Level III evidence. Overall, studies showed generally high methodological quality (average PEDro score = 7.05). Although caution must be taken regarding any potential bias due to selective reporting, current evidence supports that at least some commercially available computerized brain training products can assist in promoting healthy brain aging.

Patients with non-central nervous system (CNS) cancer frequently report cognitive complaints, that are recurrent and affect their quality of life. In order to improve supportive care of these cognitive difficulties, it is important to identify associated factors. Sleep disturbance is a good candidate to study, as patients with non-CNS cancer frequently report sleep disorders, and sleep plays a key role in cognitive functioning. The objective of the present systematic review was to summarize the results of studies evaluating the relationship between cognition and sleep in non-CNS cancer, and to highlight the need for further studies. PubMed [Medline] and Scopus databases were screened from April to November 2020 for studies published in English evaluating the association between cognition and sleep in adults with non-CNS cancer. The characteristics and risk of bias for each of the 30 included studies have been reported. Greater cognitive complaints in patients with non-CNS cancer were related to poorer self-reported sleep quality in almost all studies (n = 22/24). By contrast, around half of the studies reported a significant association between poorer neuropsychological performances and sleep complaints (n = 5/11). The studies were found to have several limitations, such as the lack of a control group, which would have shed the light on the period of occurrence of this association (e.g. after cancer diagnosis or after cancer treatments). Our review also identified factors that may influence the relationship between cognition and sleep. Recommendations are given for improving the methodology of future studies and extending the impact of their results.

The verbal/nonverbal account of left and right hemisphere functionality is the prevailing dichotomy describing the cerebral lateralization of function. Yet the fact that the left hemisphere is the superior language processor does not necessarily imply that the right hemisphere is completely lacking linguistic ability. This paper reviews the growing body of research demonstrating that, far from being nonverbal, the right hemisphere has significant language processing strength. From prosodic and paralinguistic aspects of speech production, reception, and interpretation, to prelexical, lexical and postlexical components of visual word recognition; strong involvement of the right hemisphere is implicated. The evidence reviewed challenges the notion that language is solely a function of the “verbal” left hemisphere, indicating that the right cerebral hemisphere makes significant and meaningful contributions to normal language processing as well.

In order that different directions of attention can be organized, they have to be labeled and assessed. A statement of a general problem can be regarded as a label for a general direction of attention. Hope about it, as the perceived probability of sufficient success, on the basis of work done, can be regarded as an assessment. It can be argued that a young infant meets an impasse arising from the work on 2 incompatible general problems, (1) that of raising hope of certainty about the environment (linked to the arousal system because repeated stimulation has less effect), and (2) that of raising hope of producing effects (linked to the activation system because here some effect must be produced before activity can cease). A certainty–right hypothesis, that the right hemisphere deals with the certainty problem and the left deals with the producing-effects problem, and hence keeps work on the two problems apart in early infancy while the corpus callosum is undeveloped, and that a matching specialization continues in later life, is supported.

Researchers have examined if olfaction is a sensitive biomarker of anorexia nervosa, but considerable heterogeneity across studies makes it difficult to reach a consensus. This review and meta-analysis sought to clarify if olfaction is altered in individuals with anorexia nervosa and explore potential moderators of olfaction in this population. We performed quantitative and qualitative analyses of olfactory function in individuals with anorexia nervosa compared with healthy controls. A random effect model was used to estimate pooled effect sizes, and meta-regression was conducted to identify potential moderators. We found that individuals with anorexia nervosa had largely intact olfactory function compared with healthy controls in terms of threshold (g = −0.09, 95% confidence interval [CI] (−0.65,0.47), p = 0.757), identification (g = −0.06, 95% CI (−0.32,0.20), p = 0.642), and overall olfactory function (g = −0.47, 95% CI (−1.02,0.07), p = 0.090). Discrimination was different from control (g = −0.51, 95% CI (−0.97,-0.05), p = 0.029). However, after sensitivity analysis, the pooled effect size was nonsignificant in discrimination. Olfactory sensitivity covaried with anorexia nervosa severity, body mass index (BMI) positively moderated olfactory threshold score (β = 0.79, 95% CI (0.18,1.41), p = 0.020) in individuals with anorexia nervosa. Disease duration negatively moderated olfactory threshold score (β = −0.21, 95% CI (−0.40,-0.03), p = 0.034). The results suggest that olfaction is not a sensitive marker of anorexia nervosa diagnosis, but olfactory sensitivity may be a useful indicator of anorexia nervosa severity.

Stereotype threat is a situational phenomenon, leading to test performance decrements, in which a member of a stigmatized group feels pressured by the possibility of confirming or being judged by a negative stereotype. This review article highlights the progression of research in the stereotype threat field, and its relevance to neurological populations. Early studies focused on demonstrating this effect in African American, women, and elderly populations. Since this time, research has continued to focus on these populations but has moved to elucidating stereotype threat’s mediating psychological factors, studying the impact of individual differences in response to stereotype threat, and attempting to reduce its overall effect. A proposal for further study in neurological populations, under the framework of stereotype threat, comprises the last portion of the paper. It is argued that this social psychological phenomenon may, at least in part, account for poor neuropsychological test performance for neurologically compromised individuals.

Findings on neurocognitive effects of sustained cannabis use are heterogeneous. Previous work has rarely taken time of abstinence into account. In this review, we focus on understanding sustained effects of cannabis, which begin when clinical symptoms of the drug have worn off after at least 14 days. We conducted a search between 2004 and 2015 and found 38 studies with such a prolonged abstinence phase. Study-design quality in terms of evidence-based medicine is similar among studies. Studies found some attention or concentration deficits in cannabis users (CU). There is evidence that chronic CU might experience sustained deficits in memory function. Findings are mixed regarding impairments in inhibition, impulsivity and decision making for CU, but there is a trend towards worse performance. Three out of four studies found evidence that motor function remains impaired even after a time of abstinence, while no impairments in visual spatial functioning can be concluded. Functional imaging demonstrates clear differences in activation patterns between CU and controls especially in hippocampal, prefrontal and cerebellar areas. Structural differences are found in cortical areas, especially the orbitofrontal region and the hippocampus. Twenty studies (57 %) reported data on outcome effects, leading to an overall effect size of r mean = .378 (CI 95 % = [.342; .453]). Heavy use is found to be more consistently associated with effects in diverse domains than early age of onset. Questions of causality―in view of scarce longitudinal studies, especially those targeting co-occurring psychiatric disorders―are discussed.